Paul Hamilton

Common, But Strange, Product Design Terms

2011-08-11T10:10:00.001-06:00

Lately I have been pondering over some of the common product design terms we use in our industry. If you really think about some of these terms, you may find like me that in reality they actually make no sense at all. Perhaps they can tell us much about how software vendors have changed our world.

Here are just a few that I think about. There are many others, but I'm going to pick on these three for now.

Top-Down Design

When humans first designed ships that crossed the oceans, do you think they used top-down design or bottom-up design? I really want to know. How did they do it?

I understand what top-down design actually refers to, but does the contrary, bottom-up, ever yield good design? is there really another choice? Is this term simply used due to the nature of our CAD tools we use today? Are we forced to use this term due to some awkward deficiency in our CAD tool? Try to forget about your favorite CAD tool for just a moment. How would you REALLY approach the design?

In-Context Design

What is the contrary to in-context design? Out-of-context design? What is that? Is real product design ever done out of context? No, never has, never will. So why do we need this term? When the rocket scientists designed the rockets that sent men to the moon, did they design them in context or out of context?

Do you suppose they went to the rocket parts bin, and started bolting parts together to make the rocket? I guess that would be an example of out-of-context design (and bottom-up design), and I bet it wouldn’t work. Do we really need special tools and training to keep our designers from designing out-of-context? Again, why does this term exist? Ignore your CAD tool again for a moment. How would you REALLY design a product; in context or out of context? Is there another choice I missed somewhere along my education or career. Does the use of the term have something to do with our CAD tools?

Design Intent

Is there a difference between "design" and "design intent"? I once heard this response from someone after seeing a demonstration of direct modeling: “No, we could never use direct modeling with our products. Our products demand firm design intent”. (Or something close to that). Wow, many thoughts crossed my mind. Thoughts I couldn't repeat in front of them, but will share here: “Are you telling me that your products are so sophisticated that they couldn't be designed without history-based modeling?” Or worse yet: “Are you saying that you can’t design without history-based modeling?” Another crazy thought: “So you think that this rigid design intent will keep you from making mistakes? Oh, right.” Hopefully they are just telling me that it would be more difficult to design their product without it. I’ll think positive and assume the latter.

It’s almost as if humans were never before able to design, and convey the intent of the design, until we had CAD with history trees. History trees certainly provide a useful method of documenting your design "intent". Do they provide the best method of conveying your design "intent"? (And do we really need to use the word "intent" after the word "design"?)

How do you suppose the caveman above was ever able to document and convey the intent that the center hole had to be concentric, at a specific tolerance, to the outer diameter of his new round wheel? Eventually it had to be done. How’d he do it? By the way, how do you REALLY define design intent? What defines it? If your answer has anything to do with CAD - you are wrong. There are certainly many ways to “document” and "convey" your design intent - with history trees, with 3D models, with 2D CAD, even with paper and pencil. What do you suppose is the easiest and most universally understood method of documenting and conveying your design - intent?

Bottom line: Do our tools fit the process of design, or are we forced to adjust the process to fit the tool?

Paul

Some Fun Direct Modeling with Chain and Sprocket

2011-07-25T08:10:00.015-06:00

I hear the term "direct modeling" being used and abuse to describe many different things. To me direct modeling refers to a CAD systems ability to interact with edges, faces, features, parts and assemblies directly during the design process. It means that the CAD system is intelligent, not necessarily the geometry. It means that the CAD system can intelligently interact with geometry regardless of how or where the geometry was created – basically; “what you see is what you get”. There is already a lot of useful information in a solid body. A direct modeling system should be able to recognize this and take advantage of it. Here's an example.

Below is a video I created after doing some direct modeling with some drive chain and a sprocket using Creo Elements/Direct Modeling. As I mentioned in the video I am not sure how useful this is in the real world, but I found it interesting and wanted to share it. I personally have not done much design with drive chain since my brother and I designed and built a go-cart, about a thousand years ago. The chain kept falling off on those tight corners, (and I lost part of my eyebrow on another tight corner. "Wear a helmet, stupid" - Whatever!).

Chain is interesting simply due to the relationship from one link to the other. By recognizing the physical properties of the solid bodies that make up the chain, you can visualize some of these interesting behaviors, especially as it interacts with the sprocket.

For this example I started out by downloading the sprocket and chain in STEP format from a 3D content web site. I then created the simple shaft in the center of the sprocket. All parts are dumb solids, and there are no assembly relationships to begin with. In the “Position” function of Modeling there is an option called “Physical”. If you turn this option on, the system will recognize the physical properties of the 3D solid models, and recognize the relationships between models in real time (or very close to it). You will notice that I do eventually put a fixed relationship onto the shaft, but I apply no other relationships to the models or assembly. There are no “user defined” relationships defined between the chain and the sprocket, and there are no assembly references. What you see is what you get. Watch:

What I find interesting is the various ways of using the “Relations” capability together with the “Physical” option when moving parts. The system doesn't recognize gravity, acceleration or anything like that so it’s not doing kinematics. It simply knows moments of inertia, CG and the fact that these models are solid. And best of all – it makes no difference how the models were created or assembled, and on what CAD system they were created or assembled, (just had to throw that in).

Paul

Direct Modeling and Variant Design

2011-07-18T08:05:00.000-06:00

Designing products with the help of a CAD tool that is history-based (some call it parametric modeling) has been the norm for many years now. However there are thousands of companies around the world that have been successfully designing products with CAD tools that do not retain modeling history. We call this technology direct modeling. It’s more than just modeling however. Depending our your product characteristics and processes, the flexibility that comes with direct modeling may provide a better environment and methodology for supporting your particular design environment. This direct modeling methodology is catching on and now spreading rapidly.

The technology behind this methodology is experiencing substantial improvement. With some of the CAD systems out there that are based on this technology it is now possible to parametrically control models and assemblies – without recording modeling history in an ordered way. The term “parametric modeling” can no longer be used to describe history-based modeling. Parametric modeling can be done with or without history.

The benefits include the fact that with the direct modeling methodology there is no need to plan ahead. Users can create and manipulate geometry anyway possible. Relations and constraints (design intent) can be added on the fly as need. There is no need for strict and consistent modeling practices. It simply makes no difference how you come up with the geometry. And it can work on any geometry; 2D, 3D wires, surfaces, and solids, regardless of where it comes from or how it was created. With direct modeling, geometry is the master, rather than the proprietary history tree.

In the past there were several areas where history-based modeling and the ordered model provided many advantages over history-free direct modeling. One of those areas was in regards to the development and management of family , or variant parts. The ordered structure made it relatively simple to represent a part in several slightly different states or configurations. With adherence to modeling standards and careful development of the 3D history-based model, the model can be “programmed” to support the family variants simply by changing a parameter.

Below is a video of doing something similar with history-free direct modeling using the PTC Creo product “Creo Elements/Direct Modeling” (“CoCreate” or “SolidDesigner” for the old guys like me.)

In this case I am starting with an IGES file just to highlight the fact that with the direct modeling methodology, it makes no difference where or how the geometry came into existence, or if proper methods were used in creating it. Perhaps this is an example of a model coming from a supplier that uses a different CAD tool. In this scenario we need to add some design intent to the model so that we can represent other variants that may be required of this part. With traditional history-based modeling this would require a model rebuild.

Perhaps in another video I can show you how the assembly configuration can actually be used to drive the configuration of this part.

Imagine a design process that does not involve planning ahead, ordered models, model rebuilds, strict modeling practices, proprietary data, regeneration failures and the mind-numbing web of relationships and references. Well, it’s not too far away.

Paul

Is Your Investment in the Structured Model Generating a Positive Return?

2011-06-21T15:15:00.005-06:00

As I've mentioned before, in my current job I get to visit and interact with many people and companies involved with product development; several every week. Most of these people/companies use history-based modeling of some kind as their primary design tool. As I walk through their processes and tool usage,I am continually amazed at how little value most companies get from their history based design tool and the resulting structured model, considering the level of investment that goes into the development and manipulation of the structured model. It seems that rarely is the potential value of the structured model realized. I say this based on a few observations:

I've had the opportunity to look at many history based models/assemblies and review their history trees and structure, coming from a variety of different CAD tools. While I see some models that are well structured with a good representation of design intent, most models are very poorly structured and really make no sense. They are clear examples of people just trying to get their job done as quickly as possible; get the models built, evaluate the design, make drawings and make parts. And a lot of these models are coming from companies that I would consider high tech and leaders in the industry.
For further review I often load these models into my CAD tool of choice (Creo Elements Direct Modeling) and run a simple interference check. Since they are structured models I assume that errors will not exist, as many people believe that the structured model keeps them from making errors. Unfortunately, and all too often, I find many errors.
I also find that recreating models is not too uncommon. This doesn't indicate that they are not getting value from the models, it just indicates that the cost of a well structured model may be much higher than most realize.

Why are we investing so much time, effort and money into history-based modeling and the structured model, when so often we are not getting the value from it that we could/should? Here are the most common answers I hear, or can assume based on what I see, with #1 being the most frequent.

They don't know of, or recognize, any alternative. Many people truly don't know that there is an alternative to history-based modeling and the structured model. Value is a relative thing, and if there is no recognition of alternatives, there is no recognition of opportunity.
Many companies assume that strict modeling practices are being followed and as such assume they are getting value from it, but have really not done any work to validate this.
The company may not be open to an alternative as migration costs are assumed higher than the potential return. Of course understanding potential return will require a clear understanding of alternative solutions.
Individuals may not be open to an alternative as they have bettered their career based on their knowledge and skill with a particular tool. Learning a new one will set them back.
User preference often gets higher priority than process improvement when it comes to tool selection. The cost of training can contribute to this. A lack of understanding in how the tool impacts process also contributes to this.
Others?

Of course the alternative I am referring to is direct modeling and the unstructured model. Most all CAD companies are working on this technology and are presenting it in some form or another. This alternative is becoming much more prevalent in our industry.

Before you start jumping to conclusions about the lack of value in an unstructured model, be careful not to assume that the unstructured model cannot be predictably controlled and/or represent design intent. Creo Elements Direct Modeling, for example, has a powerful 3D parametric solver built into it. Users can add control and design intent to geometry and assemblies at anytime in the process, independent of where or how the geometry was created. An IGES file can even be parametrically controlled and easily be made intelligent if desired. Assemblies and mechanisms can easily be brought to life for virtual prototyping. And don't confuse design intent with modeling intent. Here's an old example using imported models (although I should update this to Creo):

So the question is, are you really getting value from your investment in history-based CAD tool and the structured model? If so, what value? Do you understand the total investment, and does the value justify the investment? Are you sure you understand the alternatives?

There is certainly value that can come from the structured model, but many times this value comes at a great cost. I could go on about the various perceived values that people think they are getting from the structured model. Some are valid, some are not. Perhaps that is a topic for a different post.

Paul

Creo, My Take on It - Part 3

2011-04-05T08:00:00.001-06:00

Part 3: Creo and “AnyRole Apps”

<<Part 2

One of the things you will hear PTC talk about in the context of Creo is AnyRole Apps. Creo is a scalable suit of right-sized, purpose-built, interoperable apps built on the common data model. It is all about providing the most appropriate and right-sized application for the task at hand. There, that’s the marketing stuff.

So, what value does the concept of AnyRole Apps bring to product development organizations and their development processes? The way I see it is that while AnyMode Modeling allows for creating engineering data in a variety of ways while maintaining consistency in the data model, AnyRole Apps is about allowing others to more easily consume, utilize and add to the engineering master.

Before Creo there were two choices for any potential contributor or consumer of engineering data:

Equip these people with the common heavy CAD tool that is used for core product development, including training and best practices. In many cases this tool was far more powerful and complex than what was actually required, depending on use cases.
Or – allow these people to use the most appropriate tool of choice with a high probability of disconnecting the downstream deliverables from the engineering master, resulting in potential interoperability issues and duplication of effort.

With PTC’s concepts around AnyRole Apps, the engineering master is maintained regardless of roles and the supporting applications that may be used. This concept certainly can be of high value to companies that have chosen the history tree and the resulting ordered model as the engineering master. It can also be of value to companies that have chosen direct modeling and geometry as the engineering master.

With the Creo apps, for example, you no longer need a full CAD tool just to render an image that is associated to the master data - or interrupt a busy CAD expert to have them generate the image for you. The Technical Publications department may no longer need to maintain a full CAD tool just to develop associated animations for the Service department.

My Understanding of Potential Creo Applications

Certainly a significant feature of the PTC Creo applications is that they will all have the same look and feel from a user experience point of view. They will also have the same look and feel from an IT perspective. But what I think really makes Creo unique is the potential to maintain the connection to the ordered model regardless of the app being used and the person using it. Higher individual and process productivity, improved interoperability, and reduced duplication of effort are all possible benefits.

My conclusion:

I’ve seen the slides from PTC that show the 4 big problems they claim to solve with Creo. If in fact they did is a decision you will have to make for yourself. For me it comes down to this. Use the tool that best fits your needs and enables you to be most productive - no need to be burdened with functionality that you will never use. Enable others, besides the CAD experts, to participate in the product development process with controlled contribution and interaction to the engineering master. Eliminate disconnects with the engineering master, and reduce the duplication of effort. Could it be that simple? Well, since Creo is not yet released, I guess we'll have to wait and see.

There is certainly much more to Creo than what I have covered here, but I hope it has given my readers a little better idea of what Creo is about - from my perspective anyway. Hope to give you a demo soon.

Paul

Creo, My Take on It - Part 2

2011-03-29T11:20:00.005-06:00

Part 2: Creo and “AnyMode Modeling”

<< Part 1

There is a significant difference between using a parametric (history-based) system as your primary design tool and using a direct modeling (history-free) system as your primary design tool. These two technologies offer completely different methodologies and experiences for product development. Certainly a company that has standardized on parametric modeling may get value from the flexibility of direct editing in certain areas of the process, but if they have chosen the history-tree to be the engineering master (document of record), the history-tree needs to remain the master. If, on the other hand, a company chooses direct modeling as their primary design tool and understands geometry to be the engineering master, geometry needs to remain the master.

With Creo, I don't think PTC is somehow attempting to mix these two in some convoluted way, inevitably leading to a compromise in both methods and data. On the contrary, PTC is providing powerful purpose built solutions, tied together through the common data model.

For the company that has chosen to standardize on a parametric history-based solution, Creo provides a high-end purpose-built no compromise parametric modeling app AND a complimentary purpose built direct modeling app. This particular direct modeling app provides an option to track direct edits into the common data model. These records can then be accessed and consumed by a parametric app that can make sense of them as it relates to the ordered feature tree. The user of the parametric app is given a choice to accept or reject modifications. If accepted, the edits will be reflected appropriately in the tree. This direct app can be used in a parametric environment to allow infrequent users, or perhaps even non-CAD users of the parametric app to more easily participate in the design process. This capability makes it possible to take a fully parametric model into a much simpler direct environment, make edits as necessary, then bring it back into the parametric environment with NO data loss – maintaining the engineering master. I’ve heard some call it “round tripping” (P>D>P: Parametric>Direct>Parametric). PTC’s round trip is made possible via the common data model and is very unique. It is of course important to understand process to determine where this type of workflow makes sense, but when and where it does, Creo can support it.

With Creo, PTC is also providing the best most powerful direct modeling app on the market that is capable of supporting complete art-to-part. For companies that chose direct modeling as their primary design tool, and geometry as their master, Creo provides the best, no compromise solution. This app comes with a synchronous parametric solver when firm design intent is needed. These customers can also take advantage of the parametric app as needed if and when there are circumstances that are well served with the parent/child relationship of parametric modeling. Via the CDM, the resulting geometry can quickly and easily be incorporated into the direct design environment and carried forward as native data.

Part 3

Paul

Creo, My Take on It - Part 1

2011-03-23T08:00:00.003-06:00

I have written about Fusion, SpaceClaim and recently Synchronous Technology, so I guess I should write something about Creo. I am an employee of PTC so I want to make it clear that what I write on my blog is my own personal opinions and may not reflect the opinions of my employer. At PTC I am responsible for technical sales. I am not a product developer, product manager or in a marketing position, so I have no direct responsibility for what Creo is. I view the development of Creo from the sidelines (although I guess that’s better than the bleachers).

I’m sure that most of you have already heard about Creo. I’ve read much about it online in many publications, blogs and forums. There seems to be many different ideas about what it is, what it’s going to be, and what it is not. It’s been interesting to see what PTC is working on and seeing it come to reality. PTC already has the most robust direct modeling technology in the CoCreate product, now Creo Elements/Direct. And of course, they also have the most powerful parametric modeling tool in Pro/E, now Creo Elements/Pro. As a matter of fact these products were the first of their kind that led to many followers – in both cases.

Part 1: Creo and the “Common Data Model”

So what is Creo? The graphic above is indicating the concept of many purpose built applications, all with a common user interface and a common user experience. These apps are sitting on top of what PTC is calling the “common data model” (CDM). There are many advances PTC is making with Creo. For me I am always interested in what’s happening on the direct modeling side, and Creo certainly involves direct modeling. But before getting into that it may be more appropriate to discuss this common data model, (CDM), as this sets the stage for much of what Creo is.

In the graphic above the blue internal arrows basically reference the common data model. I overheard a PTC Product Manager describing the CDM as a book with chapters. It sounded like each chapter could contain different things related to the data that may be created and consumed in the context of Creo. Depending on the “app”, different chapters may be accessed for storage and retrieval. Beyond this I don’t know a lot of details, but I could envision how there could be a chapter for 2D geometry, one for 3D geometry, one for design intent, one for the associated drawing, one for FEA attributes, one for sheet metal attributes, one for NC tool paths, one for technical pubs, and so on. And it’s conceivable that multiple apps could be accessing the CDM synchronously, interacting with the appropriate chapters as needed. The CDM is much more than a common file format or a common data structure and the possibilities are intriguing.

If I’m correct, or at least close in my description of the CDM then the concept of what PTC refers to as “AnyApps”, can really start to make sense. This could be a very powerful approach in solving many issues related to interoperability and consistency across purpose built apps. Lightweight purpose built apps that can read and write into the different “chapters” of the CDM as needed. This would be true of all the “apps”, even the bigger geometry creating apps, whether direct or parametric. Through the CDM a person could chose to use a purpose built standalone 2D app to do some early concepting, for example, and never be disconnected from the engineering master. In this example, the 2D geometry could then easily be utilized in the development of a 3D model, while the CDM maintains the appropriate linkages and consistencies. Today the only way to get this level of consistency is with one big monolithic application that does it all.

Time will tell, and as I learn more about it I hope to share it with you. It seems that the CDM puts the right foundation to Creo.

Part 2

Paul

Direct Modeling Continues to Catch On

2011-02-08T13:30:00.005-07:00

It should be no surprise that interest in direct modeling is continuing to grow, and at an ever increasing rate. Every major CAD vendor now has a strategy around direct modeling. These companies don’t do this because of some fascination with technology. Most are public companies and must show growth, revenue and profit. They do it based on real business potential.

This growth, however, has nothing to do with direct modeling somehow being better or more functional than traditional history-based modeling. These two methodologies are very different and they add value to the product design process in many different ways and in many different areas. There is no need to debate which is better. That is a pointless debate. The market has now proven a strong need for both methods.

I can name many companies that are currently standardized on history-based modeling for their product development, but are now adding direct modeling to their environment to improve specific areas of the product development process. These companies are not adding direct modeling due to some missing functionality in their history-based tool. As a matter of fact, some of the direct modeling tools they are deploying are much less functional than their standard CAD tool. Another important fact is that their addition of direct modeling is not causing a reduction in the seat count of their standard tool. Why do you suppose this is happening? Why would a company that already owns the most capable CAD tool on the planet (whatever you think that is), add direct modeling to their toolset - without reducing the seat count of their standard CAD tool? They already own a very capable CAD tool and yet they are realizing value from direct modeling. Do you have any idea why this is happening? In my little world I see it happening every week. If you don’t know, you certainly should.

There are also thousands of companies around the globe that have standardized on direct modeling as their primary CAD tool of choice for product design, from concept to manufacturing. This choice is based on their product characteristics and product development process. I can assure you that this choice was not some uninformed, unintelligent choice made in a vacuum, or perhaps made by some highly opinionated user. Most all of these companies switched from traditional parametric history-based modeling and continue to reap huge benefits from the switch, again, based on product and process characteristics. This wholesale switch however makes up a very small percentage of the growth that is happening in direct modeling.

It’s obvious that in most cases where direct modeling is being deployed, the hardcore full time CAD users are not switching to direct modeling. Many are satisfied and productive. So where does the value come from to justify the addition of direct modeling? I can give you many real-world use cases, but I’ll let you consider it yourself for a while, or you can read this, it’s my: Top Ten Reasons Companies add Direct Modeling to their Product Design Toolbox”

Most people I meet in my business are very involved in product development and many are serious CAD users, and yet most have never heard of direct modeling and have no clue what it is. I guess this would indicate that the growth we are seeing in direct modeling is only the tip of the iceberg … uh, maybe that’s not a good analogy... :<)

Paul

Product Design in 2011

2011-01-26T08:35:00.001-07:00

Wow! We are already well into 2011 and I haven’t posted to this blog since October. Happy New Year everyone! (Kind of late with that)

Maybe I am imagining things, but it seems to me that in 2011 we are going to see some significant differences in the tools we use to support product design. Are you keeping up with all the craziness going on out there in CAD and PLM? Well you sure should be. Consider the recent news about SolidWorks and Dassault, PTC Creo, new releases of Synchronous Technology, Spaceclaim and much more. It’s going to be an exciting year for sure.

2011 is going to be an exciting year for me as well as I am very much involved with Creo at PTC. For the previous two years I have been responsible for technical sales of the CoCreate products. Since October I am now responsible for technical sales of Creo. It’s much bigger and broader, and there is huge interest out there. As such, since October my work life has been a bit crazy and the workload continues to grow. It’s enjoyable and exciting to see and hear the responses from people once they understand what this Creo thing is. I have a post I’ve been working on for some time now regarding my take on what Creo is. I hope to post it soon – we’ll see.

As you probably know from this blog, I’m somewhat of a direct modeling guy. It is interesting to see that the concept of direct modeling is making its way into the portfolio of almost every CAD supplier. Do you realize now that almost every CAD tool out there that is based on direct modeling (Synchronous Tech, Elements/Direct (CoCreate), SpaceClaim, KeyCreator) now has the ability at some level to capture design intent on history-free models? That you can control this so called “dumb solid” parametrically? Of course some do it better than others and it’s still somewhat more robust in history-based CAD, but in a few years it will be nothing special. Watch what happens in this area in 2011. With direct modeling, this type of history-free control and design intent is not dependant on the modeling process and can be applied to any geometry from any source. You will no longer have to confuse “Design intent” with “Modeling Intent” ;<).

What kind of things may happen in the CAD world for 2011? There’s certainly a good amount of talk about CAD in the cloud. What is that, anyway? Seems every time I talk about it with someone I hear a different perception about what it is and what value it brings. Not sure I can answer those questions yet. Maybe it will be something like the on-line computer games our kids are playing, (ok, I do too – whatever). There is some fascinating technology in that space that we could be taking advantage of. Someday soon you may be interacting with PLM technology, and not know it -- “Inconceivable!”

I think it is safe to say that the pace of change in our world of product design is not slowing down. It would be fun to hear from some of you. What do you see coming this year?

Will Solidworks -on the CATIA kernel -on the cloud -on … whatever else, change our world in 2011?

What about PTCs Common Data Model? Will it change the way we interact with each other? I can tell you it has never been done before.

Will we figure out how to reliably reconcile a history tree based on external geometry edits?

What about the proprietary history tree? Will it continue to be the preferred engineering document of record?

Are we going to see history-based modeling magically merge with history-free modeling into some sort of CAD antimatter?

Will touch screen CAD finally catch on? (But what if it’s in the cloud?)

Will we somehow learn when to use ordered features versus unordered features?

Just how many new releases of SpaceClaim can they squeeze into 2011? They’re off to a good start.

Will our CAD UI make a giant leap in becoming less significant?

Last but not least: Will Jon Banquer finally get the CAD/CAM tool he’s been long searching for? Oh please! Oh please! (just for you Jon :<)

Paul

Solid Edge ST3, My First Impressions (part 2)

2010-10-18T09:00:00.002-06:00

In Part 1 I described my observations regarding how Solid Edge ST3 lines up with some of the typical issues related to traditional parametric history-based modeling. In this Part 2 I will share some of the other crazy observations I have:

Here is a statement coming from synchronoustechnology.net: “You no longer have to choose which modelling workflow to use up front, instead it is a simple case of switching between ordered (traditional) and synchronous whenever required.” And, by the way, if you “switch”, or move an ordered feature to Synchronous, there is no going back. It’s a one way trip. Siemens still provides no ability to rationalize the history-tree (ordered) from a direct model/feature (synchronous). Something that Autodesk is struggling to solve with their Change Manager. With SE ST3 it seems real simple to move ordered features to synchronous. Since it is a one-way trip, I wonder how long it will take before all your Solid Edge history-based (ordered) data is completely history-free (synchronous/unordered).

When reading about SE ST3 I started having flashbacks to the mid 90’s. This started sounding strangely familiar. At the time I was fairly close to the developers of TriSpectives at 3D/Eye, now known as IronCAD, (CAXA in China). Here is a good article with some of the IronCAD history. IronCAD has always been and is still a parametric history-based system at its core. Although it was only a few years ago that they exposed the history tree structure to the user. Due to the systems ability to automatically reorder the tree structure, it was infrequent that a user actually needed to manipulate the structure manually. IronCAD did several things different from traditional history-based modeling systems. I had included much more detail on IronCAD while writing this but as I was writing Deelip Menezes published an extensive review of IronCAD. So I will refer you to his review for more detail on the similarities of IronCAD and SE ST3. In summary there are many similarities, although IRONCAD has been providing this type of "mixed mode" capability for many years now.

It seems to me that the synchronous features in the ST3 tree simply represent a single B-Rep model organized somewhere in the tree. You might consider it what other parametric history-based systems refer to as the “base feature”, although with ST3 this B-Rep is ordered somewhere in the tree, and can contain UDF’s (user defined features). In ST3 these UDF’s are actually defined by a modeling operation. When you drag and drop a feature from ordered into synchronous, you are simply taking the geometrical results of an ordered feature and adding that geometry to this single B-Rep, and then removing the ordered feature definition. This single B-Rep becomes more complex, or detailed, with each addition. The resulting new faces in the B-Rep are tagged to keep them grouped as a UDF. Am I over simplifying this?

I am not saying that any of this is bad. On the contrary I like to see this kind of stuff pushing all of us in our thinking of CAD. But as you are considering this, just keep in mind what our ultimate objective really is; and that is - designing products (sometimes 3D models can help us do that).

Paul

Solid Edge ST3, My First Impressions (part 1)

2010-10-18T08:00:00.006-06:00

It looks like Solid Edge is getting a lot of new functionality and modeling capability. I am not a user of Solid Edge and as such my “first impressions” have nothing to do with the new functionality. I will leave that up to the users and experts. What I am most interested in is what they have done with Synchronous Technology and the Solid Edge model structure.

When reviewing technology I try to see things from a process and workflow point of view. As you probably already know I am kind of partial to direct modeling. I certainly understand the value of the parent/child relationship that comes with the history tree, and the associativity that it can provide, but I see all too often that many designers are over-served with this technology. The challenges that come with history-based modeling sometimes overshadow the benefit. These challenges have driven and accelerated the development of direct modeling. The challenges I speak of include the following:

Complexity of the tool and general training requirements
The need to plan ahead before modeling
Interoperability and data exchange
Reusing history-trees (history-based models)
Resolving conflicts in the history-tree
The need for modeling standards and best practices

Again, I understand the benefits, but all of the above can keep you from getting your job done in a timely manner. And it is these issues that are driving the interest in direct modeling. There are still some yet unsolved challenges with direct modeling of course, but none of the above apply with mature robust direct modeling.

So my question is: How does Solid Edge ST3 impact the issues listed above? Is life improving for the typical Solid Edge user? Let’s take them one at a time.

Complexity of the tool and general training requirements: In my opinion SE just became harder to learn. Even if you will never use Synchronous, or will never use Ordered, just having those buttons on the menu just made it more complicated. It is safe to assume that the training manuals just got thicker. It looks intuitive enough, but it goes deeper than that. How, when, why is it acceptable for a user to move a feature from Ordered to Synchronous?
The need to plan ahead before modeling: It doesn’t matter if you are in a history-free mode (synchronous, direct, unordered, whatever) or in a history-based mode (ordered, parametric, whatever), if the system is recording information about the modeling process (modeling features) you will need to plan ahead and model carefully, if you intend to realize any future value from the record. In synchronous mode, the order may have no relevance to the future use of the model, but the collection of faces recorded in the feature certainly will. Will SE ST3 be a good concept design tool? The chaos of concept design often times renders a history tree completely unorganized and useless. Very often this will lead to a model rebuild when moving to detail design. Does SE ST3 resolve this?
Interoperability and data exchange: We all know that history-trees are proprietary and that exchanging history-trees between different history-based systems is flaky at best. Geometry is common between all CAD systems, and with robust direct modeling we can make use of any geometry and edit it freely. My only problem with SE ST3 in this area is that I see no evidence that they have improved the robustness to handle the demands of complex direct modeling. I’ve had a few chances to try Synchronous Technology in NX and SE in the last year, but was never really impressed with its ability to resolve complex topology changes on imported models. Live rules or not, the system needs to be able to handle the demands of direct modeling. Like I said “I see no evidence” of improvement in this area so I can easily be proven wrong on this one. I just need to see it to believe it.
Reusing history-trees: It has always been a bit of an issue when reusing a history-based model that you created many months/years ago or that someone else created. You need to spend some time studying the tree structure before you can really make use of it. It seems that with ST3 the tree structure just got more complicated. I know, you don’t have to use both modes in one model, but can you control the other users?
Resolving conflicts in the history-tree: I guess if you do have a conflicted or corrupt history tree, with ST3 you can just take all those features and move them to Synchronous. That would fix it, right? What about all the other references and relationships tied between those ordered features and their children and/or other parts/features? How are those resolved in ST3?
The need for modeling standards and best practices: I have seen some fairly thick 3-ring binders full of documentation on modeling best practices. These are usually created by larger organizations to train users and ensure that these users are creating history-trees that have some consistency in them in order to better ensure these models (history-trees) can be used in the future and by others. I think with ST3 these binders just got bigger. I can see some more best practices coming.

Solid Edge has certainly come a long way. The SE ST3 videos they have online look fantastic (as they should). I do commend the product managers and developers of Solid Edge for pushing the envelope on this. They have introduced some interesting concepts with ST3. I’m anxious to see how it continues to develop. I am still not convinced that they have the “best of both worlds”, as some fellow bloggers have already indicated. Sorry, I am just a bit skeptical. I hope it doesn’t turn out to be one of these:

Paul

Part 2

Considering the Cost vs. Benefit of CAD

2010-09-14T07:00:00.006-06:00

As a manager or leader of product development, have you ever wondered what the real value is of all that CAD data that is being created? Are you getting a positive return on your CAD investment? Probably a strange question to ask since everyone seems to concur that CAD is one of the basic necessities of product development. I’m actually not questioning if CAD is adding value, what I’m questioning is just how much of CAD is adding value. Our CAD tools are incredibly powerful – whether you need it or not.

When I first started my career I worked as a machinist in a prototype and model shop at Hewlett Packard. One of my specialties was in designing and building soft tools (molds) for plastic parts. At that time most of the product designers and engineers were well on their way of moving from 2D CAD to 3D CAD. I could easily tell a difference in the drawings as they moved to 3D CAD. With 2D CAD I would get drawings with a single line that represented the side of a part or feature, with a note designating plus draft or minus draft – very easy to deal with in 2D CAM. With 3D CAD I started getting drawings with two lines representing the side – with no notes. At that point in time, the cost of the drafted 3D model was actually higher than the value – cost being related to the effort to create the draft features AND to use them. We actually stopped putting draft on models for a while. Of course as both CAD and CAM improved, and our use of the 3D model improved, the value of the drafted model soon surpassed the cost.

That’s a long story to make a simple point. Are you getting a positive return on your CAD efforts and resulting data? I have no question that you are getting positive value from a complete and accurate 3D model (even though in some situations we are still removing features that someone spent time creating). My question is more related to all the other stuff we are doing with CAD. Is it adding value beyond effort? We have some amazingly powerful capabilities in our modern day CAD tools. Being a guy that really enjoys CAD, I want to master and use them all, whether I need to or not.

I find it fascinating to see how much time a CAD jockey can waste on coming up with some elaborate associative parametric solution to a problem that really didn’t need to be solved in such a way. It can certainly be challenging and at times enjoyable, kind of like solving a Rubix Cube. Of course there are many times when this capability yields very high value, and that is why this power exists in the first place. But is it required in the design of all of your parts/products? What about simply getting parts out the door? Sometimes I think we get sidetracked from our real objective; and that is to design products, not model them. Just to be clear, I am not trying to make a case for or against history-based or history-free modeling. In CoCreate (the product I represent) I can fully parametrically control models and assemblies, in some very elaborate and intriguing ways. “Over modeling” can be done in most any CAD tool. (That’s my new term for the day: “over modeling”.)

It would be interesting to evaluate the effort that goes into all of the additional intelligence and associativity that we are building into our models versus the actual value that we are getting from it. Often times this intelligence is considered insurance against mistakes, although it is not too uncommon to apply this intelligence incorrectly. There are other, and sometimes cheaper, ways to ensure correctness. Perhaps we consider this extra layer of intelligence to be necessary to convey design intent to other team members and downstream functions. This is certainly valid in many situations, but there are less costly and simpler ways to convey design intent. Sometimes we are adding this extra layer of intelligence to the model simply because the CAD tool forces us to; it’s intrinsic to the modeling process.

What about the life-cycle of this intellectual property we call "model intelligence"? Will it be easy to “consume” and extract value from throughout the life-cycle of the resulting product? Can it be leveraged in other products we are designing? Is it built on standards or specific to a particular tool? What is the possible value? Does it yield a positive return?

Often times the problem is simply that we may not realize that there is an alternative to what we are doing. Have you considered the alternatives? If you do not recognize alternatives, you will never recognize opportunity.

Paul

Top Ten Reasons Companies add Direct Modeling to their Product Design Toolbox

2010-08-30T08:10:00.001-06:00

It seems that almost all CAD companies are now investing in history-free CAD technology (direct, explicit). If a design/manufacturing company already owns a very capable CAD tool, why would they purchase a direct history-free CAD tool? What value are they getting from history-free CAD that doesn't already come from their existing CAD tool?

I personally have been involved in the history-free CAD business for many years now. Below I have tried to identify the top ten reasons a company may purchase history-free CAD - based on my observations. Certainly others that have experience in this market may have different observations and opinions. If so, you are welcome to add those as comments to this post.

As usual with a Top Ten list, I’ll start at #10 (least significant) and work up to #1 (most significant).

#10. Functionality

Most companies already have a very capable CAD tool. The purchase of a history-free CAD tool usually has nothing to do with missing functionality in the toolset they already own.

#9. Management of Engineering IP

It may take some time for a company to understand the differences between managing history trees and managing 3D models, but it is significant. People are beginning to understand this and it is starting to influence decisions.
The lifecycle of geometry can be very long. History trees can be rendered obsolete very quickly. Some CAD companies have done this simply by introducing their next version.

#8. Multi-CAD Legacy Data

History trees are proprietary. Geometry is common across all CAD platforms. With mature direct modeling, value can be extracted from any geometry created by any CAD tool.
Companies may add direct CAD to easily extend the value of their legacy data, 2D or 3D.

#7. Teamwork, Collaboration

Teamwork and collaboration can happen more easily when the data in question is a 3D model rather than a history tree. With geometry what you see is what you get. With history trees there will always be an extra layer of complexity.
Improve collaboration and interaction with your dispersed team members, suppliers and partners by sharing data that is clear, simple and based on industry standards.

#6. Company Product and Process Characteristics

Product and process characteristics should drive the usage of a particular CAD technology. Direct modeling may be better suited in the following areas:

Products that demand high innovation with many iterations
Products with short and high speed development cycles
Products with short life cycles
Low volume products
When you just need to get parts out the door as soon as possible.

#5. Large Assemblies

In-context design and optimization at the assembly level is easy and natural in direct modeling, even with 100,000+ part assemblies.
File sizes can be 60% to 80% smaller in direct compared to history-based modeling.

#4. Interoperability

Improve the exchange of engineering data with partners, suppliers and customers that perhaps use other CAD tools.
With direct modeling, geometry is the master, with history-based parametric modeling the history tree is the master.

#3. Speed

Reduce product development cycle times, especially in the concept phase.
Reduce time in the bid and proposal phase.
Reduce time in late stage engineering changes
Reduce efforts and time in preparation for analysis

#2. Ease of Use

Reduce time-to-productivity and improve the flexibility of resource allocation.
Usable by infrequent users. For example:

Analysts for model simplification and preparation for FEA
Marketing for concept review
Bid and proposal team for quick concept development and review
Other non-CAD experts can get value from design data through direct interaction

#1. Flexibility

Review multiple concepts quickly and easily.
Improve innovation by quickly and easily repurposing and reusing existing data.
Improve accuracy in proposal generation by reviewing more alternatives.
More easily respond to customer driven product development.
Complete freedom in the part and assembly modeling process, no requirement for best or common practices
Capture design intent and intelligence in the design only as needed

Many of the characteristics listed above will drive a company to add direct modeling technology as a complementary tool to their existing history-based tool set. It is important for a company to understand workflows and processes to attain highest possible value with minimal disruption. There are a few characteristics however, such as #6, that may drive a company to bring direct modeling technology in as a replacement of their existing toolset. I have recently witnessed several examples of this.

As recognized by thousands of manufacturing companies and several CAD companies, direct, history-free CAD is of high value and is only going to become more prevalent in our industry. If you haven’t already, you should be considering closely what value it can bring to your product development process – most likely your competitors already are.

Paul

Are you a Designer or a Programmer?

2010-07-08T09:40:00.001-06:00

I don’t mean to imply that if you are a “programmer” you are not a “designer” or visa-versa. The question is; as a CAD user do you spend more time designing or programming?

Most CAD users are very familiar with history-based CAD. It is probably what they were initially trained on, and may be the only thing they have ever used. Relatively, very few people have used or understand history-free CAD. They may be familiar with direct editing, but history-free CAD is much more than the direct editing. Every week I personally witness more and more people catching on to the value and benefit of history-free CAD. Most had no clue that such power was available in such an easy and flexible tool.

So what’s the difference? Here’s one way to look at it.

With history-based CAD, users create a “program” typically called a history-tree. This program is created by defining 2D sketches, modeling features, and relationships using specific methods and structure. When the “program” runs, 3D geometry is created. In a history-based system, users do not create 3D geometry, but rather create a program that creates 3D geometry. In the same sense, users do not modify 3D geometry, but rather modify the program that will then create different 3D geometry. The program (history-tree) is the master.

History-based CAD can be a very powerful tool in the right hands, but there are some key requirements and best practices that must be followed. These requirements and best practices are very similar to those found in software development. Here are just a few of them:

Have a clear understanding of the end goal, or intent, before you start
Maintain a clear and consistent structure such that others can follow
Be sure the structure supports the intent
Define small-manageable components that are well organized
Pay close attention to references and relationships

There are also similar challenges with developing a good history tree and developing a good program. Here are a few:

Debugging the program
Translating a program from one language to another
Collaboration at the program level
Reusing an old program that someone else wrote
Managing references and relationships between programs
Managing very large programs

With history-free CAD, users are not creating a program but are rather directly creating and manipulating geometry. Since you are directly interacting with geometry there is no language to learn, no need to plan ahead, no need to understand how the geometry was created or what tool was used to create it, and no need to develop and manage complex references and relationships. What you see is what you get. Geometry is the master. There are certainly challenges yet to be solved with history-free CAD, but the technology is improving rapidly. It is a technology that has been around for many years, but if you haven't tried it recently you need to do so.

History-based CAD is certainly the dominant CAD technology used today for product design and engineering. It is a very powerful tool when properly aligned with the design process. It can also be a very problematic tool when misaligned. One thing to consider is the amount of effort that goes into “programming” vs. “designing”. If the resulting program yields value exceeding effort, then use it to the maximum. Programmatic development and control of geometry can be of high value in the right context. If however the program, including the typical challenges that come with “programming”, get in the way of progress and yield little future value, then consider the alternative.

History-free CAD is being used today by thousands of companies around the globe, as both an alternative and a compliment to history-based CAD. Here are some of the reasons why these companies are using history-free CAD:

If you need a tool that can help you more quickly review a variety of concepts you will want to consider history-free CAD.
If you have a need to involve more people besides the CAD experts in product design, you will want to consider the ease and flexibility of history-free CAD.
If you have a need to interact with geometry coming from a variety of CAD tools, you should be considering history-free CAD.
If your product life cycles are short, there may not be a return on your "programming" investment.
If you need to obsolete your products before your competitors do, you may not have time to develop well structured programs.
If you work with large assemblies (30,000+ parts) you need to consider history-free CAD.
If you need to leverage, reuse and share design data, it is likely easier and more intuitive to do so with 3D models rather than programs.

Paul

(To try out the most mature and capable history-free modeling at no cost, check out PTC CoCreate Modeling Personal Edition: http://www.ptc.com/products/cocreate/modeling-personal-edition-3-0/)

Direct Modeling & Large Assemblies

2010-06-16T09:20:00.002-06:00

Interest continues to grow in our industry for the flexibility and ease-of-use that comes with history-free direct modeling. Unfortunately there is still much confusion out there about just what direct modeling is and what value it adds to the process of product development. One of the many high value opportunities that come with direct modeling is in “large assembly design and management”. Direct modeling technology can offer some unique advantages over traditional history-based modeling that can greatly improve design, interaction and management of large assemblies.

Based on the technology behind direct modeling, large assembly design and management can be fast and easy. As direct modeling does not record the modeling steps used to create the model, memory requirements and file sizes can be considerably smaller than with traditional parametric history-based modeling. With PTC CoCreate Modeling, for example, I have found file sizes to be 60% to 80% smaller than the same model created in most any traditional history-based system. This would indicate that these parts and assemblies will also consume much less memory when loaded.

In a traditional history-based CAD system, an assembly is basically a collection of references and relationships to other individual history trees. These history trees represent individual parts and subassemblies. The history trees can be large and complex. The assembly references and relationships between these trees can be even more complex. With direct modeling an assembly is simply a collection of solid models that are organized in a hierarchical structure. There is no history tree. There are no hidden references or relationships. What you see is what you get. It’s as simple as that.

I’ve been doing some large assembly testing with several different CAD systems. It has been startling to witness how poor many of the most popular CAD tools perform with large assemblies, even with “dumb solids”. The assembly that I am using in this example is made up of 29,455 part and assembly objects. The STEP file of the entire assembly comes out at just over 302mb. The native CoCreate package file of the entire assembly comes in right at 100mb. This is not a large assembly compared to many of the assemblies I have witnessed CoCreate users working with. Most CoCreate users would consider a large assembly to be somewhere around 100,000 to 250,000 parts. (By the way, the native geometry resolution/accuracy of a model developed in CoCreate Modeling is 1.0E-6 mm by default – about 2500 times higher accuracy than any other CAD system on the market, and yet it is still possible to manage these large assemblies.)

Below is a picture of the assembly I have been working with. It comes from a company in Europe. This is a coagulator used in the cheese making process. CoCreate Modeling was used from beginning to end to support the design process.

For the video below I loaded this assembly in its entirety. All parts are loaded as high accuracy solid models. None of the parts were loaded as lightweight, graphics only or in some suppressed mode. Based on the privileges controlled by the PDM system, every part and/or assembly can be quickly and easily modified. As you will see, in-context design is simple and fast, even in the context of 30,000 other parts.

Do you work with large assemblies? Do you enjoy it? Is it easy to collaborate with other team members when working together with large assemblies? If not, perhaps you are using the wrong technology. Remember that in a history based system everything must be programmatically and parametrically controlled; parts AND assemblies. More on this topic in my next post.

Paul

PTC USER World Event 2010, Day 1 and 2

2010-06-09T07:39:00.006-06:00

As you would expect, I attended the PTC USER World event this year specifically to represent the PTC CoCreate family of products. With this post I hope to provide information related to the CoCreate solutions, including the CoCreate sessions and related activities. For those CoCreate users out there that could not attend, we missed you, and I hope this post can give you some sense and feel for the energy and excitement of the event. I know there was much more to the event than what I am going to write about, so please check out some of the other blogs and articles that document the event from other perspectives. An easy way to do this is to follow the hashtag “#ptcuser10” on twitter.

Monday

Day 1 started off with a bang as you would expect. Dick Harrison kicked it off with a high-level enthusiastic overview of business past, present and future. According to Dick PTC is now the fastest growing PLM company with FY10 license growth expected to reach 7x that of its peer group. Dick also talked about some of the changes at the upper management levels of PTC. Dick will be moving to Chairman of the Board for PTC and in his place Jim Heppleman will take over as President, CEO, and COO.

Dick quickly handed over the stage to Jim. Jim reemphasized the fact that "PTC is the fastest growing major software company in the universe, bar none". The enthusiasm and excitement grew in Jim’s voice as he discussed many of the enhancements to existing products and some emerging products. Jim concluded his presentation talking specifically about CAD. The CAD industry almost seems static right now, probably since 2000. And yet there are still unsolved problems related to the role of CAD in product development. Jim summed up these problems in 3 major categories; usability, interoperability and large assemblies. At this point Jim introduced a new initiative that is in the works at PTC. He called this initiative “Project Lightning”. Project Lightning is going to “take Pro/ENGINEER and CoCreate to the next level”. And with that Jim handed the stage over to Brian Shepherd.

Brian went into detail with slides and demonstrations of most all of the PTC PDS solutions. This company has a lot of fantastic products. Some day you really have to check out Windchill 10 … very nice!

During Brian’s presentation we even got to see a clip of CoCreate Modeling v17 doing some of its direct modeling magic. It was great hearing about and seeing all of the new innovations that PTC is bringing to the market – but I was most interested in this “Lightning” thing.

Brian finally got around to talking about Project Lightning. He referred to it as “The future of CAD”, and “A fundamental breakthrough”. I could try to summarize the talk but it would be better for you to hear it directly from Jim and Brian. Check it out here: http://www.ptc.com/project-lightning/

I realize there is not a lot of detail being shared right now, but you can know for sure that by bringing the people together that invented parametric modeling with the people that invented direct modeling with PTC’s PLM expertise … “break-though” might be an understatement. Mark your calendars: October 28th 2010.

Breakout sessions started right after a quick break. Korie Carter and Scott O’Brien of Tensor Engineering kicked off the CoCreate related content. This company develops the detail drawings necessary to manufacture the steel and construct the bridges. That is a terrible simplification of the incredible engineering challenges that they must solve along the way. And they solve these problems with many innovative tools, many of which they have developed themselves. One of the tools they use is CoCreate Modeling. Both Korie and Scott showed some amazing automation tools they have developed with extensive use of the parametric modeling capabilities of CoCreate Modeling – that’s right “parametric modeling” in a history-free direct modeling system. It was fascinating to see the engineering challenges that they have solved with this technology. They have refined the technology down to a one button solution. Amazing!!

After Korie and Scotts presentation, Chris Whitman, technical specialist for the CoCreate solutions and myself delivered a presentation focused on providing an introduction to CoCreate Modeling. The room was full of people that had little or no knowledge of CoCreate. I assume that the talk about Project Lightning may have sparked some of this interest. We spent very little time with slides but rather took turns showing some demonstrations of what direct modeling really is in the context of a mature, robust and very capable tool like CoCreate Modeling. We provided 4 basic demonstrations. One showing some quick and easy conceptual design of a fixture, applying design intent and parameters as needed. And then ending with some simulation of the fixture: Video

The next demo was of the conceptual development of a computer mouse using some high tech surface editing technology only found in CoCreate Modeling: Video

Chris then demonstrated some amazing interoperability by loading some IGES files and doing things with imported geometry that most people assume can’t be done. In CoCreate Modeling you work with imported geometry as you would with native data – no difference. We leverage the intelligence already built into every solid model regardless of where it comes from. Even imported sheet metal parts can be modified and flattened with appropriate k-factor.

I ended the demonstrations by loading a 30,000 part assembly into CoCreate Modeling, something that most CAD sales people would never do in front of their customers - and actually something most history-based CAD users have never done. I loaded the complete assembly in its full form with all parts loaded as high accuracy (1.0E-6mm) solid – modifiable – parts. The load took 50 seconds. This is a 300mb STEP file. I then proceeded to make some design changes in many areas of the assembly … in-context with 30,000 parts. And this is a relatively small assembly compared to what many of our customers work with on a daily basis.

We basically talked about “ease of use, flexibility, interoperability, and large assemblies”. Sound familiar?

The next session was designed to give existing CoCreate users a detailed look at all the various enhancements of CoCreate Modeling version 17 . However the full room did not only include existing users, but more people that wanted to learn more about CoCreate. Chris and I had to balance the time between giving the existing users some useful information, but also help the many other people understand the basics of what direct modeling is. Thankfully our users engaged in the discussion, and were probably more effective than Chris or I in helping the others understand the technology and value of CoCreate. It was an amazing session. It is always fun watching peoples expressions when the begin to realize and understand what they are seeing – they usually can’t believe it at first.

Every other minute Chris and I had in the day was spent at the CoCreate booth in the exhibit hall. People were waiting in lines to see demos and to get to know better what this CoCreate thing is. It was a lot of very hard work, but so much fun to see the expressions on people’s faces. Many assumed for whatever reason that CoCreate Modeling is some low-end 3D sketch kind of thing, with some inferior geometry kernel with very little capability. It only takes about 2 minutes to change this perception as we demonstrate solutions to complex design problems that they obviously had never seen before – including high-end complex surface editing, and interaction with large assemblies that they could hardly comprehend. 100% of the people that were able to get a demonstration and talk with us, left with a complete different perspective on CAD – and all wanted more. I think we will be very busy in the weeks and months to come.

During booth duty some of my media friends stopped by to say hi. It was great to talk with Leslie Gordon from Machine Design. Thanks for coming by Leslie – let’s continue our discussions. Also Kenneth Wong stopped by for a quick demo and some discussion. (I want a copy of that picture we took, Kenneth.) You can check out Kenneth’s coverage of the event at his blog: Kenneth Wong’s Virtual Desktop

Tuesday

On Tuesday Chris taught two classes on CoCreate Modeling. I unfortunately missed the keynote as we were setting up for the classes. The first class was for existing users to get hands on experience with the new CoCreate v17. We saw many big smiles and raised eyebrows as Chris showed the new v17 enhancements and users got to try them out. This is one of the most significant releases we have had in years.

The next class was an introduction to CoCreate. The room was full of people that were excited to get their hands on CoCreate for the first time. It always takes a little while for people to understand that when working with CoCreate you work directly with geometry. There is no history tree. Modeling operations are not recorded. There is no need to be concerned with how you create the geometry. At first they seem to be cautious or nervous about creating the geometry in the wrong way or perhaps breaking some reference or relationships with an edit. And then in a few minutes “the lights come on” and they realize … it doesn’t matter.

I wish we could have stayed another day and met more people and provided more demonstrations, but we had to get back, and now I am on the airplane writing this and reflecting back on all the fun, and great people that I got to meet. I fully expect to see you next year in Las Vegas, where perhaps we won’t be talking about “The future of CAD” but rather “experiencing” it.

Paul

CoCreate at PTC/USER World Event 2010

2010-06-02T14:51:00.009-06:00

The CoCreate products will again be represented at the PTC/USER World Event 2010. I will be there and have 2 sessions that I will be presenting along with one of our product experts. The two sessions are detailed below:

Introducing CoCreate Modeling, the World's #1 Explicit Modeler

This session is specifically for people that have little or no experience or knowledge of CoCreate Modeling, or history-free explicit modeling. I will talk a bit about the technology, but we will be spending most of the time showing you the technology. You will see some fascinating demonstrations including things that you have probably never seen a CAD system do before. Then we will review how this technology can complement your design environment and add value in several areas of product development.

Introducing CoCreate 17.0: Simplicity of 2D, Power of 3D

This session is tailored more for the experienced CoCreate users. We will be going into much detail on what is new in V17. This will include many demonstrations of the product features and capabilities. We plan to have a highly interactive session with the CoCreate users.

Korie Carter and Scott O’Brien of Tensor Engineering will also be delivering a very interesting presentation. Their presentation is titled: “Automated 3D Field Splice Generator”, (whatever that is). You may not have much to do with bridge design, but you should see what these people are doing with CoCreate Modeling and how they are using history-free parametric relations to capture design intent and solve some very complex design problems. You gotta check this out.

For more detail on where and when these presentations are occurring go to: http://www.ptcuser.org/2010/cocreate.html

CoCreate Modeling Hands-on-Workshops

We are also providing some informal hands-on-workshops on Tuesday. These were last minute additions to the schedule and as such you may not find much information about these in the formal agenda. Here are the details:

Tuesday, June 8 in the Wekiwa 5 room

9:45 to 11:30: V17 hands-on update training. For experienced users that want to learn more about the v17 enhancements.

1:00 to 2:45: Getting started with CoCreate Modeling. For people that have little or no experience with CoCreate Modeling. Come and try it out. We’ll have some fun with it.

CoCreate in the Exhibit Hall

I'll also be providing demonstrations in the exhibit hall with some of our other product experts. Be sure to come by and see us.

Keep track of the activities on twitter with hashtag #PTCUSER10.

Paul

Explicit Parametric Concept Design

2010-05-19T06:00:00.008-06:00

I know that most of you will consider the title of this post as being a contradiction in terms. I hope to show you otherwise. We are certainly seeing the makers of history-based parametric CAD tools attempting to add explicit like or direct modeling type functionality to their history-based systems. Unfortunately many complications can evolve in the model when direct geometry edits are made to a history-based model. Maybe someday the issues will be worked out. While this work is going on, makers of explicit or direct modeling systems are adding parametric modeling capabilities to the history-free model. Adding, managing and controlling “design intent” are not capabilities exclusive to a history-based modeling tool.

In the video example below I am showing some quick concept design of a fixture assembly, but while in the process I will capture some design intent as needed. Again in this case I am using CoCreate Modeling from PTC.

You will notice in the example that it makes no difference how the model is created, or how the assembly comes together. There is no up-front planning that needs to be done. History-free “design intent” has no dependency on how the models or assemblies were created or structured. As a matter of a fact, it makes no difference where the geometry actually comes from; IGES, STEP or even a 2D drawing. I can just as easily add design intent to imported models as I do with native models. Also, another user can easily interact with the design intent with no knowledge of how the model was created or how the intent was structured. The parametric solver in CoCreate Modeling is a synchronous solver. It is not a linear solver as would be the case in a history-based system. As such there is not dependency on the order that constraints and relationships were created. They are solved simultaneously.

You will also notice in CoCreate Modeling that constraints and relationships are not always necessary – and in many cases redundant. A mature explicit history-free modeling system must understand and leverage the properties of the B-Rep solid geometry to be of any value. If it does, it can use these properties intelligently to recognize geometric properties and greatly simplify the design intent solution.

I first hope you noticed how easy and fast it is to create and manipulate geometry, with no need for up front planning. Secondly I hope you noticed that design intent can be added independent of the modeling process.

I know most all CAD companies are trying to figure out how to provide their customers with the “best of both worlds” (history-based parametric & history-free explicit/direct). Will the “best” eventually come from a history-based system that provides direct editing? Or perhaps will it come from a history-free system that provides parametric capabilities?

Paul

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Some ways to learn more about CoCreate Modeling:

I'll be presenting at a live webinar May 27th at 2pm EST: CoCreate Modeling: Conceptual Design and Beyond
If you are planning to attend PTC User World Event, please stop by our booth, or attend one of our sessions.

The Growing Power of the IT Department

2010-04-21T07:26:00.000-06:00

As I mentioned a few times before, in my current position at PTC I get the opportunity to visit many companies. I just returned from a trip to Europe where I was able to visit two very large companies. One interesting thing I am recognizing is the growing power of the IT organization, especially with large companies. I’m sure one of the reasons that this happens is that as a company grows AND as they become more dependent on computers, the internet and infrastructure, a good portion of the company budget goes to IT. When I first started in the industry I don’t even think the term “Information Technology” existed, we were kind of on our own with our big CAD workstations. When the concept of the IT organization did emerge, it was considered a “support” organization”, and it provided a very welcomed and needed function. For many companies IT has now grown into something entirely different.

I am usually visiting these companies to make recommendations in the area of product development productivity. I do my best to follow what is suggested in the diagram below.

A company’s business drivers and key business objectives should drive and guide process, and process should define the supporting technologies. If we do this correctly the technologies will enable and support the defined process improvement initiatives, and the improved processes will deliver to the business drivers. In too many cases I’ve witnessed situations where companies have tried to force fit technology into the process with little regard to the process and business, rather than working from top to bottom and back up as indicated by the chart above. This often results in chaos in the deployment project and overruns in the project budget.

So where does the IT department fit into all of this? Chances are that they will be responsible for deploying the technology. Are they also responsible for determining what technology best supports the process and yields highest return at lowest cost? If so, does your IT department understand the product development process enough to make the appropriate choices? How is success measured with a technology deployment that impacts product development?

It is interesting to witness IT’s involvement and influence within the context of product development. It can range from complete and dedicated “support”, to complete and dedicated “control”. In most cases there is a healthy balance and interaction between IT and Product Development, but not in all cases.

Regardless of IT’s roll in the acquisition of technology, where does “productivity” of Product Development fit into the decision criteria when acquiring tools for your product development organization? What are your observations?

As a representative of a company that sells product development technology, a key to success is in knowing who the buyer is. It’s fascinating that in many cases our “buyer” is IT.

Paul

SolidWorks, the CATIA Kernel & Direct Modeling

2010-02-09T08:35:00.001-07:00

In my last blog post: Technology and the Product Development Process, one of the readers asked a great question:

Paul, I know it is coming out in bits and pieces, but at SolidWorks World there is a good deal of reporting about solidworks enhanced direct editing, and even some speculation that solidworks is switching to the catia kernal. What would this indicate about the future of direct modeling, and cocreate's place within it?

This question opens up many good discussion points, and I apologize in advance for the length of the post.

It is interesting to see discussion about the CATIA kernel in context with direct editing. A geometry kernel has little to do with whether a CAD system is history-based or history-free or has direct editing or not. Direct editing does demand more of the kernel than history-based modeling does, but I see no evidence that the CATIA V6 kernel brings anything special to direct editing. CATIA certainly has direct editing capabilities but much of what you see in CATIA Live Shape is very similar to Instant3d in SolidWorks and Dynamic Editing in WildFire. As stated in this video: CATIA V6R2010 User experience, CATIA Live Shape allows you to “manipulate feature parameters directly on the geometry itself instead of editing through panels and keyboard input” - you are not directly editing geometry but rather dynamically manipulating feature parameters that are managed in the tree.

So what about direct editing in SolidWorks and the future of direct modeling?

People still seem to have the idea that somehow we are going to be able to combine these two technologies and get “the best of both worlds”. Since it is not possible to “record history” and “not record history” at the same time, there are only a few approaches that developers can take. Several CAD companies have already made attempts at combining these technologies and several others continuing to work on it – but so far none have been able to provide “the best of both worlds”. First of all, what is “the best of both worlds”? Here is my attempt at an answer. Others are welcome to add to the lists:

The best of history-based:

Some claim that the history tree is the best way to capture design intent (I disagree, but that's personal preference).
Some may claim that the history-tree is the best way to manage and maintain associativity (however associativity does not require a history-tree).
History trees allow for faces to be consumed by an edit, and at some point in the future these faces can be exposed based on another edit – I guess this could be considered a best, not sure.
History-based CAD forces a very specific modeling process and behavior. This could be good in some cases.
Most of these systems are very mature with much depth and breadth in functionality – although this has nothing to do with being history-based, it is relevant.

What are some of the other bests of history-based modeling? I’m running out of ideas. The list used to be much longer but it continually gets shorter with the rapid advancements in history-free modeling.

The best of history-free:

No need to throwaway models due to bad trees – all geometry is of value
No regeneration/re-compute issues
Can manipulate geometry with no regard to how it was created in the first place
Natural in-context, top-down, bottoms-up, what-ever design (flexibility)
No need for part modeling and/or assembly modeling modes
No restrictions or complications related to the use of certain modeling and editing functions (unite, subtract, intersect)
Add and remove design intent as needed – on native or non-native geometry: An Example
Easy to reuse and leverage ANY geometry from ANY source, full interoperability
Large assembly modeling/management (simply much less data to manage)
What-you-see-is-what-you-get

Those are a few of the bests of history-free modeling. Of course not all history-free CAD systems are as mature as others, so the level at which you can realize these bests today will vary – although the technology is rapidly improving. What’s interesting here is that IF there is any hint of a history-tree in the CAD system, you will never realize most of the bests in the history-free list.

Equally, if there is no history tree you will never… I can’t think of anything. Maybe you will never be able to consume a face and at some point get it back.

Below is a quick review of some of the industries attempts at getting “the best of both worlds”:

Siemens, (NX, Solid Edge) – They simply have made the two technologies, (history-based/history-free) available under the same UI. In this case it is still one or the other. And when you choose history-free, the system lets you know that the tree and all the intelligence built into the tree will be lost – forever. If the history-free capabilities were more robust and complete most users may not care, but that is not the case - yet. In the history-free side of the product, Siemens has done a nice job at combining parametric control with history-free modeling with their Live Rules, but they have not combined history-free with history-based.

Autodesk, (Inventor/Fusion) – Inventor has already had direct editing for several years. Fusion is just another history-free tool, although not a very good one - yet. The Change Manager will recognize direct edits and translate them back to the history-tree in the form of a feature change or an added direct edit to the bottom of the tree. In the end, all of this functionality may be under one UI and transparent to the user, however the end intent is to maintain the history-tree. Unfortunately the Change Manager will never resolve problems that may show up in the history tree, and because they are maintaining the history tree most of the benefits of history-free modeling listed above will never be realized. The Change Manager functionality will also result in design intent being automatically changed, i.e. lost.

SolidWorks – SolidWorks has also had direct editing for a few years now. I haven’t seen this new stuff in person, but I assure you that there is nothing magical about it. They are either throwing away the history tree, or they are keeping it intact. Those are the ONLY two choices that are available. Most likely they are keeping the history tree intact, as SolidWorks will probably always be history-based. The new stuff is either an extension of Instant3D or it is direct editing that is, like Fusion and the Change Manager, being captured in the tree either as a feature edit or an added direct edit in the tree. As with Fusion and the Change Manager, most all benefits of history-free modeling will not be realized – as there is still a history tree.

PTC, (Pro/ENGINEER) – Even at PTC there is talk about combining these two technologies. In WF5 we are starting to see much more direct editing. Again, however, the same “laws” apply. Either the history tree is thrown away or it is kept intact. With Pro/E I am quite sure there will always be a history tree no matter how much direct editing they put into the system – and again, most of the benefits of history-free modeling will not be realized.

IronCAD – Ironcad was the first CAD system on the market to make a good attempt at combining these technologies. Although it was only recent that they exposed the history tree to the UI IronCAD has always been history-based, even before it was IronCAD (Trispective). Notice the references to the "tree": Introduction to IronCAD 2009. Their use and management of 3D primitives (3D shapes/features with no sketch) make it possible to directly edit these features, the edit simply changes the primitive. The primitives must be ordered in the tree. If the model is a single feature model (history-free) the direct editing capabilities can apply to the entire model. These direct edits are limited only by the robustness and predictability of the direct editing capabilities, as is the case with direct editing in any CAD system.

In all of the cases mentioned above the history-tree is fundamental to the system, regardless of any add-on functionality or fancy user interaction. As such most of the bests of history-free modeling cannot be realized. I understand that many of the history-free examples on the market still do not provide the depth and breadth of many of the mature history-based CAD systems, but this is quickly changing. History-based modeling is mature. We may have already hit the limits of what we can do with this technology. On the contrary, even though we have been playing with history-free modeling for many years, there is still so much more that we can do with it. It is relatively immature.

SpaceClaim posted record growth numbers for 2009. Kubotek claims that 2009 was their best year ever. As part of HP, CoCreate and now PTC CoCreate, I can tell you that we have never experienced the level of interest in the product and growth that we are experiencing right now. CoCreate's place in this market is very solid. To think that some combination of history-based modeling and direct editing is going to slow this growth is quite short sighted. The future of history-free modeling is very bright and there is nothing you can do with a history-based CAD system that will change that. In reality the only way we will ever get even close to “the best of both worlds” will be to start with something that is fundamentally history-free.

Paul

Technology and the Product Development Process

2010-01-26T15:10:00.005-07:00

Everyone seems to have an opinion about CAD technology and what is best – including me. But I often question what it all really means to product development. In my current position at PTC I get to review and analyze the product development processes of many companies – all of which have a different mix of technologies that support, to some degree, their product development process and product characteristics.

In every product development organization there are vocal users that think they know best – and in many cases they do. There are even IT professionals that think they know best. But I also find that many of these people are focusing their arguments and discussion based on their own individual circumstance, experience and needs. Many times I find that we are ignoring the bigger process picture. Although the user experience is important, there is much more to consider when evaluating our product development tools.

Consider the process of innovation or perhaps "concept design", and also consider the process of detail design. There is a significant difference between innovating and detailing. There is no hard line that separates the two, and innovation may actually occur throughout the entire process. However, these are two different disciplines – or “processes”. Consider the technologies that might be best suited for these different disciplines. What technologies best support the requirements? Of course to have a real meaningful discussion we would also need to know what the overall business drivers are and how they impact the process of developing products. We would also need to know much about the characteristics of the products that are being developed as well as the dynamics and structure of the product development organization itself.

If you are person primarily involved with innovation and concept design, you have different requirements than someone that is more involved with detailing and documenting a design. If your company is dependent on innovating products there will be different requirements than that of a company that is more focused on configuring products. Some CAD tools may support both disciplines but many don’t. Some PDM tools may support one process better than the other. Consider some of the requirements for innovation and concept design (just to name a few):

The ability to consider many different ideas (flexibility)
Reviewing old ideas to come up with new ideas (leverage, reuse)
Interacting with others at the idea level (teamwork, collaboration)
Analyzing and comparing ideas

What type of CAD system would do best in supporting the above requirements? It is true that with history-based modeling you are strongly encouraged to “plan ahead” - for a variety of very good reasons. Another term for “planning ahead” is “concept design”. What about detail design? Perhaps your history-free tool doesn’t have the desired capability for capturing design intent or “documenting” the design. Depending on your processes and product characteristics, this capability may bring value.

What about your data management practices and tools? Do they support the requirements of innovation? How do they support the need for flexibility, access and teamwork? For detail design, do the practices and tools provide the proper control?

Next time you are having a discussion about which tool is best, please consider and clarify the context of your evaluation and opinion. It can make a big difference. If not, your opinion could actually lead to a serious mismatch between tools and process. If the tools fail to support the process, the process will fail to support the business.

Paul

Direct Modeling and Freeform Surfaces - An Introduction

2010-01-05T08:15:00.000-07:00

In a recent post titled “Predictability with Direct Editing – Part II” I included a video that very briefly shows the creation of freeform surfaces by using a direct edit. Since then I have received several questions and interest in understanding more about how freeform surfaces can be developed and modified using direct modeling technologies.

Freeform surfaces are surfaces that are non-analytic, i.e. they cannot be defined as a plane, cylinder, toroid or cone. These surfaces are defined using Basis-Splines (B-Splines) or Non-Uniform Rational Basis-Splines (NURBS). There are many surface modeling tools on the market that specialize in the creation and manipulation of freeform surfaces. Many of these do not generate volume solids, but rather interact directly with the surface geometry. This technology has been around for many years. There are also many solid modeling systems that have freeform surface design capabilities. This technology is a bit more complex in that connectivity must be maintained to form a solid, even during editing.

History-based modeling has simplified the problem of freeform surface design in a solid model by making the development and modification of these complex surfaces “history-based”. In other words, with history-based modeling you capture the process of creating the surface in the history tree. Rather than directly manipulating the 3D surface, history-based modeling allows you to go back to the original sketches and parameters that were previously captured in the history tree, modify them as necessary, and then regenerate the model. With this technology there is no need to directly manipulate the surface and try to maintain connectivity. It greatly simplifies the problem – that is, IF you create the part correctly in the first place.

With history-free direct modeling there is no history tree. As such surface design and manipulation can be more complex. The system can certainly provide a variety of surface creation capabilities, but when it comes time to modify the surfaces there are no 2D sketches to go back to. The interaction must be done directly on the surface while maintaining connectivity and continuity – in a predictable way. It is certainly not a trivial task and there are still many challenges, although progress continues.

The video below is the first of several videos that I hope to do regarding history-free solids-based freeform surface design (or something like that). This first video is a simple example that only shows a small subset of the freeform creation and editing capabilities. As usual I will be using CoCreate Modeling for these videos, but if the other makers of history-free direct modeling systems (Spaceclaim, Kubotek) want to add to this, I will be glad to include links in other posts.

Paul

2009 - The Year of … Confusion?

2009-12-28T09:20:00.001-07:00

History-based, parametric, history-free, direct, explicit, synchronous, dynamic, instant...

Over the last few years CAD companies have introduced many new terms as they have announced new product capabilities. Most significant are the capabilities related to direct geometry interaction and manipulation. The industry is becoming more familiar with the concept of history-free modeling (direct modeling, direct editing). As the awareness grows, the industry is trying to understand just what this technology means to the product development process. Unfortunately for many it’s still a bit confusing.

Is this history-free direct modeling technology complementary to our parametric history based environment or is it perhaps a replacement? Being part of the CoCreate organization inside of PTC I have witnessed many companies purchasing CoCreate for a variety of reasons. Many have completely replaced their old history-based environment with CoCreate, but many have also added it to their history-based environment as a complementary tool. In either case many companies are seeing significant benefits with history-free direct modeling.

It can certainly be a bit confusing for product development organizations to understand how this history-free technology can bring value and how it fits into the process. The confusion I am referring to is for the most part a result of how many CAD companies are positioning this technology. For example:

Siemens introduced Synchronous Technology in 2008. Today they continue to claim: “Synchronous Technology unites parametric and history-free modeling”

In 2009 Autodesk gave us a preview of their Fusion technology. They claim that Fusion “unites direct and parametric workflows within a single digital model”

I have had many discussions with people that have been confused by these statements.

Synchronous Technology does in fact unite parametric “control” with history-free modeling, to a certain extent. But unfortunately most people consider parametric modeling synonymous with history-based modeling. Synchronous Technology absolutely does not unite history-based modeling with history-free modeling. The two technologies may sit under a common UI, but they are very separate. Either the user is in a history-based mode, recording every modeling operation -OR- they are in a history-free mode where modeling operations are not recorded. It’s one or the other.

Autodesk does an even better job at confusing the situation. In Autodesk’s statement above they are in fact referring to history-based modeling when they use the term “parametric workflow”. They are also referring to direct modeling in the term “direct workflow”. My first source of confusion is in the concept of a “direct workflow”. There is actually no such thing. Certainly with history-based CAD there is a workflow to consider as every step you take is recorded and will impact the future use of the model. No such concept exists with direct modeling.

The Autodesk statement also suggests the possibility of uniting history-based modeling with history-free modeling with the term “single digital model”. What Autodesk has done with Fusion, a history-free tool (that creates a new file), is to provide technology that can analyze a history-free model coming from Fusion in such a way that the history structure and features of a history-based model, back in Inventor, can be updated based on differences that are found in the history-free model (two separate data models). My primary confusion with this concept is that if in fact the edits are possible in Inventor, then why do I need Fusion? Trying to create intelligent and properly structured history trees from history-free solids is nothing new, but Autodesk has made some progress in this area. I for one am a bit skeptical of this technology as there are just too many assumptions that the system must make to automatically create a useful tree structure, or edit an existing one. Not to mention getting a useful tree structure that would actually match my design intent.

Much of the confusion I see out there comes from the idea that somehow, some way, sometime, history-free modeling and history-based modeling will merge. Recently I watched someone draw two lines on a chart, one representing history-based modeling and one representing history-free modeling. At some point on the drawing the two lines merged into one. The merging of these two technologies is actually not possible. A CAD system is either recording the modeling steps or it is not. It is one or the other. The technologies can coexist, but it must be well understood how the resulting data will be used and managed.

Consider the intellectual property (data) that is created with a CAD tool. If the CAD tool is recording the modeling steps (history-based), the record (history-tree) is the critical IP. Without the history tree, the value of the model is considerably lower. If the CAD tool is not recording the modeling steps (history-free), the 3D model is the critical IP, history trees are of no value. Most any 3D model of reasonable quality can be considered valuable IP with history-free technology. That is not the case with history-based modeling.

While the technology to create history from non-history may improve a little, history-free modeling technology is continuing to improve - a lot. As history-free technology improves the value of the history tree declines. Eventually we may be wondering why we need a history tree, rather than trying to figure out how best to create, structure, modify and manage them.

This post probably does little to clear the confusion, but maybe we can work on that more in 2010.

Have a happy and successful new year!

Paul

Predictability With Direct Editing - Part II

2009-11-18T14:30:00.006-07:00

In my previous post titled Predictability with Direct Editing I showed a simple example of what it means to get expected and predictable results with “direct” or “explicit” editing. It was a simple example in that the geometry was mostly analytic – planes, cylinders and cones. With this example I am adding much more complexity in that most all surfaces being represented are complex b-spline surfaces. This example will greatly push the limits of direct editing.

As I have mentioned before when pulling on faces using direct editing, the system needs to extend or shrink the adjacent faces, but should also properly take into account rounds, fillets and chamfers. This gets much more complex if the adjacent faces happen to be complex freeform b-spline surfaces. How well will the system extend or trim the surfaces? Can you get predictable and consistent results?

For this article I also created a simple video to show the example. I start with a simple cube and then using direct editing capabilities to deform several of the planar faces. If you are trying this on other CAD systems you may have to use other methods to get the complex surfaces, however it shouldn’t matter how you create the surfaces. Once you have them just add the rounds and chamfers to get the basic shape.

Hopefully the topology of your part matches the one in the picture. Pay close attention to how your CAD system creates the chamfers. Are they accurate? It’s a bit surprising how some modern CAD tools treat chamfers.

Now let’s try some direct editing.

Try this example on your favorite CAD tool. Can you get expected and predictable results? How well do the surfaces extend? Is chamfer and blend sizes maintained? Are tangencies maintained and accurate? Are the surfaces extended in a logical and predictable way? Are the chamfers and blends order dependent? Live rules and parametrics can help control change, but if you can’t get through the basics of change they add no value.

Even though I considerably increased complexity with this second example, besides adding blends and chamfers I still did not change the topology of the model. So perhaps sometime in the near future I can bring it all together, including complex topology changes, with a realistic part.

Paul

Inventor Fusion Preview II – The Fusion

2009-11-02T07:00:00.006-07:00

I too was given the opportunity to see Inventor Fusion Preview II. I was a bit shocked when Autodesk invited me. I told them again that I work for PTC, but they still wanted to show it to me. I guess attention is attention. So here’s how it works (as near as I can tell):

The demonstration started with a history-based model that was created in Inventor. In this case the model was fairly simple and included only a few features. This part is saved as a native Inventor file.

In the example given, another user would load the Inventor file into Fusion to make some modifications to the file using the direct editing provided in Fusion. When the Fusion user is satisfied with their edits they can save the modified part as a new Fusion file.

Back in Inventor the designer may be notified of some suggested modifications to the design of the part. The designer would then load both the original Inventor model and the modified Fusion model. When this is done, Inventor will scan the topology and geometry of both parts looking for differences between the two models. After the scan, edits (modifications, deletions, additions) will be highlighted by different colors. Inventor will provide a list of the modifications that are being “suggested” by the modified Fusion part. These modifications can then be accepted or rejected.

If accepted, Inventor will look for the effected features in the history tree (sketches or parameters) and will drive edits to these features updating them based on the recognized changes from the Fusion part. Accepted edits that cannot be accommodated through modifications of elements in the history tree will be captured as new features at the bottom of the tree. The end result is a modified history tree based on direct edits from Fusion.

Basically the Inventor Fusion technology is identifying differences between two B-Rep solids, recognizing which history-based features need to be edited, added or removed, and then applies the accepted modifications to the history tree.

There are two basic technologies at work here. The first is the scan. Technology for scanning two B-Rep solid models and geometrically comparing then is nothing new; it has been around for many years. CoCreate for example has been using this technology for many years to provide version compare and change management for its users. It does have its limits however. Robust direct editing can result in a model that is completely unrecognizable from the original by even the best compare tool, especially if the topology of the model changes. I can conceive of many examples where this scan will result in inaccurate results. If the scan delivers inaccurate results, the second technology is meaningless.

The second and most significant technological contribution that is being made with Inventor Fusion is in taking the results of the scan and identifying what feature, sketch or parameter from the history tree must change to provide the same geometrical results of that of the part modified with Fusion. It is basically attempting to map a “geometry” modification back to an element in a history tree. In some cases, such as the blend and chamfers from the above example, it can remove a history based feature and/or add and organize new features as needed. (I’m not sure if it can change the order of features yet.) If it can’t make sense of the Fusion modification, a new element will be added to the tree representing the faces involved in the direct edit. When the history tree is regenerated, the resulting model should geometrically match the Fusion model. It’s an interesting technology and I hope to have a chance to dig into it a bit more. I am still skeptical about how well it can create and order new features, in a way that will support the design intent. Time will tell.

I am a firm believer that technology is only an enabler to process. If it doesn’t enable, or bring value to a process, it is useless. So the question going through my mind is; what processes, or use models, can be enabled with the Inventor Fusion technology?

Above I roughly outlined a process. It could go something like this: Perhaps a designer is working on a plastic part. The design has progressed to the point where a review with the tooling supplier is required. The 3D model as an Inventor file is sent to the supplier. On review the supplier has some suggestions to make for this part to be better suited for manufacturing. Maybe for some reason the tooling engineer prefers using Fusion rather than Inventor. Using Fusion, direct edits are made to the model to communicate the suggested modifications. The modified 3D model, a Fusion file, is then sent back to the designer for review. The designer desires to keep the native Inventor data up-to-date and so loads both the original Inventor model and the modified Fusion model into Inventor. The suggested modifications will be highlighted for the designer to see and review. The designer can then either accept or reject the suggested modifications as needed. Accepted modifications will drive updates, deletions and additions to the history tree keeping the native history tree up to date.

I am trying to come up with other use models. Help me out.

When and why is it important to have direct editing when your CAD system of choice is history-based? Some of the more common reasons include the following:

1) I need to make some last minute modifications to the model, but the structure of the history tree does not support these required modifications. I will either need to rebuild the part or use direct editing. Will Inventor Fusion technology help with this? Most likely not. If you can’t make the edit in the tree manually, it is very unlikely that the system will be able to make it for you automatically based on a modified B-Rep model. I asked Autodesk during the preview what would happen if the Fusion direct edit would invalidate a feature in the Inventor history tree. Also, what would happen if the history tree structure in Inventor would simply not support the suggested Fusion edit? Here is an example they showed:

They demonstrated that in those cases the modified faces would simply be captured as new features (sculpt) in the history tree – very similar to adding a direct edit to a history-based model in other history-based systems. So, if the edits found in the scan/compare cannot be translated to a feature in the Inventor history tree, new elements are simply added to the tree as new features; as is usually the case when doing direct edits in any other history-based environment. In this case the result would be very close to the same with or without Fusion.

2) I want to use direct modeling for concept design because of the flexibility, but then want to use my standard history-based tool for detail design. Will Inventor Fusion technology help with this scenario? I am not sure. I would like to check into this more. What will Inventor do when a part that was originally created in Fusion is loaded into Inventor, with no counterpart from inventor to compare it to? Will it only yield a single feature solid as has always been the case, or will it attempt to do what FeatureWorks does in SolidWorks?

3) Preparation for FEA is often a good use for direct editing with history-based data. Perhaps we want to simplify the model by removing some features. Many times this removal process can be very painful in the history-based system that was used to create the part in the first place. In many cases the references and relationships are just too complex to make the necessary edits. As such many companies are choosing direct editing to support this process. Will the Inventor Fusion technology support this process? First of all, there is probably no reason to push the direct edits back to the native (master) Inventor model. We only need this data for FEA. Secondly, I do not see that the direct editing within Fusion is robust enough (yet) to support the sometimes very complex process of simplification.

Perhaps you can think of process or “use cases” where direct editing of a history-based model is of benefit. And then consider when and how the Inventor Fusion technology can bring value. When is there value in relating a purely geometric modification back to an element in the history tree? Autodesk has certainly introduced some new and interesting technology with this second preview. Now, how will we use it?

Paul

Predictability With Direct Editing

2009-10-12T08:00:00.002-06:00

I have written a few times about the need for predictability and getting expected results with direct editing. In the recent past I have received a few questions about what I am referring to with regards to “predictability”. So with this post I hope to explain this a bit more.

Direct editing technology gives us the ability to interact directly with geometry. The alternative is "indirect editing” which involves parameters, dimensions, variables and so on.

When we use direct editing technology we are usually moving geometry around by directly selecting the geometry that we want to move and then defining a transformation by pulling, pushing or rotating about a direction or axis. The CAD system then takes over. It should provide results that the user is expecting, but that is not always the case. When pulling and pushing on faces there are usually a variety of solutions that can be derived. The big question is; what happens to the adjacent faces of the face that we are moving. Are they stretched? Are faces added or removed? What happens to the pulled or pushed face? Does it retain its shape and size or does it change?

For this article I thought it might be best just to create a video of a simple example. You can easily recreate this example in your favorite CAD system and compare direct editing results. Direct editing is now available in both history-based systems (parametric modeling) and history-free systems (direct/explicit modeling). So you can try this example in most any CAD system. Be careful not confuse functions like “Instant3D” or “Dynamic Modification” with direct editing. These type of functions are dynamically manipulating parameters, dimensions, variables and sketches – i.e. “indirect editing”.

I’ve actually tested this simple example in about 7 different CAD systems, but I will only show you the results using CoCreate Modeling since I now represent this product. Other experts can try the example on their system of choice. The key is to use the default settings that the CAD system gives you. There are certainly options to functions that will give different results. What I was interested in while doing the test was to understand the default behavior of the CAD tool.

Here are the steps to create the example:

Create a block. We are not concerned with size for this example. Only topology.
Taper two adjacent faces on the side of the block. Any angle will be fine
Add a round/blend to the edge joining the two tapered faces
Add a round/blend to the top back edge, any size as long as they don’t touch each other
Add 45deg chamfer, width to be less than round/blend radius
Add a hole through the center of the block
Add a chamfer to the top of the hole

Hopefully the topology of your part matches the one in the picture.

Now let’s try some direct editing.

Try this example on your favorite CAD tool. Can you get expected and predictable results? Do you have to use box select? Do you have to use other options to the command to get it to work or did the default behavior deliver the expected results?

One of the things that you may have noticed in the video is that CoCreate Modeling understands what blends and chamfers are from a mechanical design point of view. It does this by interrogating the B-Rep solid model and identifying conditions that are important to mechanical design. It is not just a geometry making machine. This is where “maturity” comes in with regards to a Mechanical CAD tool (perhaps another topic for a future article). Unfortunately many CAD tools are just geometry making machines with little regard to what engineers are really trying to do.

Of course this simple example and the edits I make are easy to do in a history-based system by changing the base feature, IF you created the features correctly and in the right order to start with, and IF the part was not imported from another CAD system. These are two of the key reasons for having direct editing in the first place.

I tested this example on 6 other popular CAD systems. I was not impressed at all. With one very popular CAD system I could not even create the part - when I tried to add the chamfer it completely failed. So I could not even try the direct editing tests. Too bad, I thought CAD had progressed beyond that. I also noticed that on many of the systems I tested, the chamfer around the blend was very inaccurate and tangencies were not being maintained through the edits. Amazing!

The next level of “predictability” to review is when we start changing topology during a direct edit. For example; move one of the tapered side faces in to the point that it intersects the hole. In some CAD systems, the direct editing functionality won’t allow this type of edit. In others it may work but with some strange results. Then in others you may get what you expect. The technology is certainly improving rapidly.

Anyway, have fun with the example and please post your findings and results. Were the results predictable?

Paul

Editing 3D Geometry - Summary

2009-08-26T08:00:00.009-06:00

So what do the previous posts regarding direct and indirect editing mean to product design?

As history-based modeling has been the dominant technology for many years it gets used for a wide variety of design. As history-free modeling becomes more robust and useful we now have two very viable and very different technologies to choose from. As this choice impacts the data or “intellectual property” of your company and will impact your product development process, the choice should be based on something more than just user preference.

History-Based

With history-based technology, editing is typically indirect and the layer of intelligence used to drive the edit is created at the time the model is created. It’s all about creating a properly structured history tree. This environment naturally demands consistent modeling methodology and close attention to what and how the model may need to be changed in the future. The basic benefit of such an environment is that by appropriately recording every modeling step, anyone of the steps can be edited resulting in a different model. The basic challenge with this environment is that it requires consistency in modeling practices, can be very inflexible, can be difficult to learn and will require a good knowledge of the structure before utilizing the data. What you "see" is not what you get with history-based modeling. From a process point of view you need to make sure that the value you gain from a well structured history tree is worth the investment.

Direct editing will continue to be added to history-based modeling and will bring some added benefits, but as long as it is history-based it will be somewhat limited in capabilities.

If your process and products demand highly structured engineering data and this data will have a lifespan and utilization that will justify the investment, then history-based modeling may be a good fit.

History-Free

With history-free technology, editing is typically direct. There is by default no data in the model that would describe how the model was created or that would drive one feature to influence another (parent/child). With history-free modeling what you see is what you get. It provides a very fast and flexible modeling environment with no requirement to understand design intent before beginning the modeling process. The basic challenge with history-free technology is in the editing of complex shapes. While the technology is rapidly improving, editing a shape that consists of B-spline or NURB surfaces with lots of rounds and filets can sometimes be difficult. Again, it goes back to topology. Keeping these surfaces “connected” during stretches and moves is not trivial. These complex shapes can certainly be modified with history-free technology, but it’s not as simple as changing a parameter and replaying the history, (assuming the history will support the edit).

We will continue to see more indirect editing capabilities in history-free modeling. PTC CoCreate has been using the D-Cube DCM technology for many years to drive its indirect editing capabilities. LEDAS has also developed very similar technology and you can now see this technology working in Rhino.

From a process point of view, if you just need to get designs done as fast as possible with as much flexibility as possible, then history-free technology may be the best fit. It is also a very lean technology. There is simply much less data involved with history-free technology. Large assembly in-context design is a natural fit.

The above comments have more to do with the use-model of the tool. From a use-model point of view there are many differences and these differences will certainly impact the design process. Of even greater importance than use-model is “data”. While both history-based and history-free technologies create solid B-Rep models, there is significant difference in the actual data that is being created. This data is valuable intellectual property (IP). This IP carries with it the results of a significant investment in product development. It is at the core of your product development and may have a lifespan measured in decades.

With history-free technology the 3D B-Rep solid is the master document. Without it you have nothing. With history-based technology the B-Rep model is just a by-product of the history tree. The history tree is the master document. In the context of history-based modeling, without the history tree you have nothing - but a “dumb” solid. The biggest and most significant issue regarding maintaining a history tree as the master document is that a history tree is proprietary. There is no industry standard for exchanging this data. As such it is likely that much “history-based” engineering IP (the history tree) is going to have a “relatively” short lifespan. Pay close attention to the IP of product development, the investment you put into it, and how it may impact your future product development.

It is interesting that some CAD companies talk about combining history-based technology with history-free technology. It will be interesting to see what they come up with. Today CAD data is either history-based or it is not. Once history is gone, it is gone. Recreating a history tree from a history-free model will be similar to recreating a photo album that has been destroyed in a fire. History-free and history-based CAD systems can certainly coexist and complement each other, but it must be well understood how this environment, and IP, will be managed.

Now that these two choices exist and are both very capable, people should take a close look at their product development process and consider which technology best fits their current and future needs. There are many characteristics to consider.

Paul

Editing 3D Geometry - Direct Editing

2009-08-20T08:00:00.001-06:00

In the previous post I discussed the technology around "indirect" editing. With this post I hope to review some of the technology around "direct" editing.

Direct editing is now available in most history-based systems and is of course available in history-free systems (direct modeling). Direct editing requires no intelligence to be assigned or managed in the model. This technology provides the ability to interact directly with the 3D B-Rep geometry. In most cases any B-Rep solid model regardless of where or how it was created can be modified with direct editing capabilities. Directly manipulating a B-Rep model is however not trivial, but the technology has been developing over the last twenty years and is very mature.

Just a quick review. Boundary representation solid models (B-Rep's) are defined based on connectivity. Very simply put, points are connected with edges, edges are connected to form faces, and faces are connected to form "water-tight" solids. The way in which a model is "connected" is referred to as topology. If a direct edit forces a change to the topology, i.e. adding or removing faces, edges or points, a Boolean operation must be performed. In the case that the edit does not force a change to topology, a local operation can be used. As we attempt to drive a particular geometry change through a direct edit the system needs to be intelligent enough to know what function is going to provide the best and most “expected” result, reliably.

Unlike indirect editing, direct editing will require the user to "explicitly" define "what" will change (the geometry) and "how" it will change (the transformation).

Specifying the “What”. In the simplest form a user will simply click on a face to select it. This defines the “what”. If the modification involves more than one face, the CAD system may provide a multi-selection function so that many faces can be selected. Some systems also utilize real-time feature recognition to assist the user in selecting multiple faces that represent a boss, pocket, rib or slot. User defined features may also be available. There is also some emerging technology to help with the “what” that is based on conditional assumptions that the system can make for the user. Perhaps a planar face is selected; the system may make the assumption that all other co-planar faces should be selected. Or perhaps the system can make the assumption that all adjacent faces that are tangent should be selected, for example. There is enough intelligence in the basic B-Rep model for the system to recognize these types of conditions. With some advanced systems, geometry selection may be possible across multiple parts, thus maintaining relationships between parts during the edit.

Specifying the “How”. Now that we have defined what is going to change we need to specify how it will change, i.e. the “transformation”. This usually comes down to defining a 3D axis or a 3D direction vector along with a distance or angle. Many systems will provide some sort of 3D icon/tool to help define the transformation. With this type of tool the user will be able to select a direction vector or an axis and then drag the selected geometry some distance or angle to define the transformation.

The transformation tool in Solid Edge ST

The transformation tool in CoCreate Modeling

Once the direction or axis has been specified, the distance or angle must be specified. Different CAD systems have different capabilities for specifying this information as well. Certainly all will allow you to drag a distance or angle. Most will allow you to type in a number. Some may even allow you to reference other geometry. In some advanced systems this referenced geometry may be geometry in the model you are currently editing or may be geometry of another part in the assembly.

With the “what” and “how” specified, the modification can be completed. Geometry is immediately modified as the modification applies directly to the B-Rep solid model.

The benefit of this technology is that the user does not need to be concerned with how intelligence or parameters are defined or structured. They can simply manipulate the geometry regardless of where and how it was created.

Direct Editing; History-Based

This technology is fairly new to most CAD users. It provides the ability to interact directly with the "resulting" B-Rep of the model/history tree. Each direct edit must be captured in the tree as each time an indirect edit is made a new B-Rep is created, and all direct edits will need to be reapplied.

Don’t confuse the "Instant" or "Dynamic" or "Direct-Shape" editing of parameters with direct editing. These are "indirect" edits that dynamically and in real-time modify parameters that control features. This technology is certainly useful, but like any indirect edit, the results are subject to the pre-defined feature definition and order.

During a direct edit in a history-based system it is unlikely that the system will utilize any of the geometrical relationship found in the B-Rep topology as this may be changed by modifications to features that occur earlier in the model/history tree. As such most direct editing in a history-based system will be somewhat limited in several different ways. There may not be powerful selection methods such as multi-face selection or feature recognition, and selection across parts will most likely not be allowed. There may not be powerful tools for specifying transformations, and the system may not be able to handle complex topology changes.

Direct editing in a history-based system is also complicated by the fact that these edits must be captured and structured into the tree. In reality when you perform a direct edit in a history-based system you are adding a step in the tree. This step must be ordered and maintained as with any other element in the tree. As such the tree can get more complex. Direct edits can be impacted by parent features and will impact child features. In reality direct editing in a history-based system may result in more issues than value. As such it may be best to avoid direct editing in a history-based model until late in the model development. It is certainly nice however to have the capability when working with imported models.

Direct Editing; History-Free

If you use a direct modeling tool like CoCreate Modeling, KeyCreator or SpaceClaim, this is the environment that you are most familiar with. It is the default method of changing 3D geometry in a history-free direct modeling CAD system. In this case users interact directly with the B-Rep geometry. As there is no history tree, the edit is a one-time event and is not recorded in anyway.

As this is the primary method of manipulating geometry in history-free systems, it is important for there to be a variety of powerful tools and methods for selecting geometry. Tools and methods may include things like multi-select, box select, feature recognition, conditional selection, user defined features, patterns, selection lists/filters and so on. Selection across parts should be possible. Once the required geometry has been selected it is necessary to specify the transformation, and these systems should certainly have a variety of tools and methods for doing this as well. Multiple transformations in one operation may also be available. Intelligently interrogating the B-Rep and utilizing the information within is critical to the process of robust direct editing.

Of course after the selection and transformation has been defined, it is critical that the resulting modification be the expected one as there are often multiple solutions. Some examples of this are covered in an earlier post titled: "Getting Expected Results With Direct Editing".

Direct editing is certainly gaining momentum in our industry. It provides a giant leap in flexibility over indirect editing, especially history-based indirect editing. With some of the advanced selection methods that are now available in a few of the history-free systems, direct editing can even maintain relationships between parts and assemblies - something typically only done through indirect editing.

In the next and last post on this topic I will try to give some summary statements on what all of this can mean to product development, (although that is really up to you to determine).

Paul

Editing 3D Geometry – Indirect Editing

2009-08-17T08:00:00.008-06:00

Indirect editing is typically used in parametric modeling, or history-based systems. With indirect editing, parameters, dimensions and other intelligence is associated to the 3D model and can be used to define possible transformations and relationships. In a history-based system this intelligence is captured in the history-tree at the time the model is being created. In contrast, with a history-free system the intelligence is captured in the B-Rep model, during or after model creation. In either case (history-based or history-free) this intelligence can be used to specify geometry transformations. The added intelligence describes “what” will change, i.e. the geometry, and “how” it will change, i.e. the transformation.

By modifying and processing this intelligence, the resulting 3D geometry will be different. What geometry is actually changed is completely dependent on how the intelligence is setup and structured. It is “indirect transformation” of 3D geometry.

The benefit of this technology (indirect editing) is that you can capture and/or assign a specific behavior to the model. In a situation where you can predict or anticipate future changes this technology can be very useful. It is also useful if it is important to tightly control relationships between faces, features and parts during edits.

Indirect Editing; History-Based

This is the environment that most 3D CAD users are familiar with. It is the standard method of changing 3D geometry in a history-based CAD system. Parameters at the 3D level are managed within the history tree and are structured in a parent/child relationship. Structure, relationships and parameters are always being created and ordered in the tree as the model is being developed. The process of properly organizing and managing this structure is not optional. It is something that every history-based CAD user must learn to be profecient with the tool . With history-based modeling you are either adding structure or modifying structure (indirect editing). When changes are made to the history (sketches, parameters, features, order) the tree/model is regenerated and is solved linearly based on the structure of the tree.

In this case it is important to know what the structure is and how a change will impact any child features. As it is linear there will be a “ripple” effect with this technology and as such it is important to know the structure before getting too aggressive with changes. In many cases the ripple effect is desired and equally in many cases it is not.

History tree in Pro/ENGINEER – ordered and structured

With history-based modeling users are actually editing the process and structure, or “recipe” that was defined at the time the model was created. You do not actually modify 3D geometry, but rather modify the recipe and then let the system rebuild the 3D geometry based on the modified recipe. In this context 3D geometry is always being recreated from the recipe rather than being modified.

As with any indirect editing capabilities, it is certainly possible to drive a change that can invalidate the model. Knowing how to work through these issues is critical to good history-based modeling.

This technology has recently been getting a bit of a facelift with what is called “dynamic” or “Instant” modification. With this capability a user can directly select a face or feature of a history-based model and dynamically modify the intelligence (parameters, dimensions) associated with the selected geometry. The intelligence is still solved linearly, but processing is more real time, or “instant”. It looks something like direct editing, but it is still indirect and as with any indirect edit, the results are completely dependant on the structure of the intelligence.

Indirect Editing; History-Free

This technology is not new but it is foreign to most CAD users. It provides the ability to indirectly manipulate 3D B-Rep geometry through added intelligence (parameters, dimensions) similar to indirect history-based modeling. However in this case parameters are not captured in a tree structure, but are rather captured, or “tagged” directly to the elements of the B-Rep model, i.e. points, edges or faces. Rather than being solved linearly these relationships are solved synchronously, or “nonlinear”. The order in which the parameters are assigned has no influence. With this technology there is no ripple effect based on a parent/child relationship, however one relationship can certainly drive another if desired.

Relations Browser in CoCreate Modeling – no order

With history-free indirect editing 3D geometry is actually being modified rather than being recreated as is the case in history-based modeling. There are several different technologies that can be used to modify B-Rep solid models. When modifications of a B-Rep are driven indirectly, the resulting transformation must not invalidate the B-Rep solid model. As we attempt to drive a particular geometry change through an indirect edit the system needs to be intelligent enough to provide the “expected” result, reliably.

As is the case with indirect history-based editing, changing a parameter will result in some change to the geometry. Knowing how the parameters are structured is important in order to make good use of the intelligence and achieve the desired results. As it is not order dependant (linear) it is relatively easy to manipulate this intelligence.

Today there are not many history-free CAD systems that provide this capability. PTC CoCreate Modeling is one of the few that does provide it. Here is an example of history-free indirect editing in CoCreate Modeling that I posted in a previous article:"Design Intent with History Free Modeling"

There are pros and cons to each; history-free indirect editing and history-based indirect editing. Understanding which one can best support your requirements can be a challenge, but will be worth the analysis.

In the next post we will review Direct Editing.

Paul

Editing 3D Geometry (Introduction)

2009-08-13T08:00:00.003-06:00

While history-based systems are learning how to interact directly with geometry and are becoming more “explicit”, history-free systems are learning how to drive geometry indirectly, or “parametrically”.

So what’s involved with editing 3D geometry? When we use a 3D CAD tool for design purposes we are basically describing and transforming 3D geometry in a virtual environment. Today this process is done “directly” or “indirectly”. Indirect describes the typical methods where structure and intelligence is defined and later modified to drive 3D geometry. Direct describes the “explicit” methods of interacting directly with 3D geometry. Interestingly enough, today both of these interaction models exist whether the 3D CAD system is history-based or history-free.

This article turned out a bit long so I’m going to break it up into a few parts. With these posts I want to specifically review the details of how 3D geometry is edited and modified in a 3D CAD system. I think that as we CAD users learn more about what is going on in our CAD systems and why, it can make us better users. I hope this discussion will help.

In the next two posts I will discuss these two technologies in detail. We will first take a look at how “indirect” editing works in the history-based environment and how it works in the history-free environment. Then we will take a look at how “direct” editing works in each of these two environments.

Watch for the following two posts in the near future. You can click on the follow-me link on the right side to be informed when they are posted.

Editing 3D Geometry – Indirect

With indirect editing, parameters, dimensions and other intelligence is added to the model that will define possible transformations and relationships. In a history-based system this intelligence is captured in the history-tree at the time the model is being created. With a history-free system the intelligence is captured in the B-Rep model during or after model creation. In either case this intelligence can be used for maintaining geometric relationships and for specifying geometry transformations.

Indirect Editing; History-Based
Indirect Editing; History-Free

Editing 3D Geometry – Direct

Direct editing requires no intelligence to be assigned or managed. This technology provides the ability to interact directly with the 3D B-Rep geometry. Directly manipulating a B-Rep model is not trivial but we are getting much smarter at it. As the edit is being done directly, geometry must be selected to edit and transformations must be explicitly defined.

Direct Editing; History-Based
Direct Editing; History-Free

At the end of these posts I will provide a quick summary and review of how these technologies can impact your product development process. Hopefully you will have a better idea of where these technologies can provide value.

Paul

Part 2 = Editing 3D Geometry - Indirect Editing

Part 3 = Editing 3D Geometry - Direct Editing

Part 4 = Editing 3D Geometry - Summary

Direct Modeling - Thinking Outside the Box

2009-07-20T07:26:00.000-06:00

Most CAD users are very familiar with history-based parametric modeling. It is likely what they learned in school and actually may be the only 3D CAD technology they have ever used. As a matter of fact, most do not know that there is even an alternative. When the topic of 3D CAD comes up, it is almost always in the context of parametric history-based modeling. “3D CAD” IS parametric history-based modeling for most people.

There is now certainly more attention being given to history-free, direct modeling and as such, many people are now experiencing it for the first time. This first exposure can be a good experience or a bad experience depending on many different factors. Here are a few things to consider before getting too frustrated with it and putting it back on the shelf.

Creating models without a history tree is fundamentally different than creating models through a history tree. And don’t confuse direct modeling with direct editing. Direct editing is available in either technology and as such many CAD users may be familiar with the concepts. Direct, history-free modeling is much more than direct editing. To take full advantage of history-free modeling, it will require that you think outside the familiar history-based box.

For most 3D CAD users the common reaction to history-free direct modeling is that it seems to be too freeform and “unstructured.” A history-based CAD system, to a certain extent, guides the user through a structured modeling process. Many have developed modeling standards and best practices to ensure consistency in the process. A properly structured modeling process may yield a properly structured model. With a properly structured model, flexibility AND inflexibility can be provided where necessary. The investment in learning how to use the structured modeling process to get a structured model that works as intended can be rather high. For those that have made this investment, it may be difficult to accept this “unstructured” history-free environment.

Structured Modeling

For some, when stating that history-free modeling is “too unstructured” they are in fact referring to the modeling process. They find value in a system that, to some extent, guides or imposes a particular modeling process. They find it helpful in that there is only a few ways to get a particular result. Again, the process is guided and structured. They gain some sense of “safety” in this environment. With history-free modeling there is no concept of a structured modeling process. There is complete flexibility in how the model is created and edited. This “unstructured” modeling process may be considered too “unsafe” for them. Perhaps this “unsafe” environment might allow them to do something to the model that they should not do. However, it must be considered that a structured modeling process certainly does not guarantee “safety”. Recreating history-based models is all too common.

Structured Models

Closely related to the “structured modeling process” is the “structured model”. For others, “structured” refers to the structured model, a model that is embedded with design intent to the point that it closely represents the physical. The concept of the structured model (design intent) came into existence with the introduction of history-based modeling. “Capturing design intent” was the justification used for the high investment required in the structured modeling process of history-based CAD. Many have come to accept that a structured modeling process is the only way to develop well structured models and to yield models that behave as intended. In the early years of direct history-free modeling, embedding structure and intelligence into the model was not possible, so there is certainly some validity to these notions. Several history-free systems today still do not provide the capability to add structure and intelligence to the model. PTC CoCreate Modeling is one of the few that does provide a good set of tools for adding structure. Structured history-free models are a reality, but the process of adding this intelligence is not as inherent with the modeling process as it is with history-based CAD. With a history-free tool like CoCreate, you can add structure to the model anytime in the process, even after the model is fully developed and refined or even to an IGES or STEP model. With history-based CAD, the development of model structure starts the moment you begin the process of modeling – and it is not optional.

So if you are one that is concerned about an unstructured modeling process, be sure that you clearly understand the value of the structured process and its support of your design process. Be sure that the significant investment in this structured process provides real value. In many cases it does not, and that is why many have added direct, history-free modeling to their toolset. Mistakes can be made in both technologies and in either case your work must be validated. This validation can happen real-time with or without a structured modeling process.

If you are one that is concerned about the structured model, you actually have two choices now. Both technologies can provide similar results, but the means to the end is very different. In a situation where every part model needs to be well structured and changes are predictable and controlled, history-based modeling may be a good choice. In a situation where it is more important to get quick results, and the investment into the structured model is only needed occasionally, your best choice may be direct, history-free CAD.

Initial reactions to direct history-free modeling are usually based on a few key factors:

Previous CAD experience and individual productivity will certainly impact your initial reaction. However, these should not be significant factors when determining the viability of the technology. (Unless you work by yourself, and the resulting CAD data has no lifespan or future value.)
The type of work you do, including your process requirements, will also have a big impact on your initial reactions. Process and process requirements should always be key criteria in the analysis of technology.
The capabilities of the direct modeling tool may also have an impact on your initial reaction. There are many new and very immature examples of direct modeling out there. In some cases they are very poor representations of what direct modeling can and should be. Be sure to look at a few before making any final judgment.

Be careful in weighing your criteria (reactions) as you experience this new world of “explicit” “history-free” “direct” modeling. Take a step outside your comfort box, keep an open mind and focus on your product development process requirements.

Paul

Inventor Fusion: “Unites direct and parametric workflows” - What?

2009-06-25T05:00:00.000-06:00

The Inventor Fusion preview is now available. I am anxious to see this thing. Inventor Fusion “Unites direct and parametric workflows”. This is one of the title statements found on the Autodesk Labs web site. I hate to burst the bubble but “direct” and “parametric” workflows have already been “United”. It first happened about 10 years ago when Hewlett Packard embedded the D-Cubed 3D DCM parametric solver into their SolidDesigner (Now PTC CoCreate) product. Siemens has followed by using the same D-Cubed solver inside their Synchronous Technology. There are certainly differences in how these technologies are “united” and implemented in these systems, but the “unite” has already happened.

The first bullet under this title goes something like this: “With the introduction of Inventor Fusion technology, both direct, history-free and parametric, history-based workflows are united”. There could be some confusion in the usage of terms here, but again direct and parametric technologies have already been united. This statement however takes it a bit farther. It claims that history-based and history-free have also been united. If they are referring to a synchronous uniting of this technology, they are wrong. Either a system is recording the modeling steps, or it is not. It is a “1” or a “0”. And if it didn’t record it … assumptions must be made if a record is to be created after the fact.

It goes on to say, however that “Changes can update into the model's parametric feature history, ensuring critical design intent is maintained”. Now this could be cool, but I’m not sure. Are they simply referring to capturing the direct edit into the history tree, as any other (including Inventor) history-based system does with direct edits (nothing new)? -OR- Could they be referring to creating or modifying sketches, features, parameters, and structure of a history tree based on the B-Rep geometry of a history-free model? This however would be nothing new as well. Many companies, universities and creative individuals have been working for many years on this type of technology. It involves analyzing unintelligent 3D B-Rep geometry in an attempt to recognize characteristics in the model such that a fully functional history tree can be created (or perhaps edited) including sketches, features, parameters and structure/relationships. If successful the resulting history-based model could be edited using the standard history-based editing techniques. The system must make many assumptions to do it. Autodesk has been working on it with their Feature Finder, maybe they have made some major breakthroughs. SolidWorks has been working on it with their FeatureWorks technology. PTC has similar technology in their Feature Recognition Tool (FRT). All of this technology attempts to make sense/intelligence of a non-intelligent B-Rep model – the kind that comes from direct modeling. None of it works very well.

There could be another option I guess. Perhaps Inventor Fusion is tagging the B-Rep history-free model with information about a specific direct edit such that the information can be accessed back in the history-based environment to drive identical changes to the history-based model through the manipulation of a sketch, parameter or structure. This could be real messy in many ways, and would only work if the history tree is structured in such a way that the edit would actually work and not attempt to invalidate the model. It would also mean that inventor Fusion would be an "editing" tool only, not a modeling tool.

And then it is interesting to consider how you would rationalize having a history-based model and a history-free model of the same part. Which one is the master document? How would the PDM system handle it?

In a history-free system the 3D model is the master. In a history-based system the history-tree is the master and the 3D model is just a result. Two very fundamentally different technologies.

Well, speculation is fun but I wonder if Autodesk would let me download the Inventor Fusion Preview. Since they have a link to my blog on the inventorfusion.com site, I think they should. We’ll see. I do like some of the interaction and use model I see in the videos, but I am most interested in the round trip between history-free and history-based, if such a thing exists. As you can tell, I am a bit skeptical.

Paul

Some Random Observations of Product Development

2009-06-18T08:30:00.000-06:00

While I certainly enjoy a good discussion and review of technology, especially the technology of 3D CAD, I equally enjoy a good discussing and review of the process of product development. As I have mentioned in previous posts, I have had the opportunity to visit many companies over the years specifically to review their product development process (PDP) and to consider what and how improvements can be made. Over the last 12 months I have had the privilege of doing process assessments with about 15 different companies. I know this is a small drop in a very large bucket, but it's been interesting.

The companies range from small 2 or 3 facility companies to huge global companies. Industries represented include high tech, machinery, medical, bio-sciences, military, oil & gas, and transportation. Product lifecycles range from 6 months to 50 plus years. Annual product volumes range from one to millions. Throughout these companies there is a vast array of different tools and technologies used to support the process.

Here are some of my random observations:

A PLM system does not necessarily reduce the need for individual discipline

Duplication of effort is much too common in product development

2D drawings are by far the preferred method of conveying definition and design intent

Habits, culture and the path of least resistance often take precedence over process

Much data is created in the PDP that adds no value beyond the individual

Engineers doing more data entry and project management

Individual productivity does not equate to team productivity

Tools and technologies are often chosen based on personal preference over process

Still a lot of shared drives out there

IT often has significant influence, but equally often has little PDP knowledge

Throw-it-over-the-wall is still all too common

Much regulatory compliance is still paper based, (so they think)

ISO Certification is a book on the shelf

Regardless of value change may not happen

Regardless of value change may happen

Knowing how to use a wrench doesn't make you a good mechanic

Not knowing how to use a wrench is a problem

"PLM? I just need to get my job done"

Some of those appear to be more negative. Here are some that are more positive.

People genuinely want to do what’s right. Engineers are top-notch people

Engineers are also very creative, (this isn’t always good)

The vision for product development is relatively consistent and progressive

Innovation happens and tools don't get the credit

There is a huge culture gap between the senior and the youth, (good as long as youth knows where help comes from, and senior is open minded)

Having a full toolbox is a good thing when problems need solved

Collaboration with outside suppliers and venders is improving

3D is making its way into all aspects of product development

From drawing boards in open spaces and real-time collaboration - to - CAD in scatterd cubicles and... Twitter??

I started adding examples for each but it got a bit crazy so I will just leave it at this for now. You're welcome to add some of your own random observations.

Paul

PTC User 09 and CoCreate - Day 3

2009-06-10T15:30:00.000-06:00

I started out the day with an early round of golf (I wish I knew how to play golf). Fortunately I had to leave after about 13 holes to get back to one of the CoCreate training sessions.

The fact that I played golf, means that I missed the KTM keynote. I would like to have been there.

I arrived at the class a bit late, but Brad Tallis (PTC CoCreate Technical Consultant) was doing a nice job of leading and teaching the class. The class was full. All students were Pro/ENGINEER users just trying to get more familiar with what CoCreate Modeling is. It can be a bit difficult to get out of the mindset of structuring a history tree, but the lights come on fairly quickly. We had a great time and it appeared that the students all had a great time as well. They all wanted more but the time was over all too soon. We encouraged them to download the free Personal Edition from ptc.com and try it out some more.

PTC User was a great experience this year. It was my second one and I enjoyed meeting more of the PTC community. I also enjoyed meeting in person some of my fellow bloggers and others that I have virtually met in the social network.

I hope these blog posts were of some use to those of you that could not make it to this years event, but I more hope that we will see you at next years event.

Boarding now, got to go.

Paul

PTC User 09 and CoCreate – Day 2

2009-06-10T04:00:00.000-06:00

John Abele from Boston Scientific was the keynote speaker for today. What a great story. He is a pioneer in many ways. Some of the statements that caught my attention included the following. “Pioneers have arrows in their back”, somewhat referring to the fact that innovation and progress is not without many trials. “Change agents don’t come from the establishments”, another interesting comment that can apply in many different ways. Another one I liked; “preparing to be lucky”, think about that for a minute. He also made some good statements about customers becoming family, salespeople, application developers, engineers, presenters and strategists – basically user groups.

John also told a most fascinating story about finding the submarine that his farther served and died on during WWII. I can’t begin to describe the story, so if you missed it, you just missed it. It was amazing.

I then participated in a meeting with PTC User representatives and other CoCreate users interested in trying to find ways to build up the CoCreate user community. One of the better ideas that came from this discussion was to encourage regional user group meetings. We are looking for a few customers that will step up and be willing to host such an event. I can tell you that if you do you will be well supported. These can be great events and platforms for some valuable collaboration between PTC User, PTC and our customers.

In the afternoon Brad Tallis taught a class on CoCreate Modeling advanced topics. We had several CoCreate users attend the class and even a few brave Pro/E users. He showed many productivity tips and tricks that are perhaps not so well known. There was even some other sharing from some of the attendees with their own tips and tricks. Brad went into some details on part and assembly structure management and then showed how this structure and organizing can be utilized in modeling operations as the design progresses. As CoCreate Modeling has no part modeling mode or assembly modeling mode, you can leverage this virtual 3D environment in some very useful ways. He also went into many other details about sectioning, clip planes, advanced blending capabilities, 3D curves and surfaces capabilities. He ended the class by showing many different ways to take advantage of Configurations to capture states, positions, exploded views, view settings and so on.

Brad and I both were doing demos of CoCreate Modeling in the exhibit hall. It is always enjoyable seeing the reaction of people when they start to realize and understand what CoCreate Modeling is. Several people kept coming back for more. I don’t think they believed it the first time.

Paul

PTC User 09 and CoCreate – Day 1

2009-06-09T05:00:00.000-06:00

The day started out with a talk from Jim Heppelmann and Brian Shepherd. Technology just keeps moving forward. What might be interesting to some of the CoCreate folks is the appearance of some CoCreate technology inside a future version of Wildfire. A brief video was shown of the concepts with stronger direct editing capabilities within Wildfire. Could be interesting.

The CoCreate specific content started with a presentation from Dan Gioia from Gioia Consulting. His presentation was focused on the design of electro-mechanical assemblies using IDF and CoCreate Modeling. By sharing data between the EE and ME disciplines he is able to show a considerable reduction in late changes and errors as well as eliminating the confusion of multiple layout passes. Just for reference, the IDF exchange capability is part of the base CoCreate Modeling product.

Andy Poulsen from Aspiration Innovation, Inc. was up next. Andy is a master at creating productivity add-ons for CoCreate Modeling. He showed us some great examples of the power of the CoCreate Modeling Integration Kit, which is a LISP based customization layer that can be used for creating your own custom tools and automation routines. You should checkout: http://www.asp-inno.com/ for more information about the products and services they provide.

During lunch I spent some time at the CoCreate booth. Many people came by to better understand what the heck CoCreate Modeling is. No one left unimpressed. It’s a blast showing off this product.

In the afternoon Martin Nuemueller, Product Manager for the CoCreate products presented the CoCreate product roadmap. Martin presented many of the breakthrough technologies around explicit modeling that are coming with v17. I’ve had the opportunity to use early v17 and can tell you that “breakthrough technologies” is a great way to describe it. The focus is around improving speed, flexibility, predictability and intuitiveness. I guess Software companies are always working on these things, but the CoCreate team is taking some big steps with v17. V17 also includes much more interoperability with many of the other PTC products. These integrations can greatly increase the value you can get out of your 3D engineering data coming from CoCreate Modeling.

There is also new stuff coming in Model Manager as well such as management of inseparable assemblies, PCB integration, management of stock-finish parts (multi-opp parts), advanced version control and many more. Martin also talked about the coming gateway between Model Manager and Windchill.

Berthold Hug (PTC Prod Mgr, CoCreate Modeling) and I then presented the “Explicit Modeling Outlook”. I talked briefly about the technologies of parametric modeling (history-based) and explicit modeling (history-free). How these two technologies can address different needs and requirements of product development, but also how they can overlap and complement each other. The most exciting part was Berthold’s presentation and the demonstrations of v17. Wow!! I am hoping that I can get some images and videos posted real soon.

Korie Carter and Scott O’Brien of Tensor Engineering also presented how they are using CoCreate products in steel bridge detailing. They showed several pictures of very large and very complex bridges that they have worked on in the past, from locations all around the county – check out their web site at http://www.tensorengr.com/ There is basically no room for error in a business like this. You don’t get to create any prototypes, the volume of product is 1, and the cost of the product is… well, I have no idea. It is very interesting to see how a company like this is using 3D modeling to minimize the opportunity for error and help solve design problems. It’s not that they are not able to do it with 2D, 2D CAD is still a very important part of their process. It’s just that in many cases 3D can be used to more effectively visualize and solve geometry problems. They also use it to visualize the construction process. They even animated the assembly process to capture the specific sequence of assembly. In many cases it is critical to ensure that pieces are assembled in a very specific sequence. These animations make it very clear. Nice job Korie and Scott!

To end the day, Brad Tallis, a Senior Technical Consultant at PTC, gave a presentation and demonstrations about virtual prototyping using some of the advanced capabilities of CoCreate Modeling. He showed simulation and animation of mechanisms to identify any potential interference or conflicts. This capability will work with any geometry from any CAD system. He then showed the integrated FEA capabilities within CoCreate Modeling. He was able to identify areas of weakness, quickly change the model in many different ways to reduce stress and then rerun the analysis, all without being concerned with how the model was created in the first place - just quickly solving problems. Also in the context of virtual prototyping Brad showed the new cabling capabilities of CoCreate Modeling. He loaded an E-CAD file that defined the cables and their pin assignments. Using this data, CoCreate Modeling was able to create the cables and route them automatically and appropriately. Last, but not least Brad talked about taking advantage of the high quality rendering capabilities to use your 3D data to better understand what the product will actually look like. Bringing all of these capabilities together can greatly reduce the dependence on the physical prototype. And when it is time for a physical prototype you can be much closer to a final solution with less iteration.

So that was day one from a CoCreate perspective. Now on to day two.

Paul

Some Serious CAD "Geekery"

2009-06-08T10:00:00.000-06:00

For those of you that have not already done so, you should check out the geeky discussion going on a Matt Lombard's blog at:
www.dezignstuff.com

Not sure if any of that discussion helps clear the mud, but I hope so. Let me know what you think. It seems that it will only get more confusing as history-based technology adds more powerful direct editing and dynamic feature manipulation, and as direct history-free modeling adds more intelligence to the B-Rep.

The Big question is; what does it all mean to the process of designing products? It will certainly be interesting to watch.

Paul

PTC World User Event and CoCreate

2009-06-04T14:56:00.000-06:00

The PTC World Event is starting next week in Orlando. I am making last minute preparations for my trip and participation at the conference. Myself and several others will be there to represent the PTC CoCreate products. We have several presentations planned along with some free training. We also have a booth in the exhibit hall. We actually get to show off so very cool new stuff so it should be fun.

If you are planning to be there, please come by one of the presentations, training classes or the booth. I would love to meet some of the people that read my blog.

If you are not going to be able to make it, myself and many others will be blogging and tweeting real time as best we can to keep you up to date on what's happening. Watch for the feeds at:

http://www.ptc.com/events/ptcuser09/

Paul

PDM and the History Tree

2009-06-03T08:30:00.000-06:00

As you would expect, I take whatever opportunity comes alone, with whoever is willing to listen, to explain the benefits of history-free CAD. As such I get to hear many reasons why history-free CAD will not meet a person’s particular requirements. Some of these reasons are certainly valid based on their product characteristics and/or design process. Some, on the other hand, are, well, puzzling to say the least. It is amazing what some people believe that the history tree is doing for them.

One of the frequent and more “puzzling” reasons that I hear for needing the history tree is; “I don’t want anyone to be able to change my model”.

Wow! There are so many things wrong with this statement I’m not sure where to begin.

First of all, the history tree technology (CSG) was originally leveraged into 3D mechanical CAD to make the editing of models easier and more predictable, as compared to the ridged editing capabilities of the old B-Rep CAD systems. When did it become a method for restricting edits? It is true though, you can organize the history tree and constraints to make only specific edits possible. But then if you actually have access rights to make these very specific edits, you also have the rights to reorder the tree, or even corrupt the tree? Strangely enough, you most likely also have the rights to delete the file. Whether intentional or by accident, the model can be changed. Since when did the history tree become some form of data management?

Maybe these people are simply referring to the use of the history tree to capture and somehow communicate their design intent. If this is the case, we should consider how many people within the team and throughout the enterprise need to understand this design intent. And of those, how many have the skill to properly evaluate a history tree to accurately assess the intent. Of these people, how many should have access to the native CAD data? I think the number will get real small, real quick. We have been capturing and conveying design intent via 2D drawings ever since humans have been inventing stuff, and 2D drawings will continue to be the preferred method for many years to come. Model Based Definition may catch on at some point, but MBD does not require a history tree. What unique design intent is captured in the tree? And how does it get communicated to the greater enterprise?

I suppose that there are some that would tell me that what these people really mean is that they want to make sure that IF the model is changed, i.e. a boss is moved on one part, the mating feature on another part is updated accordingly. If that is the case, they are confusing the history tree with parameters and constraints. And please don’t assume that just because these relationships exist, you don’t need to check the results. Relationships and parameters can be changed, removed and even broken - and now we are back to data management.

Maybe I am missing something here, but it seems to me that there is a tendency to believe that a nice looking, well constrained 3D CAD model with a well structured history tree somehow implies “security” and “completeness”. Bottom line: if you think the history tree is somehow protecting your model/assembly, or perhaps somehow controlling and communicating intent, you’re at risk, (in so many ways).

Paul

Direct Editing in History-Based CAD

2009-05-28T09:40:00.000-06:00

In a recent post by Deelip Menezes titled “Direct Editing and Direct Modeling” Deelip brings up the fact that within the context of history-based modeling, this term can refer to two different things. He notes that in a typical history-based system like Alibre, a direct edit to geometry will result in a new “Move Face” feature that will be added and ordered into the tree. He then notes that in SolidWorks using the Instant3D functionality, the edit is not recorded into the tree. The two technologies referred to here are very different as I will explain below. Unfortunately they are both often referred to as “Direct Editing”. You can access his article by clicking on the link to his blog under “My Blog List”.

As I mentioned above, in the context of history-based modeling, the term “direct editing” is used to describe two completely different things:

1) Some history-based CAD systems (almost all of them now) have at least one or two functions that will allow a user to directly manipulate geometry – at the geometry level. When this manipulation is done within a history-based model the system must track the edit in the tree otherwise the next time the model is regenerated, the edit will be lost. This type of editing is great for parts in which the history tree has become unmanageable or overly complex and you just need to make a quick change, or when you are working with imported geometry. Direct manipulation of a B-Rep solid is not a trivial thing and many of these history-based systems don’t have the capabilities to solve complex topology problems. As such much of this capability can be very limited. This technology is the heart and soul of history-free direct-modeling CAD. A history-free CAD tool must be very good at solving topology problems, whereas a history-based system relies more on the tree.

2) Some history-based CAD systems provide the capability of dynamically manipulating parameters. Such is the case with SolidWorks and their Instant3D capability. This edit graphically appears to be a direct edit as defined in #1 above. In reality it is very different. There is no new “move” feature added to the tree, only existing parameters that are being dynamically edited. This method simply provides instant feedback of the parameter edit rather than waiting for a model regeneration. It requires that a parameter exist in the model. As such it may not always work, based on how the model was created in the first place, and as with any history-based edit it can impact child features. It also may not work for imported data. This is not new technology. IronCAD has been using it ever since it came into existence many years ago. We will certainly see much more of this technology in history-based CAD. Just to be clear, in history-free direct-modeling, you can also dynamically manipulate parameters, it’s just that the parameters are not history-based.

As I have mentioned before, there are really only two fundamental technologies used in mechanical “solid modeling” CAD today; 1=history-based (CSG+B-Rep hybrid) or 2=history-free (B-Rep). Direct geometry editing and dynamic parameter editing (or whatever we want to call it) can be available in both. It’s just a matter of how the geometry is managed; with history or without. They both have their pros and cons and each can greatly impact the design process.

Paul

A Fun Project

2009-05-27T07:30:00.000-06:00

My wife says I have way too many hobbies. She’s wrong of course. One of the “few” hobbies that I enjoy is building and flying RC airplanes. I am now flying the so called “giant scale” airplanes. My most recent airplane is a 1/3 scale model of an Extra 330 aerobatic airplane. The wing span is 102” and it is powered with a two cylinder 100cc 2 stroke engine.

Prior to the 100cc plane I was flying a 50cc Extra300.

A while back I had the unfortunate experience of disassembling this plane during a fairly hard landing. The landing really wasn’t all that hard, it was just that in the months leading up to this incident I had been making good progress in removing much weight from the airframe in trying to improve its performance. Unfortunately my weight reduction efforts eventually led to some compromises in the integrity of the airframe to the point that… well you know.

I could have purchased a replacement fuselage and had the plane flying again, but I decided to see if I could rebuild it. A friend had the same fuselage that I could use to measure parts, another offered to make the parts for me on his CNC router, so I decided to give it a try.

I spent a few hours measuring parts and sketching them out on paper. I then modeled all of the parts in 3D using CoCreate. As the assembly came together I adjusted the models as needed to get a good fit.

With the 3D models created and fit together, the necessary data was sent to the router to get the parts manufactured.

These parts fit together so well that they actually held together without glue. After spending some time cleaning up the old fuselage, the new assembly was fitted into what was left of the originally fuselage. With some glue and clamps the fuselage was as good as new.

The plane is now in great flying condition and I still enjoy flying it. I think I will just leave the weight alone this time. It is safe to say that had I used my 2D sketches and 2D drawings to manufacture the parts I would have had to correct a few mistakes and even make some of the parts over. With 3D models the parts were perfect, the first time.

Paul

Model Based Definition (MBD) – What’s the Hold-Up?

2009-05-18T08:30:00.000-06:00

Recently I have been talking with several companies about the possibility of reducing their dependency on fully detailed drawings. In a recent post titled “The Maturity Curve of Product Development” I used the following chart to show the different stages that companies go through as they learn to leverage their electronic CAD data deeper and broader into the product development process.

Model Based Definition (MBD) is a term used to describe the addition of information to the 3D model such that the model can represent the complete definition of parts and assemblies. For most companies, this complete definition is usually developed and managed in the 2D drawing and other related documents. At its fullest extent, model based definition can make it possible to reduce and even eliminate the need for 2D drawings.

Recently, Matt Lombard at Dezignstuff.com asked if any of his readers were using the 3D CAD Standards that are laid out in the ASME Y14.41 standard. This standard basically defines how 3D models are to be documented and annotated to fully represent the complete definition. So far he has not received too many responses, and no response that indicates the use of this standard and MBD.

Much time goes into creating fully detailed drawings. They can be expensive to create and manage. They can be easily misinterpreted. If developed from a 3D model, there is much duplication of effort. With duplication of effort comes a higher potential for error. Drawings can quickly become detached or unrelated to the 3D model. Once printed, they can become even more detached from the 3D model, and the opportunity for error increases. So, what’s the holdup?

Example from ASME Y14.41

Same part annotated in CoCreate Modeling

I have read a few success stories about MBD, but I have yet to witness one. As engineers at Hewlett Packard, we were successful with reduced content drawings, but we never made it to a “drawing-less”, or MBD process. There have been many claims to successful MBD in aerospace, automotive, and high tech electronics. I have visited many of these companies and am still looking for some good examples. I have seen some small examples from some progressive individuals or even small groups that have been able to push forward with MBD to some extent, but nothing that encompasses the complete product lifecycle. Maybe I just haven’t visited the right places.

What does it take to move to a model based definition? The technology exists. Most all modern 3D CAD tools have some capability for MBD. Some are better than others. Several free viewers are also available to read and view these annotated parts and assemblies. I would love to hear from some of the readers. What are the challenges you would face, or are facing?

Same part viewed in eDrawings

Same part viewed in 3D PDF

As I stated in the post regarding the maturity curve, making the move up the curve will be an evolutionary move – one step at a time. First, you need to understand where, when and why part and assembly definitions exist in printed form. I see a significant use of computers on the shop floor, in manufacturing and assembly. It’s even becoming common to see 3D representations of parts and assemblies on the monitors. But it’s equally common to see a printed 2D drawing lying on the workbench next to the monitor.

As we continue to move to 3D based product design and manufacturing, the development and management of drawings will become a duplication of resources and effort, effort that we may not be able to afford much longer.

Here are some challenges to MBD that people have shared with me.

The culture chasm, it’s a giant leap
Quality management/inspection
Compliance with industry specific regulations
Our suppliers, partners
Cost & disruption vs. value
Inadequate tools/technology

I recently needed to make a part on the lathe in my garage that I first designed in 3D. I didn’t take my laptop with me; I took a printed drawing – hum…

Paul

Design Intent with History Free Modeling (another example)

2009-04-30T11:00:00.000-06:00

As I have mentioned many times, combining parametric modeling capabilities with history free modeling to capture design intent is nothing new, as some CAD companies would indicate. There is certainly always room for improvement in how it is presented to the user, but the basic technology is fairly mature and robust. The term “parametric modeling” usually refers to capabilities in a CAD system that will allow users to get 3D geometry to behave as intended based on the design requirements, and this is typically done by capturing the steps (sketches, features, parameters) of the modeling process, i.e. the history tree. Many people understand the term “history-free” (or “direct” or “explicit”) then to imply that the capture of design intent is not possible. As this example will show, it is certainly possible and also can be easy to do.

In this example I am using PTC CoCreate Modeling to add intelligence to a non-intelligent assembly of a V8 crank assembly. You have probably seen examples like this many times, but I bet you have not seen one without a history tree.

In this case much of the geometry comes from a different CAD system through the STEP format. As you will see in the demo video, I add relationships (parameters/constraints) to control the assembly; how the parts relate to each other. I also add relationships to control the geometry of the crankshaft and other parts based on the stroke of the engine. It’s been a fun example as my son and I have recently finished building the engine for the Camero that we are restoring. In our case we took the stock 350 engine and stroked it to a 383. This is done by putting a 400 crank into a 350 block. When you do this, you have to use shorter rods and/or different pistons to accommodate the longer stroke. In this example I change the length of the rod based on the stroke.

As you may have noticed the change to the rod is somewhat simple from a geometry point-of-view. No topology change is required, only repositioning of some faces and stretching of others. The changes to the crank, on the other hand, are a bit more complex. There is still no topology changes required, but there are several tangencies, coincidences and blends/rounds that have to be maintained.

Direct history-free modeling systems may provide the capability to add (or assume) design intent within your models and assemblies, but that does not mean that the geometry kernel will have the power to solve the geometric problems driven through the parameters. In this case CoCreate Modeling was able to perform the required changes to the crankshaft and rod even though they were imported models with no history-tree.

Paul

If interested to learn more about direct history-free modeling, my team and I will be at PTC/User in Orlando in June. We will be presenting many topics related to history-free design, and also providing some free user training on CoCreate Modeling. Check it out at www.ptcuser.com.

History-Free CAD, Much More than Direct Editing

2009-03-31T13:00:00.000-06:00

Most all major CAD companies are now selling or developing history free, direct, explicit, (whatever you want to call it) technologies. Most of the talk is related to how this technology can bring new flexibility to the geometry editing process regardless of how or where the geometry originated. What I don’t see being discussed much is how history-free technology can be utilized to actually design products. There are many characteristics of history-free technology that can bring new and flexible approaches to the design process if implemented properly. It can be much more than direct editing.

There are several characteristics of typical history-based CAD systems that, to some extent, impose rigid methods and process into the task of creating models, and eventually designing products. Most of these characteristics have been common place in 3D CAD for so many years that we really don’t consider them as being something that may inhibit our ability to actually design products. With history-based CAD, a user is creating a “program” (usually called a history tree) that if done properly will represent the product design. Because of this a user must be careful and cautious in creating and manipulating the program. But not only that, the CAD system must closely control how it is being used to develop this program; otherwise the program (history tree) could easily be corrupted. Here are just a few of these characteristics.

In most training manuals for history-based CAD systems you will find early on that users are coached and encouraged to spend some time in up-front thought and planning before beginning the actual modeling process. To create the “program” (history tree) correctly you must know something about the “intent” of the program. What dimensions are critical for the design? What dimensions and parameters might change throughout the lifecycle? What relationships are critical to the design? In reality, with history-based CAD you may be “documenting” what is already designed more than you are actually “designing”. As there is no recorded tree or “program” with history-free CAD, there is no need for up-front planning. Just quickly get into the process of design.

In history-based CAD, the sketch is a critical component in the tree. Each sketch creates a feature that is ordered in the tree. Too much complexity in the sketch can make editing difficult, too little can lead to overly complex and large trees. With history-free CAD a sketch can have as little or as much complexity with no impact to the end results. Complex nested profiles are just a valid as a simple rectangle.

There are some modeling operations that don't come natural when working in a history-based environment. Operations like Unite or Merge for joining two parts together into one part, or Section for cutting one part into two new parts, (don’t confuse this with the interaction between multi-bodies of a single part). These functions can be very useful and will allow users to leverage and take full advantage of existing 3D data. If these functions do exist in the assembly mode of a history-based CAD system, they will be tightly controlled and somewhat inflexible, and in the end may overly complicate the history-tree. How geometry is created makes no difference in a history-free CAD system. In a mature history-free CAD system you should find many geometry creation and modification functions that can bring much flexibility and productivity to the design process.

As mentioned in an earlier post about in-context design, history-based CAD systems must have a part mode and an assembly mode. This can significantly complicate the process of product design. Special functionality is required to make top-down and in-context design possible in history-based CAD. With mature history-free CAD there will be no part mode or assembly mode, you will be working in a virtual 3D space. In-context and top-down is just the natural way of working.

History-based CAD provides a nice platform for capturing so called design intent. As a matter of fact, with history-based CAD you are capturing and managing much of this intelligence whether it is needed or not. With mature history-free CAD, you should be able to add and utilize design intent where and when it makes sense including constraints, relationships, dimensions, tolerances, features and other annotation. Combining parametric modeling with history-free modeling is nothing new.

There are several other characteristics that fit here, but these are some of the more obvious.

Combining history-free, direct editing technologies into a history-based CAD system will not reduce, minimize or eliminate these characteristics and their impact on the design process. If the CAD system records modeling and assembly operations in a tree structure, these characteristics will exist.

If you are interested in the potential benefits of history-free "design", be sure to look for the following characteristics.

There should be no need for up-front planning.
There should be complete flexibility in sketching. The sketch should have no impact to the future use of the model.
There should be a variety of methods for creating and modifying geometry with complete flexibility in how it's done.
There should be no part mode or assembly mode. In-context and/or top-down should be natural and normal.
You should be able to add and utilize design intent where and when it makes sense.
Oh, and I don’t want to forget – you should be able to directly edit geometry regardless of where and how it was created.

And now for the usual disclaimer: History-free CAD is not for everyone. It’s not the answer to all your design needs, and it is certainly not the only tool you may need in your product design toolbox. It can however bring much more value to the process of product design than just direct editing. It just depends on how it's implemented within the CAD system.

Paul

Design In-Context - What's the Big Deal?

2009-03-16T08:10:00.000-06:00

In-context design is a term used to describe the process of creating models of parts and assemblies within the context of other parts and assemblies. Recently I have been forcing myself to spend more time using several of the more popular history-based tools just to make sure I still have some understanding of the “other side”. While doing this I am learning that I have been taking for granted the ability to easily and almost unconsciously do in-context design within my usual history-free environment, which in my case is typically CoCreate Modeling.

With most parametric history-based modeling tools (and maybe all) there are two modes that users work in; part modeling mode and assembly modeling mode. One of the first things you must do after starting up one of these history-based applications is to decide whether you will be working with a part or an assembly. This is so frustrating to me, but it does make sense considering history-based technology. Keeping these two environments separate is important with a history-based system. The system needs to know which part history tree or which assembly history tree the modeling operation will be recorded into. Because of the need for two separate environments, in-context design is naturally a challenge for a history-based system. Makers of history-based CAD systems have had to develop specific functionality to work around the related complexities that come with history-based in-context design. But even with the special functionality and workarounds, users still need to be somewhat careful when taking advantage of these special capabilities.

With a history-free design system, there is no need to have two separate environments, one for part modeling and one for assembly modeling; since there is no history tree to manage. Users can always create parts and assemblies in context and simultaneously. History-free design systems provide a very natural environment for top-down or in-context design. No special functionality or workarounds need to exist. It’s like working on your desk with physical parts. In this environment an assembly is just a structure. Parts and subassemblies can be placed into the assembly structure anytime. Once in the structure, the owning assembly manages the positions and relationships of the parts and subassemblies.

Here is just a simple demonstration showing an example of in-context design using PTC CoCreate Modeling. A few key points to watch for during the demo:

Creating multiple, unique parts in one modeling operation
Modifying multiple parts with one sketch and one modeling operation
Modifying multiple parts with many sketches in one operation
Modifying a part by referencing geometry from another part
Moving multiple parts while modifying a part, in one operation, without constraints
Manipulating assemblies and parts in one environment

In-Context Design with CoCreate Modeling

This demo seems so simple and trivial to me, but I can’t figure out how to do the same with any of the history-based systems I've been using. Can it be done? I know that with some of the history-based tools you can create multi-body parts, and then extract one of those bodies as a part, but the resulting part turns into a dumb solid with no history. Can history-based in-context design really be that difficult? I guess so.

Paul

Feature Recognition and Direct Editing

2009-03-04T08:00:00.000-07:00

Three dimensional automatic feature recognition technologies have been around for at least 20 years. There are many uses for feature recognition in our industry. Makers of parametric history-based modeling systems have attempted to use feature recognition capabilities to turn “dumb” imported solid models into feature-based solids. CAM vendors have used feature recognition to automatically identify holes, slots, pockets and bosses in 3D geometry to help automate the process of tool path generation.

While useful for the two cases mentioned above, feature recognition is critical to good direct editing and history-free design. Direct editing functions require that a face or collection of faces be passed to the edit function (for some functions, it may be edges). There are a variety of ways that a face or collection of faces can be identified. Certainly you can select one face at a time. Some systems allow for a viewport box select. There is also what I call conditional recognition, where geometry is selected based on conditions such as tangent, adjacent, coincident and so on. And then there is feature recognition. Robust, predictictable feature recognition can greatly speed the process of direct editing.

Automatic feature recognition will require the user to select a single face; some call this the seed face. The feature recognition algorithm will start with the seed face and walk through the topology of a solid model looking for very specific conditions and regularities in the topology to identify a useful collection of faces, perhaps representing a hole, a boss, a pocket or perhaps a rib or slot. The term “Automatic” should already tell you that the results may not always align with expectations, but good robust feature recognition should deliver predictable results.

The above images show a fairly complex rib in a portable drill case. With one pick on a side face of the rib, the feature recognition algorithm walks through the topology to find specific conditions and then provides the highlighted results. In this situation the algorithm has recognized all of the other faces associated with the rib, even though the rib intersects with multiple other faces. Without this capability the user would have to try to box select the entire rib, most likely getting too many other faces from the same region, or perhaps select each face individually. Now that these faces are selected they can be passed to, or consumed by, an edit function – perhaps move it, taper it, make it thicker or thinner, copy and paste it somewhere else, or even remove it. It just depends on what direct edit functions are available in the system and how robust they are. Since feature recognition is topology based, it will work the same for any 3D geometry format such as IGES, STEP, SAT or native.

Each CAD system today has different concepts and capabilities of feature recognition. With parametric history-based CAD systems, multiple face selection really does not apply as modifications are done through preexisting parameters and feature definitions. However it certainly can apply and be very useful for the direct editing functions, depending on the direct editing capabilities. Most of these systems do have direct editing capabilities now, but very few of them have useful tools like feature recognition to help with face selection. NX seems to have a reasonable collection of conditional and feature recognition capabilities and I am sure we will see others follow.

For history-free systems, feature recognition becomes very important. With all history-free CAD systems you will drive many edits by selecting the geometry to edit and then specify the modification, (an exception may be when driving change through parameters and/or dimensions). The geometry selection process can be simplified with good feature recognition. CoCreate Modeling, SpaceClaim and KeyCreator all have good feature recognition capabilities, although there are some significant differences in how they work and how robust they are. These systems also come with a good variety of conditional recognition capabilities.

It is a bit interesting to see how differently these algorithms actually work from one system to the other. If you are considering direct editing within a parametric history-based system as an important tool for your product design process, or perhaps considering history-free design, it would be good to spend a bit of time evaluating this capability. Good feature recognition can save a fair amount of time while making those needed modifications. Don’t forget to check it out.

Paul

Is History-Free Design For Real?

2009-02-23T08:00:00.000-07:00

I get the feeling that many people view history-free, explicit, direct modeling (whatever you want to call it) as some new experiment that may or may not make it in the market. It seems that some think you really can’t do serious design work with it, that it is something only useful when simple edits are needed with non-native CAD data or when history trees get too cumbersome. This may be due to the fact that some history-free technologies, including some that have recently been introduced, are in fact better suited for simple geometry editing rather than full on product design.

Flexible robust history-free modeling technology has been used all around the globe for the last fifteen years (or more) to design hundreds of thousands of successful products. As an example, most all of the printers you see on the shelves at Best Buy are designed, from concept to detail, using history-free modeling technology. It is real and it does work, for many companies. The percentage of companies using history-free technology for product design is certainly smaller than that of companies using history-based technology, but product design with the help of history-free technology is growing rapidly.

Just talking for PTC CoCreate Modeling, PTC claims that there are over 57,000 companies around the globe using CoCreate Modeling to design products. Most of these moved from history-based modeling after recognizing that history-free modeling better supported their processes than did history-based. I can tell you that most of these companies know intimately the benefits of history-based modeling, but they chose history-free, usually based on process and product requirements. There are certainly some that tried it and moved back, but the number of companies using history-free technologies for product design is growing. I would suspect that the same is true for Kubotek and SpaceClaim. This explains why other CAD vendors are trying to introduce similar capabilities as quickly as possible.

Here is a quick collage of images that represent a small fraction of a percent of real, successful products that have been brought to market with the help of history-free modeling (courtesy of the PTC CoCreate web site). From Aerospace to automotive, from high-tech electronics to machinery. They have all realized the benefits of history-free product design, and continue to bring innovative products to the market in a competitive, timely and successful manor - without a history tree.

Using history-free modeling for product design is not some new concept. It is real and has been proven to help many companies around the globe innovate and successfully compete in their market.

History-free does not mean that you have to give up design intent. CoCreate Modeling, as well as a few other tools, allow for 3D features, constraints, parameters, driving and driven dimensions, tolerances, GD&T, and annotation, all directly on the 3D parts and assemblies. History-free simply means that you are interacting directly with geometry rather than through the recorded sketches, parameters and features that are structured in the typical history tree during the modeling process. It doesn't fit every company, but it would be wise to be sure you are using the best tools to support your processes and requirements.

Now for a commercial: If you would actually like to try history-free design, PTC is hosting two free hands-on workshops coming up in mid March. March 17 in San Jose and March 19 in Boston (Needham). I will be at each and will be providing a quick presentation on the technologies and the benefits to product development, and then you will spend the rest of the time with some hands-on introduction and training. Should be a fun time. So if you are in the area, please stop by. Here is a link to the registration.

http://tinyurl.com/bt2rx7

Oh, and it looks like they are giving away a Nintendo Wii to some lucky attendee. (Maybe if we get tired of modeling we can bowl)

Paul

The Maturity Curve of Product Development

2009-02-16T08:00:00.000-07:00

Throughout my career I have had the privilege of visiting a great many different product development and manufacturing companies, from Ford, Boeing and other giants to the small mom-&-pop shops. From high-tech to aerospace to automotive and machinery. (I’m actually writing this while on another airplane coming home from more visits) I find it fascinating and enjoyable to take tours and talk to people about their responsibilities and how they fit into the greater process of product development. Also of interest to me are the types of tools these people use to support their responsibility and the greater process. Tools can be put into three simple categories; creators, managers and consumers. Of course, most are some combination of all three, but will most likely focus on one more than another. So how do the tools support the process and how well does the process deliver to the business objectives?

Throughout my visits I have seen the spectrum. From drafting boards (yes, they still exist) to the total absence of 2D drawings (although still very rare). I’ve tried to capture this spectrum in what I call my product development maturity curve, or - whatever. There are certainly a thousand different ways to look at it, but this is mine, (so far):

There seems to be two basic factors that drive companies up the curve; #1: the business – basically the objectives and drivers associated with successfully competing in the business you are in, and, #2: the desire and willingness to excel. #1 is something that every company has to deal with, but will not necessarily drive your processes up the curve. #2 is also required to make the move, but unfortunately is often considered optional and is pushed back or neglected in favor of getting things done by the safe tried and true methods, i.e.; there is always a risk/cost associated with “change” and “new”. There are many reasons for not moving up the curve. The following are some of the reasons given to me by many of the companies that I have visited. “Our piece/parts are so simple we really don’t need to move up.” “Our culture and personnel are just not ready; it would cause too much chaos.” “We are in a highly regulated industry that keeps us where we are.” “Our supply chain cannot support the move up.” “We are starting a new important project and just don’t have the time.” These are all real and to some extent valid, although they are not inhibitors, as witnessed in several other companies.

The usual question to ask when considering a move up the curve is; what will be gained by making a move up and at what cost?

This question should quickly take you back to:

What are your business objectives and do your processes deliver to those objectives? Is there any way to improve process to better deliver on business objectives? Can process improvements be staged to minimize disruption? What benefits can be gained – improvements, reductions, …? What is the value?

Then:

Are the right toolsets in place to support the proposed process improvement? What tools will need to be replaced? What tools will need to be added? How will culture, practices and personnel need to change? What is the cost?

And last, but not least; what is the ROI? (There, I just put several months of work into a few simple sentences)

I can tell you that in just the last two months, three of the companies that I have visited are experiencing budget and schedule overruns in their PLM and/or xRP deployments. And in every case the reason given, after asking a few probing questions, was that they too quickly jumped to the solution (tool) before looking in more detail at the business drivers, existing processes, process requirements, culture, – and – the future. In all three cases there was a desire, and a budget, to progress up the curve. But unfortunately the cost will now far exceed the benefit, for the foreseeable future.

PLM is typically viewed as a “manager” toolset, like the name suggests, (of course there are also elements of creation and consumption in PLM). As such it is obvious how it can impact process and if structured and deployed properly can support a move up the maturity curve, (as a matter of fact you cannot be successful in stage III without it). The “creator” tools also have a huge impact on process and the ability to move up the curve.

The “creator” tools can be used to create massive amounts of data. Can this data be managed properly so that it can be found, understood and extracted as needed throughout the process and its lifecycle? Is the data managed in such a way that it will support a move up the curve? Can the data be consumed as needed throughout the lifecycle to get the maximum value from it? Will it be consumable, of value, and support the future move up the curve?

In product development, one of your biggest “creators” is the CAD tool. Besides geometry, there is a significant amount of data that is also created and associated with this geometry. Stuff like history-trees, sketches, features, parameters, view sets, drawings, 3D dimensions/tolerances/notes, 2D dimensions/tolerances/notes, title blocks, FEA results, engineering calculations, tool paths, animations, images and so on. Consider the data that is being created, the time that is invested to create it, the infrastructure needed to support and manage it and the various tools that can “consume” it and generate value from it. What is the cost and what is the value? Will it support/enable or inhibit the move up the curve? Some of your data may be like the music on an old 8-track tape – the data is there, it may be good (probably not), and it is likely you will never be able to get any value from it again.

What I see to be much too common as I visit companies is the tendency for the selection of tools to be weighted heavily by the preference of the IT organization and/or the users. These people are certainly very intelligent and most likely have the best interest of the company in mind as they make these decisions, but unfortunately as recognized by the three examples mentioned earlier, business drivers, process requirements and a clear vision for the future, are often weighted lower than other criteria in the selection process. Shouldn’t these be at the top?

Where does your company fit on the curve? Where do you need to be to compete in your business today – next year, and the next? Are you paving the way, or are you just trying to survive by tried and true methods? Are you moving up the curve? It’s a good bet that your competitors are.

Paul

Inventor Fusion – More ConFusion

2009-02-09T11:00:00.000-07:00

I'm pulling a few quotes for an article by Kenneth Wong published at Desktop Engineering. The title of the article is: “Autodesk Joins the Hybrid CAD Movement with Inventor Fusion". Has Autodesk solved the unsolvable?

Comment #1:

“So what distinguishes Inventor Fusion’s underlying technology from its rival Synchronous Technology, made available via Siemens’ NX and Solid Edge software? The answer is, in Anagnost’s words, “a two-way street; the ability to move back and forth seamlessly between the two modeling paradigms.””

When creating 3D geometry, a CAD system is either capturing information about the modeling operation; history-based, or it is not; history-free. When editing, you are either editing the captured information resulting in different geometry, or you are directly editing the geometry. It really is that simple. Some argue with me on this, but how can it capture and not capture at the same time? It can get a bit more complicated with direct edits within a history-based system. These edits (including information about the edit) are usually captured within the tree to preserve them during the next regeneration of the tree. The exception is when a parameter of an existing modeling feature, within the tree, is dynamically and graphically changed and it appears to the eye as a “direct edit”. In any case the rule still applies. So how do you “move back and forth seamlessly between the two modeling paradigms” of creating history and not creating history, or perhaps editing history or editing geometry? Hum... Sounds confusing to me.

Comment #2:

“Anagnost says, with Inventor Fusion, you can make a change using direct editing, but if you wish to parametrically refine the geometry deformation after the fact, you may go back to the feature tree to modify the parameters. He clarifies that Inventor Fusion automatically figures out the parametric modeling steps necessary to accomplish the direct edits, “including the order of dependencies.””

This comment only refers to editing geometry, so maybe I'm making the incorrect assumption that you can actually create geometry/parts using Inventor Fusion. Maybe it is just an editing tool. The comment: “Inventor Fusion automatically figures out the parametric modeling steps necessary to accomplish the direct edits, “including the order of dependencies.”” would indicate that Autodesk has solved a very complex problem that many companies for many years, including SolidWorks, have been trying to solve: the ability to scan a dumb solid, or partially dumb solid, and build a useful feature tree, including parameters, that fits the users design intent. This statement would indicate that Inventor Fusion has the capability to walk through the topology of a solid model and identify and recognize meaningful features from it (this is nothing new: feature recognition). Then it would be able to create and associate sketches (if needed), parameters and conditions to these recognized features. Then, order the features in a meaningful and useful way. And it would all need to be done in a way that would fit the users design intent - “automatically”. This would be very cool, but I kind of doubt it – show me.

Comment #3

"Dan Staples, director of Solid Edge development at Siemens, says, “If you make a decision to move to Synchronous Technology’s way of modeling, you actually have no reason to revert back to the traditional way of modeling. Synchronous Technology is a superset of technologies.”"

When you move from “History Mode” to “History Free Mode” in NX or Solid Edge, you lose the history tree, and the system will clearly warn you of this. With Synchronous Technology you can still parametrically control the history-free model, ("superset of technologies", i.e. parametrics with history-free modeling), just like you can in CoCreate Modeling, but you do lose the tree. With ST you can toggle back to “History Mode”, but it will not and cannot recreate a useful tree and feature structure from the history-free “dumb” model. As such there is infact, as Dan states, "no reason to revert back”. The term "superset of technologies" is refering to the combination of parametrics with history-free modeling, not history-based with history-free. Combining parametrics with history-free modeling is something that most all history-free systems on the market can already do. It's nothing new, although ST does a nice job of it. Are these guys talking about the same thing? "two modeling paradigms"? "superset of technologies"? I'm confused.

It is great to see Autodesk jumping on the direct modeling wagon to further validate the need for more intuitive and flexible modeling tools, and it will certainly be enjoyable to watch as things mature. Maybe they really have invented some amazing new technology. We will watch and see. Just don’t get too excited or perhaps baffled by all the flashy marketing stuff.

Paul

SpaceClaim Response to My Topology Review

2009-02-02T18:00:00.000-07:00

SpaceClaim requested the part that I used for the History-Free shootout in my last post. I sent the part to them along with the move positions and they quickly sent the following response. Thanks to Blake Courter of SpaceClaim for taking the time to do this.

As I mentioned in the post, I was moving the features only using the default settings and options, for all three systems. Blake points out here that there is an easy option in the Move function of SpaceClaim to solve some of the more complex topology problems. Since history-free modeling features do not have a “recipe” associated with them to tell them how to behave, it is important for the history-free system to offer options such as what SpaceClaim is showing below. This can provide more flexibility for managing the possible results.

Below are Blake’s comments and images

-------

Hey Paul,

Here are my findings on your part. I did use our Detach First option on most edits, because this option is optimized for longer walks across topology.

#3: It seems that when all three are moved the exact same distance, we get a slightly different result. This did not show up when I wasn’t using your test part.

#5: Everything works beautifully with Detach First on.

#6: Everything works beautifully with Detach First on.

#8: I didn’t see any order-related problems. With Detach First, we get holes in the top fin, which are easy to fill.

#9: Everything works beautifully with Detach First on.

#10: With Detach First on, we get holes on top. Easy to fill. Otherwise they stay put. This is a great example of why we have the Detach First option.

#11: With Detach First on, we get holes in the fin, but there doesn’t appear to be any order-depended problem.

#12: We get a different result with Detach First on. Another great example of how the option helps.

#13: Cool thing with Detach First: the holes leave surfaces behind so you can move other objects and then reuse the surfaces to make the holes again.

R&D tells me that the default behavior is even smarter with our next release, but I think that the important points are:

It is easy to make all of these edits.
Topology changes are usually ambiguous. Even if you don’t get exactly the result you expect, it is easy to adjust the given result into the one you want.
Some of the issues you had appear specific to your test part, and we suspect they are less likely in the field.

Best,

-Blake

History-Free Modeling Shootout

2009-01-29T16:00:00.000-07:00

Round 1: Simple Topology Changes.

When using history-free explicit modeling technology, controlling topology of a solid model and doing it in a way that applies to the needs of engineers and designers is not trivial. Changing geometry can be simple, but when those geometry changes impact the topology of the solid model, things can get complex very quickly. Since there is no recipe behind the features, the system must be intelligent enough to make sense of the topology as edits are being made. The ability to properly manage the topology of a B-Rep solid model is at the heart of effective history-free modeling.

I had the rare opportunity to use three of the history-free CAD systems several days ago and wasted some time playing with them. I noticed that each was behaving slightly different when making some modifications to the parts. I then setup a test part to try and get a more detailed and consistent look at it.

In this case I am only looking at how these systems handle topology as simple features are moved from one simple face to other faces and edges resulting in a topology change. As such this test may not mean much to most of you, but I found it interesting. Also, considering how fast this technology is changing, this particular test may be obsolete in a few months.

The part I used looks nothing like a part you would design in real life, but I created it so that it would include representations of a few of the more simple topological conditions that you will find in the parts that you design. I just put them all into one part for the test. To make it fair, I created the STEP file in Autodesk Inventor and used this same STEP file in all three systems.

You can see the part below. It has a simple boss, hole and a pocket on one side of the part. My test is to position these three features in different locations and check the results. Each position represents a different topology challenge. I purposely left blends/rounds off the part as in this case I’m not interested in the blend algorithms, but rather focusing only on the topology management capabilities of these three systems.

Even though some of the tests may not have worked so well or perhaps failed, the wonderful thing about history-free explicit modeling is that you can always undo and easily and quickly slice and dice to get the results you want. With a history-based system, if you don’t get the results you want, you have two options: 1) go through what can be a mind-numbing maze of interlocking relationships and constraints in the history tree to find and hopefully fix the problem or, 2) rebuild the model from the start. Actually there is a 3rd option IF the system provides robust direct editing capabilities that can properly manage the needed topology challenges.

In my test results you will see 3 images for each test:

On the left: PTC CoCreate Modeling 2008 (CC)

In the center: SpaceClaim 2008 SP4 (SC)

And on the right: Siemens NX6 with Synchronous Technology (ST)

This was a fairly simple test requiring very little knowledge of the CAD system. I just used one simple part and one command with nothing but the default options for all three systems. I used a variety of selection methods, selecting individual faces, boxing in the faces or using the system’s ability to recognize features, whatever provided the best result. The only command I used was the “Move” (in CC & SC) and “Move Face” (in ST). In each case I start the move from the original position.

So here we go.

Test #1 – Intersect with a face above the base face.
(Note: “base face” refers to the face that the features are attached to previous to the move.)

CC – The move works as expected.
SC – The move works as expected.
ST – The hole and pocket do not extend above the base face.
(Note: The term “as expected” refers to MY expectations, you may have other expectations)

Test #2 – Step up to a higher face.

CC – The move worked as expected.
SC – The move worked as expected.
ST – The move worked as expected.

Test #3 – Intersect with a taller face and a face that is lower than the orginal base face.

CC – The move worked as expected.
SC – The hole did not extend above the base face. This move was order dependent. If I moved the boss first then the hole, the part would look as displayed, if I moved the hole first then the boss, much of the part would be trimmed away. There is some strange interaction between the features.
ST – The boss would not extend to the lower face. If I moved it even another .1mm it would extend.

Test #4 – Intersects with a face that is lower than the base face, and lower than the bottom of the pocket.

CC – The move worked as expected.
SC – The move worked as expected.
ST – The move worked as expected.

Test #5 - Intersects with a higher edge and two faces.

CC – The move works as expected.
SC – Neither the hole or pocket would move to the desired location.
ST – The move works as expected.

Test #6 – Intersects with a lower edge and two faces. (The edge is at the same depth as the pocket)

CC – The move works as expected.
SC – Pocket and hole would move, but not the boss. Opposite of test #5.
ST – Pocket did not extend into left side of groove.

Test #7 – Intersects with a face that tapers from below to above the base face.

CC – The move works as expected.
SC – The move works as expected.
ST – The move works as expected.

Test #8 – Intersects with top shelf and a bottom face that is below base face.

CC – The move works as expected.
SC – The move works as expected, although I had to move the features in a particular order otherwise I would get the results in the smaller image.
ST – Pocket and hole moved good but I could not get the boss to move into the top faces.

Test #9 – Intersect with a thin wall. The bottom face is below the base face.

CC – The move works as expected.
SC – Boss worked well, but the hole and pocket extended through the sides of the shelves. I had to move the boss first otherwise much of the part was trimmed away.
ST – I could move the boss, but it would only extend into the lower right side of the wall. I could not move the hole or pocket.

Test #10 – Intersects with mid-shelf. The bottom face is below the base face.

CC – The boss extends through the top side of the shelf. The hole and pocket do not extend into the shelf. (If I select individual faces rather than a recognized feature, the hole and pocket will extend into the shelf.)
SC – The boss extends through both sides of the shelf. The hole and pocket do not extend into the shelf.
ST – The hole and pocket move ok but the boss will not move off the wall.

(not sure if CC or SC is right. I will give it to SC as it can often be easier to remove geometry than add)

Test #11 – Intersects with an angled wall.

CC – The boss extends through the top side of the wall.
SC – The boss extends through both sides of the wall and to the lower floor. Again, in this case I had to move the boss first otherwise much of the part would be trimmed away.
ST – Same as before, you can see how far the features will move, but from that point it failed.

(the comment in #10 applies here as well)

Test #12 – Intersects with the end of the part.

CC – Pocket and hole extend nicely. Boss extends out the end of the part.
SC – Pocket and hole extend nicely. Boss is trimmed by end face. In this case I had to move the boss last to get acceptable results.
ST – Pocket and hole extend nicely. Boss is trimmed by angled face on left side. If I move it just a fraction more the boss will be trimmed by end face.

(Not sure which one is right)

Test #13 – Pull features off part.

CC – Negative space features disappear as expected. If positive space features are pulled off the part and are not attached to a different part, they become a separate and new part.
SC – All features disappear, including the boss.
ST – You cannot pull the features off the part.

All 3 systems allow you to copy and paste features if you actually want a new copy of the feature.

OK, One last test, (and congratulations if you actually made it this far).

Test #14
If you want a more realistic test consider this part, a fairly typical plastic part. In this part there are many areas that have similar topology challenges as to the test part above. For this test I loaded the same STEP file into each system. I then selected the snap feature colored brown and tried to move it to another location, again only using the Move command. The new location of the snap feature will involve a complete new set of faces and topology that it will intersect with. It will need to be both trimmed and extended during the edit as it moves from curved surfaces to planar faces.

CoCreate
The move worked very easy and very fast. With CC you can also use the “keep feature” option of the Move command so that the original will be retained and a new copy will be created as the feature is moved (inset). Notice that all faces are properly trimmed and extended, no additional work is needed. Whether you “keep feature” or not the move works, simple and fast.

SpaceClaim
With SC I could not move the snap feature more than a few tenths of a millimeter. I was very careful to select only the faces that make up the feature, using the Protrusion selection option, and to select the same move direction, but i could not get it to make the move. By using the Ctrl key during the move, SpaceClaim will create a copy. Using this method I was able to move the copy into the desired location. It was properly trimmed and extended as needed. It was a bit slow and touchy, but the copy/move worked.

NX6
Like SC, with ST I could only get the snap feature to move about .5mm in either direction. I tried many times being very careful that I selected only the faces that make up the feature and to select the same move direction. In NX you can copy the faces that represent the snap feature, then paste them and move the results. The pasted set of faces do not make up a solid so you will need to make a solid out of it, unite it and trim it as needed.

Summary
I purposely am not going to make any summaries of the above findings, for a few reasons. First of all I work for PTC so you wouldn’t believe me anyways :<). And secondly, it is entirely up to you to determine which, if any, of these tests would impact you considering the type of CAD work you do and the characteristics of your parts. I did learn a lot about the 3 systems, the different selection methods they provide, the many differences in their feature recognition capabilities and the various methods for specifying the transformations. It was certainly interesting.

I will say this, with any one of these three systems I can get the expected results for all 14 cases. It’s just that some edits may require a few more minutes of cutting and pulling to do it. That’s the nice thing about history-free explicit modeling.

There is certainly more to a capable CAD system than this, but being able to properly manage topology during edits will have a big impact on your ability to get things done in a timely manner. A nice UI, convenient selection methods, synchronous relationships, design intent, integration of other applications, and other capabilities won’t mean much if the system can’t manage the topology in a useful manor.

If I get the privilege of a Round 2, I would like to see how these systems manage topology when the feature isn’t so nicely contained inside one simple face, but rather intersects several faces before the move – leaving a more complex hole to fill.

So, if I was going to score it, this is how I would do it:

I am certainly open for the real product experts to comment on how to make these tests work better in their application. But in the end I am more hoping that this can have some impact on making history-free modeling even more robust than it already is.

Paul

Reducing Costs with Explicit History-Free Modeling

2009-01-26T09:01:00.000-07:00

History-free modeling is not for every design and manufacturing company. But, depending on the types of products you develop and the supporting processes, you may be one of many companies that can realize great cost savings by utilizing explicit history-free modeling for your CAD work. With the economy as it is you must be looking for ways to reduce costs. I recently posted some of the unique benefits of history-based modeling, which if properly taken advantage of, can contribute to better efficiency in the process. Below are some of the unique benefits of explicit history-free modeling that, if it fits the process, can deliver improved efficiency and reduce waste (lean), and NOW is the time to consider this.

10 Ways to Improve Efficiency

Lower your training costs with history-free modeling. There is simply less to learn when there is no history tree to create and manage. Intuitively interact with the geometry, directly.
Get the right people engaged at the right time. Eliminate CAD knowledge from the criteria for assignments and resource management.
Hire the best designers and engineers, not just CAD jockeys. Eliminate CAD knowledge from the criteria for hiring/staffing.
Enhance the concept design process with flexible 3D modeling. Concept design and history-based modeling are like “oil & water”; they don’t go together very well.
Improve productivity for each individual by focusing on design, rather than model creation methods, technique and process. Reduce costs by focusing all effort on product design rather than 3D modeling.
Repurpose existing data easily with no need to understand model history. Optimize parts once and reuse to the max.
Greatly improve teamwork, team design and interaction with downstream and upstream partners to improve quality, innovation and reduce costs. By eliminating the history tree, team members can immediately interact with the CAD data. No need to study the model history.
Get the maximum value from your rich CAD data by making it available, and understandable, to the extended team.
Minimize IT infrastructure load. Utilizing explicit history-free modeling technology can reduce average file size by 60% to 80%. Can minimize RAM requirements, storage space requirements and network traffic. This is made possible by eliminating data space requirements that are typical of the history tree.
Improved general performance and load/store times for each CAD user by taking advantage of the lightweight footprint of explicit history-free modeling.

10 Ways to Reduce Waste

Eliminate the waste of history tree management and structuring. Focus on the task of design. And don’t make the incorrect assumption that you cannot capture design intent without a history tree.
Eliminate the need to rebuild models, something that is too common with history-based tools. (especially if you do concept design with them)
Eliminate the need to create and manage standards and best practices for creating and managing history trees / history-based models.
Add intelligence (features, parameters, …) to models and assemblies only when needed. History-based systems may force the addition of this intelligence whether it will be used or not. They will force relationships (parent/child), again whether this added information is actually useful or not.
Upward compatibility can be a big issue with history-based modeling and can result in rework and duplication of effort. There is no compatibility issue when working with geometry; i.e. explicit history-free modeling.
Greatly reduce the effort of data exchange with suppliers and vendors. History trees are proprietary.
Eliminate the need for other team members to study the history tree of other team member models just to make use of them.
Designers will spend an estimated 25% of their “CAD time” managing and manipulating the history tree and related attributes and data. Your designers can be 25% more productive by eliminating this activity.
Greatly reduce the need to recreate CAD data just to get it into an editable format
Reduce the time consumed in the change cycle, but eliminating the need to study the model creation history. Focus on the process of change.

There, I made it – 10 for each, although there is a little overlap. Some of you that have experience with history-free modeling can probably throw a few more in here.

Again, your processes/products may require some of what is suggested above as something to eliminate or reduce. If that is the case, history-free modeling may not be for you. But I challenge you to take a close look at your CAD requirements based on processes and product characteristics, rather than personal habits and preferences.

Paul

The Unique Benefits of History-Based Modeling

2009-01-06T11:30:00.000-07:00

As the awareness of history-free modeling increases, there seems to be a growing desire to somehow merge the benefits of history-based modeling with the benefits of history-free modeling. This may be a bit difficult to consider as we may all have slightly different ideas on what benefits each of these technologies bring to our own CAD requirements. As we consider these technologies we should try to be specific about how they may or may not support our requirements. Much talk has been made regarding the benefits of history-free modeling, but what are the benefits of history-based modeling that we may miss by moving to a history-free environment? As an example, Siemens with Synchronous Technology makes it easy to switch, but what benefits will you miss out on by doing so?

I added the following comments in a previous blog, but I want to restate them for the purpose of this discussion. There are a few absolutes regarding CAD technology.

A CAD system is either history-based, i.e. tracks the modeling history (features are ordered with a parent/child relationship) OR it is history-free, i.e. does not track history (explicit or direct with no parent child relationship). If it has history, it is not history-free. Features are either ordered or they are not. Once history is gone, it is permanently gone – there is no getting it back without starting over.

A CAD system either has parametric capabilities (constraints) or it does not. It doesn't matter if it is history-based or history-free. Parametric capabilities can exist in both history-based and history-free modeling. The capability either exists or it doesn't.

A CAD system either has direct geometry editing capabilities, or it doesn't. A history-free CAD system depends on direct editing, (it can’t exist without it). For a history-based system, direct editing is a nice to have feature. In both cases, history-based or history-free, the direct editing capabilities will apply to both native and imported data.

In my enthusiasm for history-free modeling I certainly have not kept my opinions secret with regards to the positives of history-free modeling (or the negatives of history-based modeling). However, history-free modeling still may not satisfy all of your requirements. Today it cannot replace all of the benefits of history-based modeling. A few years ago, the list of unique benefits of history-based modeling as compared to history-free modeling, was a long list. Today the list is much shorter, but there is still a list. With this post I will try to describe some of these remaining benefits. I hope others will add to the list, but keep in mind I am only referring to the benefits that come from a history-based system, specifically the ordered feature tree with its parent/child relationships, as compared to todays history-free technology. There are certainly many other criteria to consider when evaluating a CAD tool.

So what benefits can be realized from "ordered" modeling features that are not available in the history-free environment (no order)? That’s the question. Here are the ones I’ve considered.

The “Shell” is an obvious modeling feature that benefits from a parent/child relationship. When a change is made to the parent, the child feature (shell) will conform to the modified parent during the model regeneration. So far there is not a common method in history-free modeling for managing a consistent wall thickness on a part. At this time the current history-free modeling systems each handle this problem a little differently. While you get much more flexibility in your shell with history-free modeling you don’t get the natural consistency that comes with the shell feature when properly structured in a history tree.

Support for multiple states, i.e. secondary operations (stock-finish). There could be two different states such as a cast part that is machined. Or perhaps even three states such as individual parts that are welded into one and then machined. In these situations a part exists in more than one state, but from a design intent point-of-view you want to utilize the same geometry wherever possible such that a change to geometry in the first state is realized in the second state, and so on, i.e. associativity from one state to the next. By properly structuring the history tree and the related parent/child relationships, you can support this requirement fairly well with a history-based system. Features can be added/suppressed allowing the representation of a part in different states. There are ways to solve this in a history-free environment but to date I have not seen a good solution for it, although I don’t think it is too far away.

Ease of controlling a model/assembly parametrically. Parametric modeling is completely possible in a history-free model or assembly. It is nothing new. The reason I keep this benefit on the list is not that it can’t be done in a history-free environment, but rather that it is still somewhat easier to capture this information by properly utilizing the parent/child relationship. The parent/child relationship seems to make it a bit more intuitive when we want to drive the effects of one parameter into different areas of the part or assembly. This translates into the ability to more intuitively support requirements for family-of-parts, configure-to-order or perhaps design optimization. This benefit may have more to do with "familiarity" than being "intuitive".

Ease of controlling freeform shapes and surfaces in a solid model. There is very mature technology out there for defining and controlling freeform surfaces without the need for history. Surface modeling systems have been doing it for years. Controlling freeform surfaces on a solid model is a bit more complex, however. A solid model that includes freeform surfaces can be very difficult to accurately edit in a history-free environment. Add complex blends to the model and it gets even more difficult. There are many ways to control and edit surfaces in a history-free environment, but one of the things you can’t do is to go back to the original sketches and/or curves (parent) that were used to generate the complex surfaces (child) originally, make the modifications to the curves and regenerate the surface geometry. If the tree is structured appropriately for this type of edit, the change will work well. Today it is hard to beat the benefit that a well structured parent/child relationship brings to accurate surface editing in a solid model.

So. what did I miss with regards to the benefits that come from ordered modeling features, i.e. history?

Some may want to add control for blend/round features to this list of benefits since these features are typically order dependent. In other words, depending on what order you add a blend/round, the vertex region can be different. This is true of history-based and history-free systems. In history-free the order is not available to the user to manipulate and as such getting a different vertex region may be difficult. But it can be equally difficult to reorder the features in a history-based environment, especially if you also need to add or remove edges within the feature. I am not convinced that either technology makes this very easy.

Some may want to add capturing “design intent” to this list. All four of the benefits I mention above fit into the category of “design intent”. Don’t just list design intent. Be more specific.

Some may want to add "knowing how someone created the model". But you need to be more specific than that. What benefit do you get from having this knowledge?

There is one benefit of history-based modeling that most will miss when moving to a history-free environment and that is “familiarity”. You will need to move past this one while considering this topic.

With an understanding of the unique benefits of history-based and history-free technologies, perhaps we can have a more uesful discussion on what the term “best of both” refers to in this context. When a CAD vender claims to be deliverying the best-of-both, what are they talking about?

Paul

2008 - The year of Direct Modeling?

2008-12-22T15:18:00.000-07:00

I started out this year as an independent consultant doing design and engineering work. I also did some process consulting for a few manufacturing companies, and even some consulting for some software companies as well. As an independent I was able to get exposure to a variety of different design tools, CAD and CAE. It was a good year for this as technology continued to move at a great pace.

During my time as an independent, SpaceClaim came to market (almost 2 years ago now). I had much fun with that product. They’ve done a nice job at making history-free b-rep modeling simple, fast and flexible and they continue to be a strong advocate for this direct history-free technology. They seem to be focused on a complimentary, or coexistence strategy and getting CAD into the hands of the non-experts. In 2008 SpaceClaims’ unique user interaction model and geometry interaction methodologies were “leveraged” by another CAD company, bringing further validation to their place in the industry.

Just prior to 2008, PTC acquired CoCreate, adding direct modeling to their suite of products and raising the awareness again for history-free direct, or as they call it “explicit” modeling. I watched this closely as I used to work for CoCreate. Back then PTC was of course our biggest competitor. CoCreate Modeling remains to be the most matrue and capable of the history-free direct modeling systems on the market - after all they were developing it inside of HP long before CoCreate, the company, existed.

Then came Siemens and Synchronous Technology. It was great to see all the new attention, again, on history-free modeling. The marketing buzz from Siemens was that they were the first to combine history-free modeling with a synchronous constraint solver. Although they weren’t the first, they certainly made some good progress in integrating the two technologies in a useful way. I still think they have a long ways to go to bring maturity to their history-free modeling environment and the intelligent model, but they certainly have a good start.

There were also many advances this year in direct editing within the history-based environment. Most all of the history-based CAD vendors now have this capability. It’s seems a little flakey tracking direct edits in a history tree, but it does further validate the need for more flexibility in our 3D CAD tools.

Now we have Autodesk getting into the fray with Inventor Fusion, another validation that this is where we are heading with regards to 3D CAD. I still can’t tell what this thing is though. The demos that I have seen are very trivial and simple, but they do present some nice user interaction tools and methods. So, is this a history-free CAD tool, or more direct editing within a history-based system, or some weird combo-deal? Hard to say so far. I suspect a new history-free environment that will strip away all the history and parameters of an Inventor file, similar to that of SE ST and NX6 ST. We’ll find out soon enough. They do show some nice new user interaction concepts and tools.

While I enjoyed my time as an independent consultant, this last June brought a significant change for me in that I took a job with PTC. So now I can no longer claim to be one of those “credible independent consultants”. I guess I’m now a pesky “software vendor”. It’s been a bit of a strange transition for me. Not that I haven’t always been a bit bias to history-free modeling, and specifically the CoCreate product, it’s just that now I’m supposed to be. J I still hope I can be more factual than salesy though. I think that once someone knows the facts and knows their process and user requirements they will be able to make the right alignment with technology. History-free modeling is not the answer for all design requirements. (Not yet anyway).

So what’s coming next year in the world of history-free or direct modeling? You know, now that we have a few more capable history-free tools out there, we could greatly reduce the interoperability issues that come standard with history-based tools. Models can now be fully editable across several different CAD tools. The next step is to be able to transfer history-free features, 3D annotation and parameters between these systems. The STEP protocol actually has much of this built into it already. Imagine transferring fully parameterized, intelligent, editable parts and assemblies from one CAD system to another via STEP. Could it be possible?

Merry CHRISTmas and Happy New Year!!

Paul

History-Free Bolt-Hole Pattern

2008-12-17T15:23:00.000-07:00

Here is a quick addition to my previous post about history-free parametric modeling. This is based on a question about bolt-hole patterns.

To get the video I just animated the variable that controls the outer diameter of the ring. (During the animation, only the faces that are affected are displayed) The bolt-hole radius, number of holes and the inside diameter is based on the outer diameter. As the outer diameter changes the bolt-hole radius changes as well as the number of holes and ID.

I realize this is reasonably simple stuff with a history-based system, but most people assume that it can't be done with a history-free system.

Again this is a history free model. There is no history tree and no parent/child relationships. A feature was defined from existing faces, a pattern of the feature was defined, and a few parameters and expressions were added for control. It is solved synchronously. (and yes, I did it with CoCreate)

This can be done with an IGES file.

History-Free, Parametric Modeling (Part II)

2008-12-15T09:10:00.000-07:00

In Part 1 of History-Free Parametric Modeling I attempted to present the reality of adding intelligence to a history-free model such as constraints, parameters and feature information. With Part II I hope to show what is possible with respect to assemblies. Getting a part to behave as intended (design intent) is equally important as getting an assembly to behave as intended. By capturing intelligence about the design at the assembly level, we can begin to use 3D to design products/systems/solutions rather than just parts. Using synchronous solvers on history-free part models is nothing new, nor is it new at the assembly level.

Similar types of relationships can be defined on an assembly level as on a part level. Most common may be coincidence, distance, angle, parallel and perpendicular. There also may be special assembly relationships such as gear or cam.

Again I am using CoCreate Modeling just because that is what I know the best. I am sure some of the other history-free modeling systems are capable of some of this functionality as well. The first example I will show you is of a fishing reel. A fishing reel has some reasonable mechanisms in it. While you are reeling in the line the head is spinning, and the spool is moving in and out to keep the winding on the spool even.

In this case you can see that I have several coincident relations and a gear relation. The gear relationship is used to represent the ring and pinion gear used in the reel. The rigid relations keep the subassemblies constrained as units. It took maybe 15 to 20 minutes to setup the necessary relationships for the fishing reel.

Once relationships have been defined, you can use the added intelligence to analyze motion, functions and identify interferences. In this case an animation of the solution was also captured with rendering, although my rendering is not too good. I took the cover plate off and put a mirror on the side in hopes that you can see both sides. Here is another video without the housing.

As with part relations, CoCreate Modeling allows you to have multiple relation sets on the assembly level as well. In this case you could have one set to simulate the assembly process and one set to simulate functionality. Mathematical equations are also allowed within the solution set. The equations can also include logical expressions such as if, then, else, and mathematical expressions such as equal, not equal, less than, less than or equal and others.

Here is another simple example. This one uses both a cam relationship and several gear relationships. This is the eject mechanism for a CD drive in a laptop.

Assembly relationships can be used for several purposes. They can help keep mating parts in the correct position as other parts are moved or modified. And of course they can also be used to represent mechanisms or perhaps the assembly process. Really no different than what you can do in a history-based system. The only difference is that with a history-free modeling system, the relationships can be added any time during or after the design process, and they are solved synchronously. It also seems to be a bit more intuitive and forgiving when you don’t have to be concerned with order.

I have often heard people make the mistake of assuming that by using history-free modeling you are giving up the ability to capture design intent. So I hope I have shown with these articles and simple examples that design intent can be fully captured with history-free modeling. I would even argue that it is much easier and more intuitive in a history-free environment. You certainly cannot capture how the model was created – but since when did the model creation process align with the design intent?

CAD Interoperability: Native Files vs. STEP

2008-12-10T13:57:00.000-07:00

Matt Lombard has an interesting article on his blog titled: Best way to translate Catia Files into SolidWorks? Use Inventor. It spurred a lot of good comments and questions. Check it out at: dezignstuff.com/blog/. It spurred some thoughts of my own, and now I have a related question, and it is a bit of a loaded question: Why is it important to load native files versus STEP? I think these are some of the possible answers. They may all apply, but which one best describes your need or problem?

1) Speed and convenience - no translation required
2) Managing risks - don’t want to create and manage another document of the same object
3) Must have a valid solid model - good 3D geometry
4) Must have an editable model - history tree with sketches, features and constraints
5) Must have round trip translation of editable models with no data lose

If you answered #1: Maybe this means that you have to go back to the owner of the native file to request a different format. This can create delays in the process. It should not take too long to actually create the file, but the communication and extra effort would not be necessary if you could just use the native file.

If you answered #2: If you must create a STEP file, you now have another file (document) that represents the same part. Do you know what version the STEP model is connected to? If you send a STEP model out, are you (or the receiver) confident that it is the correct version? Managing another document just adds more complexity to the process and presents a higher risk for mistakes. By using the native file risks can be lower and there is no need to manage another document.

If you answered #3: With STEP perhaps you get erroneous data/geometry – missing faces, gaps, and other geometry problems. You assume that by loading a native file you will get better geometry translations. This assumption is probably wrong, however. There are several issues. If the sending system is a history-based system, the native file may not even contain the 3D geometry, but rather only the receipt, or history-tree, with sketches, feature definitions and parameters (another issue covered later). If the native file does contain geometry, the resolution or accuracy of the geometry will be based on the CAD systems operating model resolution. For some strange reason all CAD vendors have chosen different model resolutions for their CAD system to run at. For some it is adjustable, for others it is somewhat dynamic. Translating a model from a high-res CAD system to a low-res CAD system is not a problem. Going from low-res to high-res is a huge problem. Do you know what model accuracy your CAD system is using when creating 3D geometry? Solid Modeling is all about connectivity. If it cannot connect, it is not a valid solid. The big problem with this geometry accuracy issue is that the people that are creating low-res geometry probably don’t know it. It’s the ones on the receiving side that know it – unfortunately they usually blame the problem on their own CAD tool, when in fact the geometry issues are most likely a result of the junk data coming from the sending system.

If you answered #4: If the sending and/or receiving side of the exchange is a history-based system and you need editable models, you must have the history-tree with all of its components. This is a very tall order. The technology to translate one history-tree to another exists but it is very complicated and expensive. Basically the history-tree, and its contents contain a CAD systems competitive advantages. Things like a special modeling feature or perhaps a unique rounding feature are all contained in the tree. A new version of a CAD system will certainly have enhancements and new features that are captured in the tree. What if one of these features (competitive advantages) does not exist in the receiving history-based CAD system? How will the receiving system handle it? What happens when you upgrade to the next latest and greatest version?

If you answered #5: Go out and purchase a history-free CAD system, now. If this is a requirement and you don’t have one, you are wasting HUGE amounts of money and time. (and/or putting reducilulous requirements on your suppliers.) Just make sure your suppliers are deliverying good high accuracy geometry. Set some standards for it - after all you are paying for it.

So the next time you have a discussion with your CAD vender about interoperability and data exchange, don’t just tell them that you need to load native files, tell them what it is that you really need in order to support your processes and requirements - describe the problem. Too often we tell them how to solve a problem rather than telling them what the problem is that needs to be solved. They are actually good at solving problems, once they know what the REAL problem is. (Also, while you are at it, help your CAD supplier understand your need for higher resolution/accuracy geometry. I am continually amazed at how much junk geometry comes out of our modern CAD systems.)

Paul

Getting Expected Results with Direct Editing

2008-12-04T11:09:00.000-07:00

I received a few questions about an earlier article with regards to getting expected results from direct geometry edits. When you start pulling on various faces of your model you may or may not get what you are expecting. This applies to both history-free direct edits as well as history-based direct edits. To show this in its simplest form I will use the simple model shown below. In this case we are pulling on the yellow face.

With a linear pull there are at least four different possible solutions to this edit.

#1 - The pull face changes size as the adjacent faces are stretched
#2 - The pull face size is maintained, the adjacent faces are stretched and the angle of the top face is changed, topology is unchanged
#3 - The pull face size is maintained, the angle of the top face is unchanged and topology is changed – a new face is created
#4 - The pull face changes from a planar face to a b-spline surface

There are certainly other possible results if you pull around an axis.

With history-free modeling there may not be any relationships or conditions built into the model that would drive any one particular result. As such the results are completely based on the type of command or command options that may be available to the user.

For direct edits in a history-based system, the result may be completely dependent on how the model was originally created, as with any other edit in a history-based system.

In the history-free category, with their instantaneous graphical feedback, SpaceClaim certainly leads the way in helping the user understand the results immediately. I just personally struggle in SpaceClaim finding the right options to get different results, but I’m no expert with SpaceClaim.

Siemens is following SpaceClaim with the instant feedback, but again getting different results seems difficult for me. #1 and #3 are easy to get with the Pull Face or Move Face commands. The others???

CoCreate Modeling provides all the options for getting any of the results above, but it does not yet have the instant graphical feedback for case #1 and #2, although I am sure this is quickly changing.

As with any CAD tool, it takes some practice to understand what is possible and how it’s going to work, but don’t assume that just because it is or is not possible in one system, that it will work the same in others. There's a lot of progress being made in direct editing technology. The nice thing about history-free direct edits is that the results are completely independent of the how the model was originally created. You decide, right at the time of the edit, what results you need and “make it so”.

Paul

History-Free, Parametric Modeling

2008-12-01T07:26:00.000-07:00

History-Free parametric modeling? Is there such a thing? To some it may sound like a contradiction in terms. The term “Parametric Modeling” is often used to describe history-based modeling. Certainly parametric modeling came of age within the context of history-based modeling, but in fact, parametric modeling is not reserved for the history-based CAD products.

For me “parametric modeling” simply refers to the addition of persistent geometric relationships, constraints and parameters to 3D models. This added “intelligence” is then used to control the behavior of a model. The following are some common examples of relationships, constraints and parameters:

Parallel
Perpendicular
Tangent
Coincident
Planar
Distance
Angle
Radius
Diameter

History-based modeling provides a nice platform for parametric modeling in that you can easily add parameters to the 2D sketch. It is also common to have predefined parameters and constraints associated with 3D modeling features, such as the depth and diameter of a hole feature. During the creation of these features, users are given the opportunity to specify the value of the parameters. Once the sketch is defined and/or the modeling features are defined, they are captured in the history tree. Users are also given the option to add dimensional parameters to the sketch and/or modeling features. When changes are needed, a parameter or constraint can be adjusted and the history tree will be replayed to form a different model based on the modified parameters. The model is actually recreated from the point of change each time the tree is replayed, or regenerated. The parameters are similar to variables in a software program. Change the variables and replay the program to get different results.

Parameters and constraints in a history-free environment can be a bit more complex in that they are all 3D and must be solved synchronously. They must control conditions in 3D space that are typically controlled in 2D space within the history-based 2D sketch, such as tangent or parallel. Due to these complexities, the history-based platform may be the ideal platform for fully constraining a 3D model. However this is quickly changing with continued advancements in 3D parametric solvers and new intuitive methods for applying and interacting with 3D parameters.

Today there are only a handful of history-free modeling systems on the market, and only a few of those have full parametric capabilities. PTC CoCreate Modeling (Formerly HP SolidDesigner) has had this capability for many years now and probably has the fullest set of capabilities for managing 3D parameters within history-free geometry. As such I will use examples from CoCreate Modeling to highlight some of the challenges and benefits of history-free parametric modeling.

One of the key benefits of history-free parametric modeling comes from the fact that these parameters can be defined anytime during or after model creation. Parameters can be added and removed anytime regardless of the completeness of the model. As a matter of fact, an imported IGES or STEP file can be fully constrained and parameterized with a tool like CoCreate Modeling.

Below is a picture of a wheel that has been constrained using CoCreate Modeling. It is probably not fully constrained, but may be close. This wheel started out as an IGES file from some other CAD system, so all parameters were added after the fact. In this case there are basically three key variables identified in the solution. One for controlling the width, another to control the outer diameter, and another to control the bolt hole circle radius. The parameters are organized and managed in what is referred to as a “Relation Set”. Relation sets are owned by the part. In the picture of the Structure Browser you can see a part called “Wheel”. Underneath Wheel is a relation set called “Wheel_Set1”. Within the set is the list of all the parameters that have been assigned to the part. The first parameter in the list is a Radius parameter that is the driving parameter for controlling the outer radius of the wheel.

With a parameter set like this, it takes CoCreate Modeling maybe 12 seconds to solve the complete wheel when a change is made. It will not make a difference whether one variable is changed or all three are changed. It takes the same amount of time to solve, as you are solving the entire solution set simultaneously.

To reduce the amount of time it takes to solve a set, CoCreate Modeling allows you to have multiple relation sets per part; any number of sets with no limit. However, only one set can be active at a time. Multiple relation sets also gives you the opportunity to capture multiple studies or scenarios within one part. Something that is not possible with history-based modeling without building a new part. In the example below, I separated the parameters into 3 different sets. One set to control the width of the wheel, one set to control the outer diameter, and one to control the bolt hole circle. Each set is now independent and will not impact the other. In this case now, to solve for example a width change, the solution will take about 5 seconds to complete. (Of course this depends on the machine you are using). The change has no impact on the other relation sets. Notice how all other geometric conditions are being maintained within the model, conditions such as tangent and concentric.

You can also include equations into your parameter definitions. For example in the Wheel_Width set there is a simple equation that will drive the location of the hub based on the width. If you look closely from image one to image two you will see that the position of the hub changed relative to the front of the rim, as the width changed. The equations can also include many logical expressions such as if, then, else, and mathematical expressions such as equal, not equal, less than, less than or equal and others.

Here is another simple example of a history-free parametric model. In this case it is a plastic connector body. There are a few features and patterns that have been defined. Parameters are then used to define the number and placement of the features. One of the parameters is used to define the number of pins for this connector. Based on that number, features are added or removed and the geometry is adjusted.

As with any parametric modeling tool, it is possible to over constraining a part. If this situation happens in CoCreate Modeling the system will highlight the parameters that are involved with the over constrained condition to help the user quickly resolve the situation.

Parameters are only as good as the underlying geometry engine is at making the actual geometrical change. If the system is not capable of making complex geometrical changes, driving that same change with a parameter will also not work. As mentioned in an earlier blog article titled “Key Capabilities of History-Free Modeling”, properly managing adjacent faces and topology changes are critical to history-free modeling.

Of course adding parameters to a model is only good for one thing; controlling the behavior of the model. This type of control is not always necessary however. With history-free modeling you have complete flexibility in adding constraints and parameters to your model. Users can focus on the task of design, and only apply parameters and constraints where and when it makes sense and adds value. Keep it “Lean”. Don’t waste time on creating data that adds no value to the actual design.

So, history-free parametric modeling is a reality and it is VERY cool. It actually works like most engineers think – unless they have been brain-washed with history-based modeling. History-free parametric assembly modeling is also a reality. Maybe I will cover that topic in a later blog.

Paul

3D Solid Modeling Terms & Definitions

2008-11-12T17:29:00.000-07:00

(according to me)

It’s amazing how many different terms are used to describe the same thing, especially as it relates to 3D modeling and the related technologies. So here is my take at a few of these. Please add your own, or suggest corrections to mine.

History Based Modeling: This is the typical technology used for most of today’s 3D CAD systems. Modeling operations are stored as features and organized sequentially in a tree, maintaining a parent/child relationship. As you are creating the model a recipe, or program, is being created that will record everything about the development of the model including 2D sketches, 2D parameters on the sketch, 3D operations and the parameters, or variables, related to the 3D operation. Edits are done by accessing one of the previous operations and adjusting a sketch or a parameter. After adjustments are made, the “program” can be replayed to get a different or edited model.

Other terms for history-based modeling:

Parametric Modeling: This term is used as parameters are critical to the ability to make edits to a history-based model.
Variation Modeling: This is an old term that used to be used to describe history-based modeling, but in this case the sketches and 3D operations did not need to be fully constrained. You don’t hear this term used much anymore.
Others: ?

Other related terms:

Direct Editing: This term is usually used to describe direct geometry edits that are being done within a history-based environment. Each edit is usually captured in the history tree, similar to a feature. There are some exceptions to this.
Others: ?

History-Free Modeling: This term describes a method of creating and editing 3D geometry by directly interacting with the geometry. Modeling steps, or operations, are not stored and there are no parent child relationships. Edits are not done through interaction with previously defined features or sketches. Edits are performed directly to the geometry. These CAD systems must be very intelligent to properly and intuitively manage geometry and topology of a solid model. If editing of any geometry attempts to create a hole or gap in the solid, the solid can be corrupted and the operation will fail. If topology (connectivity) must change to support a desired edit, the system must make intelligent choices and properly reconnect the solid.
Other terms for history-free modeling:

Explicit Modeling: PTC. This term takes me back many years. In reality, before there was history-based modeling there was only Explicit Modeling or CSG Modeling. Those were your choices. Today’s history-free modeling is a long ways from what it was back then.
Dynamic Modeling: CoCreate (before PTC)
Direct Modeling: Not sure where this came from
Natural Modeling: I’ve seen SpaceClaim use this term
Synchronous Technology: Siemens uses this term
Geometry-Based: Kubotek uses this term occassionally
Others: ?

Here is another way to describe the two.

History-Based Modeling: A dumb CAD system interacting with an intelligent model (Sounds a little harsh, but in reality you are just writing a program graphically and defining variables, changing variables and replaying the program. The history-tree is the program, the CAD system is the compiler and the model is the output.)

History-Free Modeling: An intelligent CAD system interacting with a dumb model (although the model can be made intelligent, it is not required)

A Day in the Life of a Frustrated CAD User

2008-11-04T07:24:00.000-07:00

This letter is about 8 years old. I just found it as I was going through some old files. Not sure why I kept it around other than for a few good laughs. Not sure why I'm even posting it. I did take the name of the CAD system out of the letter as he doesn't speak to highly of it. (I also tried to clean up the expletives)

-----

>> So how is everything going at your new company? How is the CAD system?

I spent 12 hours today changing 1 note on 4 drawings, making .igs and .pkg files. Every time I turn around, something updated and created massive data management nightmares. Another thing I can't stand is that your model file automatically saves every time you check something out, check something in, move to the drafting setup, move out of the drafting setup. I ---- you not, if you have a decent size model file, you can easily blow 10 minutes per hour waiting for ---- while it is saving. And anytime you have to ---- around with the history tree, you have to update the part. Well, nobody gives a ---- (and I don't blame them) about how gigantic a history tree is. So guess what, if you are trying to change a feature and it ----s up something downstream, you spend 80% of your day trying to get the part to update. Don't forget the automatic save, so no going back. If you ---- up a tree, you get to either blow the whole day, sometimes more just trying to get it back to where it will update. Modeling in solids is almost impossible. So instead of actually designing, you spend 90% of your time in the history tree, hunting down bad nodes, then when you find them, it's a complete mystery how they happened, and how to fix them. Nobody constrains anything (again I don't blame them) so there goes the POWER OF this CAD System right down the ol porcelain hopper. The only people enamored with this CAD System are the CAD Admin guys, and the managers who don't have to use it. It is such a bogus tool.

Get this: A set of 4 bezels. Basically a hollow injection-molded shell with 4 bosses. Rates a 2 on a scale of 1 to 10 in difficulty. Since this program was rolling before I got here, the job was outsourced. This firm had 3D imported models that were of pressure-formed design. All they had to do was convert the design from CAD SystemA pressure-formed parts to this CAD System injection-molded parts. If I were using SolidDesigner, this job would have not taken more than 1 month at the most, including 2D CPK drawing. I think the parts could have been modeled in maybe 6 days tops. Took these guys 3 MONTHS and $25,000 dollars. We have 3 guys who are CAD System experts, and you would not believe how many times they have told me, "It's going to be easier if you just recreate the model". ARE YOU ------- KIDDING ME? These outsource 'experts' have actually asked me, "How important is it for THAT change to happen? It's really going to take some effort”. This was the response to my request of, "Can you make the boss .10" taller?". EXPERTS! How ------- embarrassing. One bezel would not update because of a blend that was ----ing up an edge. Took 2 guys, 6 hours working on it, and they finally said, "eh, we couldn't get it to work, you'll just have to live with the messed up history tree." A---------MAZING.

My "mentor" just keeps laughing, because he's a SolidDesigner user, so he knows the nightmare we are living. And PCB assemblies? We get a 2d .dxf file we can overlay, and model up the components ourselves. We have to track down the data sheets, model capacitors, asics, ---- like that. Modeling electronic components! What the ----! It would be a cakewalk for 3 SolidDesigner guys to blow 6 CAD System guys out of the ------- water. I'm getting really close to modeling my parts in SolidDesigner and then exporting them to CAD System as an .igs file. So what if the history tree is non-existent? Can't use it if it's there. I personally don't even think anyone would know what the hell I was using! This one poor bastard, he goes, "I like the history tree, you can go back and see how somebody modeled the part, and put in a feature before another feature, yada yada yada..." I said who gives a fat flying ---- about how somebody else modeled the part. I just want to punch a hole, delete a blend and be done with it. I'm here to design, not to do autopsies on parts that take longer than it took to design the entire product. Get this: I've only designed 1 part in the 3 months I have been here. And this company is ok with that. Freaky!

I talked to my buddy that is running SolidDesigner2000 on NT about how much CAD admin it requires. They don't even have a CAD admin guy. Freaky! We got CAD admin guys that used to work at CAD System that tell me, "oh, no... you can't do that." "It’ll be easier to recreate the part." "Do you really need to add a radius in that corner?" And they are all excited about the new version! oooohhhh....The new Yugo is out! The new Yugo is out!

Actually, this CAD System is like having an Italian sports car: REALLY powerful, but you have to crawl in traffic all day long. Goes really fast....when it works, you're actually fixing it 90% of the time. Want to change something, like valve caps on your tires? That would mean you have to change your valve stems, then change your rims, then your tires, then your braking system, then your engine. You know what? It would just be easier if you go get another car. It would be a lot easier. So give me a call sometime, and be happy with your CAD system.... I miss those days...."

------

Well, fortunately CAD systems have improved a lot since then. I don't think this happens anymore.

- - - does it?

Paul

Key Capabilities of History-Free Modeling

2008-10-27T17:26:00.000-06:00

Whether it is Dynamic Modeling, Explicit Modeling, Direct Modeling, Synchronous Technology, Natural Modeling, it all refers to history-free modeling. There are only a handful of companies that have developed usable history-free modeling and all of them have claimed to be the first to do it. They're all wrong. History-free modeling actually existed in the very early days of CAD in products like Anvil, Graphtec, ME30 and Unigraphics to name a few. Back then it was called Explicit, or Boolean based or B-rep modeling. The systems were robust but also slow and inflexible. When history-based modeling hit the market with Pro/E, we were all amazed and most never looked back - until now.

I started out thinking I was going to write up a comparison document between some of the history-free modeling technology out there. But maybe it would be better just to review what some of the key capabilities are of history-free modeling so that you can do your own evaluation.

Actually some of you may be asking questions like: Why should we even care about history-free modeling? What’s wrong with history-based modeling? We’ve been using it for about two decades now. Here are a few reasons why history-free modeling is gaining popularity:

Interoperability:

Team members do not need to understand the modeling history
Imported data does not include modeling history

Flexibility:

No need to be concerned about how you model a part – focus on design, not modeling
No need to understand how a part was modeled.

Lean:

Much easier to learn and use.
Some are starting to realize that the extra effort involved with history-based modeling does not justify the value, (very process and product dependant) and are looking for an alternative.

Technology:

Computer power and technology has now evolved to make history-free modeling a viable alternative to history-based modeling.
Robust and mature technology exists that allows for the capture of design intent directly in geometry rather than through the modeling history.

There is certainly a lot more to a good CAD system than creating and editing geometry, but this is a good place to start with an evaluation.

With history-based modeling, the methods for geometry creation are fairly well defined. Typically geometry is created with sketches and 3D operations and by adding features such as holes, cuts and filets. CAD companies continue to make this process more intuitive and capable, but in general there are limitations based on the fact that each modeling operation must be maintained and ordered in the tree. With history-based modeling you are either creating features or modifying features. With history-free modeling, the line between creation and modification becomes very blurry.

With history-free modeling, developers have a much more flexible environment to work with. There are really no limits to geometry creation methods and processes. In modern history-free systems a sketcher may be used very rarely. You may start with a sketch to get some quick geometry in place. But from that point on the modeling process will be made up of a mix of feature creation and direct geometry manipulation.

As you look at the capabilities of history-free modeling, you certainly need to look at the capabilities of the sketcher and the other methods for creating different types of geometrical features. However, direct geometry manipulation is the key to history-free modeling. When looking at direct geometry manipulation, there are three primary areas that must be considered:

Geometry Selection
Transformation Definition
Predictable Results
- Adjacent faces
- Topology changes
- Design intent

With history-based modeling, the first two are determined by the process that was used to create the model in the first place. The last one is only possible, if you thoroughly understand the model creation history, AND, if the model was created in such a way to support the needed edit.

With history-free modeling the system needs to provide intuitive methods for:

Selection of geometry and perhaps automatic selection of geometry depending on geometrical characteristics, such as pockets and bosses.
Intuitive methods for defining transformations in 3D space. This can be done with parameters and dimensions, it can also be accomplished with some useful tools for defining 3D directions and axis.
Once the geometry is selected and the transformation is defined, the system then needs to intelligently make the change. There are usually multiple solutions from a geometric point of view, but getting the expected and most logical result is what's important.

Pay close attention to these 3 things when looking at history-free technology. Here is a look at the three in more detail.

Geometry Selection
Most geometry edits involve a face or a group of faces depending on what you are trying to do. Here are some possible face selection methods.

Single
Multi-select
All
Pocket
Boss
Rib
Slot
Adjacent
Tangent
Chain
Viewport box
3D box
By color

Some of the above methods require much intelligence in the system to interrogate geometry to determine resulting selections. Pay close attention to the results. These selection methods should work on imported geometry as well as native geometry.

Transformation Definition
Once you have selected the geometry that you want to edit, you will need to specify how the geometry will change. Positioning geometry in 3D space is nothing new, but in this case we are positioning a face or collection of faces in 3D space. Again with history-based modeling the possible transformation is determined at the time the model is created. History-free modeling has to provide much more capability in its methods of defining 3D transformations. Here are a few of the common methods.

3D direction and distance
3D axis and angle
Point to point
Radial
Mate
Align
Match points (3 points to 3 points)
Dimension (linear or angle)

There are a variety of ways that CAD companies have come up with to help with the process of defining 3D transformations. Some of the methods include 3D icons that represent 3D direction vectors and 3D axis. Others allow the use of existing 3D geometry to specify points, vectors and axis. Other coordinate systems can be used as well.

Also some systems allow the combination of the methods listed above into one command to make the transformation quicker and more intuitive.

Look closely at the tools and methods provided to define 3D transformations on a face level.

Predictable Results:

> Adjacent Faces
One critical aspect of a predictable change is in what happens to the adjacent faces when a face, or collection of faces, is moved. Edits usually require adjacent faces to be stretched, shrunk or adjusted in some way, and it should be fairly intuitive. In the images below we see a simple diameter change of a hole. The next change involved two faces moved, and in the last example a collection of faces are selected and moved. In all 3 cases, the changes are very simple in that there was no change to the structure, or “topology” of the model. The edits only required that adjacent faces adjust.

Where it gets challenging is when the adjacent faces are blends (filets or rounds). Some systems can recognize faces as blends, while others can’t. In history-free modeling it is common for the system to attach an attribute to a blend face so that the system knows it is a blend. If so, the result should be that of the second image below. If not, the result could be that of the third image or perhaps failure. The real test is to try this on an imported STEP model to see if the system can still recognize the blends.

This is a very simple example. You really need to look at more typical situations you may find in your own parts.

> Topology Changes
When you start tugging and pulling on the faces of a history-free model there is a high likelihood that you will force a change in topology. “Topology” describes how a b-rep solid model is connected. Points are connected with edges. Edges connect to form faces, and faces connect to form a solid. A b-rep solid is all about connectivity. The big question is; how is the system going to handle topology changes? Of course the best way to find out is to try it. Select a face or two, specify a logical transformation forcing faces to run into other faces, and see what happens. Maybe an easy test is to move a boss, pocket or hole from one face onto another face.

Here is a simple example of a topology change in a history-free model. In this case a boss was automatically selected, and then a transformation was defined (one picture shows a point-to-point transformation, the other is a direction and distance, and the last is a combination of a direction and distance with a rotation). You can see the results of each, and in all three cases the topology of the model is changed.

> Design Intent
Another thing to consider with history-free modeling is the design intent of a model. In this case I am only referring to intent at the geometry level, not the assembly level. At the geometry level there are several types of relationships than can be captured such as:

Tangent
Coincident
Coaxial
Symmetric
Parallel
Perpendicular
Distance
Angle

Take a look at what capabilities the system has for adding this type of information into the model. In some cases it may be automatic. There also may be flexibility to turn the conditions on or off during modification. Then look at how modifications work when these conditions are active.

The technology behind history-free modeling is moving ahead at an amazing pace. It is likely that sometime in the very near future you may wonder what value a history tree provides.

Paul

Synchronous Technology and My First Impressions

2008-10-17T08:51:00.000-06:00

I finally got my hands on NX6 and have been able to try this so-called breakthrough in CAD technology that Siemens calls Synchronous Technology.

I first got myself back up to speed by using NX6 in its default history-based mode. And as with any history-based modeling system, it is a painful process making sure that the tree is structured properly and constrained in a useful and predictable way. And as usual once you do have a nice model created that behaves the way you want, you feel gratified. Kind of like when I solved the Rubix Cube for the first time. Highly constrained and structured models certainly have their place in product development, but conceptual design is not one of those places. And just hope that you do not have a sudden change come to you once you have this nice and highly constrained model completed.

With NX6, like many other history-based systems you do have the option to perform direct edits on geometry. This capability is provided to allow you to accommodate small unforeseen changes that may come at you without having to mess with the tree or parameters. Unfortunately these direct edits are captured in the tree so that the next time you have to regenerate the model, the changes are not lost. The end result is an even more complex and volatile tree.

So to work around all the usual issues of using a history-based system for concept design, rapid design cycles, interoperability, and so on, Siemens has introduced Synchronous Technology, which will save us all from this misery.

Siemens has claimed to introduce the next breakthrough in 3D CAD with what they are calling “Synchronous Technology”. The demos that are out there look reasonable good, as any demo should. The use model looks nice and the graphical interaction and feedback appears to be very nice.

On the contrary though, what Siemens has introduced, was in reality introduced 10 years ago when Hewlett Packard first imbedded the synchronous parametric solver from D-Cube into their product – SolidDesigner. Since then the product was moved out of HP into CoCreate, and is now part of the PTC product line. The product is now called PTC CoCreate Modeling. Siemens’ Synchronous Technology is simply a combination of history-free modeling with the D-Cube synchronous parametric solver. Exactly the same as what HP did in the late 90’s. The D-Cube solver delivers synchronous solutions to geometrical relationships like dimensional parameters, coplanar faces, concentric faces, tangent faces, parallel faces, perpendicular faces, symmetry and coincidence. This capability allows an explicit – or “history-free” modeling system to apply needed relationships/parameters to 3D points, edges, faces, features, parts and assemblies. The relationships are solved synchronously and simultaneously. It is a mature and robust technology.

There are so many terms that we are hearing and using in so many different ways, that it causes much confusion. I think marketing departments purposely try to do this to keep us in the dark. The term “parametric modeling” usually refers to history-based modeling. The problem with using this term to describe history based modeling, is that it implies that explicit modeling can’t be parametric, which is completely untrue. Fully constrained models and assemblies in a history-free environment is possible. The difference between managing parameters in a history tree versus a history-free environment is that with the history tree, parameters are solved linearly as the tree is regenerated. In a history-free environment the parameters are solved simultaneously or “synchronously”.

Another term that gets abused is “direct editing”. In most cases this describes the capability to make direct edits to geometry while in a history-based environment, as discussed above. These direct edits are capture in the history tree. They must be maintained in the tree otherwise a model regeneration would remove the edits. Don’t confuse “direct editing” with explicit modeling. They are two different things. Explicit modeling is simply modeling without a parent-child relationship (history tree).

I am a long time user of CoCreate Modeling and am now getting some good experience with ST (although no formal training). Explicit modeling requires much intelligence in the modeling system to manage connectivity with the model (topology). It can be very complex. CoCreate has spent many years on this technology to ensure that results of edits are intuitive and expected and that the model remains a solid. CoCreate is very robust and easily handles complex topology changes in the model. It also properly manages adjacent faces, blends and chamfers, even on imported geometry. On the other hand ST is VERY immature in this area. Very rarely are edits that require topology changes successful. It has no concept of recognizing blends and chamfers. It does understand tangency, coplanar, parallel and similar conditions, but again rarely does that deliver the required results. It does recognize bosses and pockets, but has a lot of limitations even with this.

ST simply does not provide enough capabilities (yet) to justify sacrificing your history tree. Just use the direct edits that are already available.

For companies that can use the flexibility that comes from explicit modeling, CoCreate is still the best choice. The choice should not be based on user preference either. The parent/child relationship is not optional with history-based modeling and it has huge impact on process. I can’t tell you how many companies I have visited over the years that have developed huge manuals to define modeling standards for their users to follow in order to structure history trees in ways that will allow for team design, leverage and reuse and predictability in the model. For some companies this is required. For others, once they understand explicit modeling, they will realize what a waste of time and effort managing a history tree is.

I am currently going through a comparison of ST with CoCreate and will post my results when complete.

Moving from 2D to 3D to Digital Product Development

2008-09-16T14:58:00.000-06:00

Realizing the continued advances in computer technology and 3D CAD, it is a bit odd to consider that even today much product design is still being done in 2D. AutoCAD from Autodesk is still a top seller within the product development space. Autodesk touts many thousands of seats on support within the mechanical space. Why hasn’t everyone switch to 3D design by now? Students are now leaving high-school and college with 3D CAD experience. The software is considerably lower cost and is now much more capable and useable. So why is 2D still being used for mechanical design?

Of course the question is not that simple. Let’s first take a look at the usual transition from 2D design to 3D product development.

Design with paper and pencil, create detail drawings on paper
Design with paper and pencil, create detail drawings with 2D CAD
Design with 2D CAD, create drawings with 2D CAD
Create 3D models, use 3D models to create 2D drawings
Design in 3D, use 3D to create 2D drawings
Design in 3D, virtual prototype and simulate in 3D, use 3D to create 2D drawings
Digital product development, leverage 3D throughout product lifecycle to reduce/eliminate the need for 2D drawings and duplicated effort

Today product development is being done at all levels listed above, from level 1 to level 7. As strange as it may seem to some of us, products are still being designed with paper and pencil. Equally strange, for some of us, some product development is being done with little or even no drawings. For those companies that have actually made it to level 7, the success that they are having would indicate that eventually, if you want to compete in product development, 3D will be a key component of your product development processes and environment. So what’s the hold up?

2D has been used for design ever since man started designing things thousands of years ago. It was only recently that we started using computers to assist with the design process. Moving from the drafting board to CAD took some time to get used to but it was not a difficult move once we gained confidence with the computers. Moving to the computer did not involve any change in the process other than we were plotting our drawings rather than blue printing them. The actual design process changed very little.

When 3D first emerged into engineering and product development, it was very expensive and slow. A few early adopters were able to get value from it, but 2D CAD was still the tool of choice for real design work, besides our processes were very dependent on the 2D drawing. While some understood the benefit of designing products in 3D, most systems were justified and purchased on the idea that 3D would provide the ability to speed the process of creating drawings. At this stage many companies made the decision that their products were so simple, from a geometrical view, that 3D would not provide the needed ROI. I have personally been told by several company representatives that their products are so simple that there is really no value for them to move to 3D. Generating the necessary 2D drawings is most likely not the bottle-neck of the overall process for these companies. But are there other benefits to 3D that these companies are missing out on?

There are many companies still with this mindset. They have made the conclusion that the value of moving to 3D does not justify the cost. Obviously these are the two areas we will focus on in this paper. What is the benefit and value of 3D based product development environment, and what is the cost of moving from 2D to 3D? Considering that 3D CAD has now existed for at least 30 years, we should be able to answer these questions.

Using 3D to create Drawings Faster

Benefits:
While some may argue, it is very easy to prove with most any 3D CAD system that you can create drawings faster with 3D than with 2D. Even a drawing for a simple shaft can be created faster in 3D than in 2D. The 3D user simply creates the profile of the shaft and revolves it. You probably need at least 2 views for the 2D drawing. In 3D, these views are created automatically and match exactly. By the time the 2D draftsman has the first view done; the 3D user will have the entire drawing completed, along with a nice 3D representation of the shaft that can be leveraged into the assembly design process, and perhaps other future products. Creating drawings faster represents the most minimal benefit /value of moving to 3D. To understand this value you simply need a stop watch and an understanding of the hourly rate/cost of a draftsperson.

Costs:
Moving to 3D to create drawings faster does not require a process change. You will need to purchase a 3D CAD tool, but most of the cost will be related to the training required of your CAD users on a new system. There may also be some cost related to the management of 3D models and associated drawings. When selecting a 3D CAD system at this stage we usually consider functionality and ease-of-use as critical criteria. These are important factors, but take note that there are many differences in today’s 3D CAD products that can have significant impact to your design process. It may be wise to get some professional help to ensure that you are putting in to place the right foundation that properly supports your process and business needs. Making the right choices at this stage can greatly reduce the potential for future cost as you mature in the use of 3D design data.

Another cost that may need to be considered at this stage is related to your existing design data. In some cases this may be in the form of paper drawings, but more often today this data is in electronic form. The value of this data is usually aligned with the lifecycle of your products and your requirement for leverage and reuse. Typically companies will maintain this data in its current form, which means that the costs related to maintaining (viewing, changing, printing, storing, …) will not go away just because you purchased a new 3D CAD system. These costs will remain for some time, perhaps years. There can be much value, however, in leveraging 2D data into 3D on an as needed basis. If leverage and re-use is important to your business, be careful in the selection of the 3D system to ensure that the provided functionality to leverage and reuse 2D data fits your process requirements.

The 2D Environment

Using 3D to create Accurate Drawings

Benefits:
This represents a much more substantial value than just making drawings faster. With one 3D model, many views of the part can be generated, across sheets if needed. All views will match the model – exactly. There is no possibility that one view is incorrect. An incorrect drawing that goes to production can have substantial costs. At this point drawings are still the master document, but they are entirely derived from the 3D model. To understand the value you will need to evaluate the frequency of errors related to incorrect drawings, and the cost related to the error.

Costs:
Creating more accurate drawings by utilizing the 3D model is a given, and will require no additional investment, other than perhaps continued education in the use of the tool. As users become more proficient in the use of 3D, 2D views in the drawing are just simple output from the 3D model. It is now just a matter of annotating the views.

The 3D Environment

Using 3D to create Accurate Designs

Benefits:
Now we are approaching a level of value that is not only substantial but also somewhat difficult to measure. In the first two situations mentioned above we are assuming that drawings are being created of good designs. In this case, we are questioning the accuracy of the design itself. Do parts fit together correctly? Are interferences understood? Does the assembly work as it should? At this point drawings may still be the master document, but the 3D model is being used deeper in the design process to ensure accurate designs. We can also begin to formally manage the 3D model and assemblies. BOM’s can be extracted and access controls as well as revision and versioning can now begin to be applied at a part and assembly level rather than just documents and drawings. To understand the value, look in the scrap bins of your manufactures and assembly lines. Also understand the volume of change orders and why they occur. How much rework is being done due to errors in the design of the product?

Costs:
At this stage there may be some impact to process, although minimal. What can be more of an issue, and cost, are the necessary changes to culture and habits that will be required of the CAD user. Some of this will happen naturally as they grow in the use of 3D. Further training for the CAD user will also be required to take advantage of more of the advanced functionality of the CAD system. Assembly modeling will now be required. Standard part libraries should also be developed and maintained to get full advantage of the system. There may be additional design task specific modules that may need to be purchased. Also at this point, more formal management of the 3D models and assemblies will be required. Without formal management, wasted duplication will occur. Part naming and numbering at the model level will also be required and, if not already done, will require much attention. Drawing numbers will begin to lose their relevance.

Using 3D to support Digital Product Development

Benefits:
As we leverage 3D to support and now drive complete digital product development, value can be a magnitude beyond that of creating accurate designs. It can also be even more difficult to measure, but it is possible. What we can begin to consider at this stage is the leverage of 3D data throughout the product development lifecycle. We can now consider the 3D model as the master, rather than the 2D drawings. All downstream documentation is derived from the master model. Rapid prototyping can be completed based on the master model. Manufacturing and assembly tooling can now be derived from the master model. CNC programs can also be developed based on the 3D model geometry. The effort to develop and maintain fully detailed drawings can be greatly reduced and in many cases eliminated. With the 3D model as the master, the management of information can be greatly streamlined. With formal management of the master model and all related information, everyone will be working on the latest version. Team members are informed of all changes as the development progresses.

Costs:
As you move to digital product development, process change will be the most significant cost. With process change comes some need to address culture and habits as well. This will also require close interaction with downstream processes, including the supply chain and partners. There may also be additional functionality that will need to be purchased to get to this level. Another significant cost will be PLM. Formal product lifecycle management must be in place to support this level of productivity. It will not work without it. Unfortunately the costs to move to this level can be very elusive. It is greatly dependant on the product design cycle, product lifecycle, product volumes, supply chain, company size and distribution, and key business drivers. Don’t just start throwing tools and technologies in assuming that what works for one company will work for ours. Pay close attention to business drivers and the supporting processes. Otherwise your costs will go quickly out of control – very fast and very big.

Summary

At a very high level, the value of 3D can be summed up very quickly. Basically as we work through the various stages identified above, we are simply reducing the potential for duplication of effort, and accompanying error. We are also increasing our ability to leverage existing data downstream, resulting in improved innovation, higher quality and reduced cycle times (to name a few). Sounds a little too simple, but basically that is what it is all about. Consider designing in 2D, if you are designing a part with a hole in it, it is very likely that you are creating a representation of that same hole several times as additional views are added. This is a simple example of where duplication of effort can be eliminated as you progress into 3D design. Consider a tool designer that is using 2D to design the required tooling, if the 3D model is not being leveraged; geometry is certainly being recreated that has already been created at some point earlier in the process. It is very easy to consider countless other possible ways that duplication of effort happens within product development and throughout the product lifecycle. The basic value of 3D is in doing something once and leveraging it to the maximum possible.Consider cost, also at a high level. What must be considered foremost are culture, process and business. In reality the purchase of a 3D CAD tool may be the lowest cost piece of the puzzle. Tools and technologies, including 3D CAD, must enable process and process must deliver on business drivers and objectives. If you start throwing tools and technologies into the mix without considering this, costs can quickly fly out of control. It is important that you start with the right tools and technologies that support your business and process drivers and requirements. As progress is made in the use of 3D, process will need to adjust. However the impact to process can be minimized by selecting the appropriate 3D technology/tool. Often times 3D CAD is purchased based on user preference, ease-of-use or other low-level requirements. Be careful, there are many differences in today’s 3D CAD systems that can have significant impact to process. Select the right tools in support of your business needs.

Take a close look at the state of your product development process. Where do you fit on the chart above? Can you recognize the value and benefit of moving up the chart with your processes? Are the related costs understood?

The chart above from the Aberdeen Group indicates that those companies that are progressing towards digital product development (Best in Class) are realizing significant business benefits. The necessary technologies exist today and there are even standards that have been defined such as ASME Y14.41 to help companies make the move. If you are not already making the move to digital product development, it is likely that your competitors are well ahead of you.

Coexistence Strategy & Interoperability Best Practices for 3D CAD

2008-09-16T12:23:00.000-06:00

Introduction:

In today’s product development environment, it is not uncommon to find multiple 3D CAD systems in place at the same company. This can be the result of acquisitions, process driven requirements or perhaps user preferences.
With this white paper we simply want to review some best practices for a coexistence strategy where two or more 3D CAD systems may exist in on environment or company.

Coexistence can mean different things to different people. It is very dependent on your process. In some cases coexistence can simply mean that data from different sources are being managed in the same database. While in other cases it may refer to data level interoperability between multiple systems. This paper is focused on the later.

Important Facts:

“History trees” or “feature trees” cannot be translated to other CAD systems. A feature tree contains things like 2d sketches, parameters on the sketches, parameters defining a 3D operation and the parent/child relationship of the operations or “features”. There is no industry standard for the translation of this type of data. Very specialized feature tree translators are available, but are very costly and marginally successful.
Today geometry is the only common data between 3D CAD systems. Translating geometry is common and possible through standards like IGES, STEP and a few others. Custom, or specialized geometry translators are also available that can improve the success rate of a translation.
To translate a 3D solid model, all edges must connect to form a “water-tight” solid model. Connectivity is critical. Without connectivity, a solid model cannot be formed and what is left is a set of unconnected surfaces and/or edges.
All edges have a start point and an end point. The start point of one edge must match the end point of another in order for it to be “connected”. The “accuracy level” of a 3D modeling system determines how close 2 points need to be before they can be considered one point, or “connected”.

Most CAD systems run at different accuracy settings. This fact greatly complicates the successful transfer of geometry. Some may run at 1e-06mm while others may run at 1e-04inch.

Best Practices and Suggestions:

Set a company standard for geometry accuracy. This is not a trivial task, but will be the most important and effective step to take in developing a coexistence strategy. It may involve raising the accuracy of one CAD system, or perhaps lowering the accuracy of another. Understanding the impact of accuracy settings is complex. Consider the following:

CAD systems that allow for uniting, subtracting and intersecting 3D parts with other 3D parts will require that all parts involved in the operation have the same accuracy setting. Many 3D modeling systems don’t allow this type of operation and as such utilizing geometry of a different accuracy level may not be an issue.
Consider downstream operations that leverage the 3D models. Such as tooling. What accuracy level is required to effectively communicate geometry to the CAM system.
Consider other outside suppliers and partners. Is there a common level accuracy that can be agreed to?
Increasing the accuracy with some CAD systems will greatly impact the robustness of the system. Many CAD systems run at a lower accuracy setting to increase the ability to perform complex geometry operations. A blend, or round, will work at the default lower accuracy setting, but the same blend may fail at a higher accuracy setting. Push your CAD vendor to make high accuracy modeling more robust. If a failure like this occurs, it is a defect.

Choose a standard format for geometry translation. The common choices are IGES, STEP. The ACIS SAT and Parasolid transmit file formats are also good. Also consider that for both IGES and STEP, there are many different configurations available. Each CAD system may better support a particular configuration over another.

IGES is the most simplistic geometry exchange standard. Because of the many different configurations possible in IGES, successful “connected” translations may be very challenging, especially if there are significant differences in geometry settings between the sending and receiving systems. It is very important to know what configurations the two systems are expecting.
STEP is by far more successful than IGES at capturing the connectivity of a solid model. There are different configurations such as AP203 and AP214, but it is much more rigid than IGES. STEP is also capable of exchanging much non-geometrical data such as assembly structures, part colors and other attributes, 3D dimensions, notes and parameters.
Custom translators will of course provide the highest rate of success in exchanging 3D connected geometry. They are still susceptible to variations in geometry accuracy but can be much more “forgiving” of inaccuracies in the geometry, and are tailored to the exchange of geometry between two specific CAD systems.

Most all CAD systems also provide the ability to “heal” geometry inaccuracies on import. Check with your CAD supplier and understand what the capabilities are and how they work.

Many CAD systems also allow direct user interaction with unconnected geometry in such a way that the user can effectively close gaps that cannot be automatically closed or “healed” during import. Be sure to understand what capabilities are provided by your CAD vender for doing this type of work.

With a common geometry accuracy level and a determined best exchange format, geometry exchange can be very robust. You can now consider automating the translation of part data based on process requirements.

Consider using PDM related automation technology to perform translations based on check-in, state-change, or some other manual or automatic trigger, regardless of which CAD system it comes from.
Notifications can be setup if required to keep the project team synchronized.
Use a PDM system to help keep all data organized properly.
It is best to use PDM capabilities that will allow for multiple documents (models, neutral files, …) to be related to a single part. This will allow you to associate multiple CAD native formats and the related neutral formats to a single part object within the PDM system.
The neutral files (IGES, STEP, x_t) can be linked to the part within the PDM system and accessed from any CAD system.

Other Challenges:

Geometry translations should be done at a part level, not an assembly level. Translation at an assembly level results in a single file that contains all parts that make up the assembly. As a result, coexistence at an assembly level, especially with formal data management, can be very challenging. It depends on your requirements for coexistence. Requirements for access control and revisioning/versioning will be critical to understand before defining an assembly level strategy. If it is desired to translate all parts within an assembly, it may be best to consider a batch translation of each individual part. If it is required to translate the assembly “structure”, you will need to define acceptable practices for the management of the results.

Most typical “history-based” modeling systems have very little ability to manipulate translated geometry as there will be no history, or feature tree. The translated geometry will come in as one feature with no parameters, rendering the model non-editable.

Summary:

Keep in mind that a successful translation does not mean that the receiving system is superior to the sending system. It simply means that either the sending system is sending higher level accuracy data, or the receiving system is effectively healing the geometry. However, if the results on the receiving system are a collection of unconnected faces and edges, it is very likely that the sending system is sending geometry at such a drastically lower accuracy level than what the receiving system is expecting that the receiving system cannot heal the gaps without making unrealistic assumptions. All CAD systems have reasonably good geometry healing capabilities, but that can only go so far. Pay close attention to geometry accuracy.

Coexistence of different 3D CAD systems can be challenging, but it is possible with some careful planning in context with your product development process and requirements. Some trial-and-error will be required to best determine a suitable and acceptable accuracy level. The same is true when determining the translation format that produces the highest level of success.

For more information about CAD interoperability check out my article in Machine Design: http://machinedesign.com/ContentItem/72275/AnINTEROPERABILITYUpdate.aspx

Paul