Which CAD Paradigm is Best?

Solid Modeling is as close to creation as man has ever achieved. Today we can create anything we want, rotate it, view it, render it, animate it, etc. I will never forget the day when CADKEY (The first effective PC based 3D CAD system, now KeyCreator) released its first real time hidden line removal. No it was not in full solid color like we have today it was basically a wire frame on a black background. It was a miracle.


These are the paradigms presented in today's CAD world.

1. The Electronic Drafting Board

Notice I didn't say 2D. Unless you are creating flat patterns, you are usually using this to create drawings. Drawings are not 2D they are documentation describing real world parts, notice I didn't say 3D parts. Autocad was introduced in 1982 on a PC, providing the architectural world basic drafting. Many took this to the mechanical world. Luckily, my first CAD experience was detailing views generated from a 3D part. I did play with Autocad, it was an incredibly painful experience. It was truly not the tool for mechanical design.

My First 17 Years or "How did we do it without 3D CAD!"

The Death of the Drawing

The Death of the Draftsman or “Where has all the talent gone?” 

To Draw or Not to Draw

Redefining 2D/3D

2. 3D Wireframe

I was introduced to Computervision CADDS 4 in 1982. It was a 3D wireframe product running on a supplied computer running in a refrigerated room, $250,000 per station. This was the introduction of a new way to design. While on contract with Boeing in 1985, I found PC based 3D CADKEY on 2 Compaq computers . After two weeks of lunch hours, I convinced management that this was the tool we should use. We were using IGES to communicate with Catia, which was also 3D wireframe with some basic surfacing. Cadkey was the first big player in the PC based 3D CAD market.

1982 3D CAD! The Beginning 

3. Surface Modeling

This was introduced in the mid 1980's. It was a boon to the industry. You could create net surfaced parts that could be used for 3 axis CNC and stereolithography (3D printing). A company asked me to add draft to a plastic part and add surfaces for 3D printing. Using Fastsurf, I quoted 55 hours, they were shocked "it didn't take us that long to design". I just said "Well, you should have designed it with draft." Later I did a similar job in solids and it took me 15 hours. Robert White created Fastsurf as add on product for Cadkey. 

Today, about 10% of us use surfacing. Solid modeling can not get down to some of the more swoopy designs or transitions. Surfacing is not a good paradigm for mechanical design because of it lack of associatively and ease of editing. Most of the popular packages provide intermediate surfacing capabilities, that usually get us to about 95%. But there are advanced surfacing products like Alias and some surfacing provided by the high end packages to fill that last 5%. Here is an article where we had to have help to finish a project.

The image on the right is a Surface thickened into a Solid Model.  

Reverse Engineering Success! 1959 Corvette Bumper

AK-47 Project - Reverse Engineering 2015

4. Solid Modeling

This is the world where most of us live.

 The Worst to Best CAD System and Why!

The 1990's - 3D CAD/CAM Moves to the PC!!

Parametric History/Feature Based Solid Modeling Paradigm

This format was introduced with Pro/Engineer in 1987. It is a somewhat complicated design system. It has a very precise history base parent/child feature construction system. The parts have to be created in a certain way. Enter “Design Intent”. You have to really understand your design before you start creating the part. You have to understand how it is to be made and dimensioned. It should have really been called Pro/Designer. If the part is designed correctly you can have an automatic drawing. This is probably where the focus on the engineer being a CAD designer started. Now don’t get me wrong Pro/E is a very good program with many add on analysis functions, which does make it a good tool for engineers.

This system is very complex and hard to learn, causing the user to have to be a regular user. When you design a part the features are based on the earlier features. The skill and expertise of the user is paramount when using this system. When designing a part an experienced users has few problems. The problems show up when you have to change the part. The original designer even has problems with his own design if he is away from it for as little as a month. But the designer that has to take over the job may not be able to make the changes and may have to recreate the part. If this is a released part this can be very dangerous.

The Pro/e paradigm became the de facto standard. Soon Solidworks showed up, started with the help of some ex-PTC developers. It was soon purchased by Dassault Systemes which soon implemented this paradigm in its Catia 5. UG was releasing Solid Edge in 1996. Autodesk Inventor soon followed in 1998.

All of the above product use the Pro/E paradigm and all have the same problems. A very structured design process. It was soon found that this paradigm was very limited in interoperability. They could not use any of the others systems data. With Solidworks there were attempts to automatically create the history from non-native files but it was marginally successful. Even now you can recognize features but it leaves a lot to be desired.

5. Explicit or Direct Edit Solid Modeling Paradigm

Smart Parts - Dumb System
Dumb Parts - Smart System

"There are basically no complex parts with direct edit!!"

Next Generation CAD Technology Applied!

Next Generation 3D CAD!! The Win-Win Solution!

Standardization! The Future of 3D CAD!!

Reusing 3D CAD Models for a New Product

The 2000's - The Age of 3D CAD Un-Enlightenment!

I was selling CADKEY in 1986. CADKEY was a wireframe modeling package. There was a surfacing package called Fastsurf. Both programs offered a very good modeling package. Solid modeling was introduced in as FastSolids, this was a direct editing solid modeling system utilizing Boolean operations. I started my solid modeling at that time. The only other solid modeler at the time was Pro/E and it was my only competition. But it of course was in a different class offering much more engineering analysis.

CoCreate was also around at this time. It was a direct editing program. Now is being offered as a standalone product within PTC Creo. It can be worked with PTC Wildfire offering the advantage of direct editing. PTC knew that they need this functionality to be able to work with non-native parts from other products, such as Catia and Siemens NX.

What do the popular CAD packages say about Direct Editing on their websites to promote this concept.


  • Easy to Learn
  • Easy to repurpose design

  • Lightweight - Smaller file size

  • Flexible

  • Rapidly evolve and explore designs

  • Maintain flexible design teams

  • Work with multi-source CAD data

  • Rapidly iterate designs

Siemens/NX/Solid Edge ST (Synchronous Technology)

  • Design experience 100X faster than closest two competing CAD systems

  • ECOs in seconds vs. hours

  • Biggest CAD breakthrough ever

  • No remodeling -- Edit foreign CAD data faster than in native package

Autodesk Fusion

"3D Modeling for Rapid Design Changes"

"Autodesk Fusion is 3D modeling software that showcases intuitive direct manipulation capabilities for unrivaled ease of use. By uniting direct modeling and parametric workflows, Inventor Fusion offers the best of both worlds. Designers can freely explore complex shapes and forms while maintaining the underlying parametric history. Inventor Fusion makes it easy to open and edit 3D models from almost any source and incorporate them into your design, enabling rapid design changes without limitations."

SolidWorks Conceptual Design

"Make Conceptual Design Your Business Advantage"

"Innovate in an instinctive, powerful modeling environment that gives you the freedom to design the way you want."

"Innovative conceptual design is the core of any successful product. SolidWorks Mechanical Conceptual, powered by Dassault Systemes 3DEXPERIENCE Platform, gives you an instinctive, powerful modeling environment focused on the four key elements of conceptual design:

  • Conceptual

  • Instinctive

  • Social

  • Connected

Dassault bothers me a bit with the name of their new product. What were Solidworks users doing before this product? Non-Conceptual Design!! Solidworks has been here since 1995. I don't even think this package has detailing functionality. So you still have to keep your Solidworks. At $2988.00 subscription per year, there are many better solutions that offer more flexibility and equal productivity. Also it is written in a different modeling kernel, we know that Dassault wants to get away from paying Siemens a royalty.

Direct Edit as an Add-on?

So today PTC Creo (Pro/E with CoCreate), Siemens NX (Solid Edge) with ST (Synchronous Technology), Autodesk Inventor with Fusion and soon to be released Solidworks Mechanical conceptual now all offer Direct editing. They see the writing on the wall. Today we need both paradigms. This leaves Catia 5 the only package without direct edit capabilities. Catia 6 is supposed to have it also, but those large companies that use Catia, like Boeing are probably a bit gun shy to move from Catia 5 due to the fiasco of the last move from Catia 4 and the incompatibility with the two versions, which they are still suffering. I am sure Boeing would have not purchased Catia 5, but now are stuck with it.

Update: 6-21-2016

Sadly these Direct edit add-ons have not provided the necessary functionality to allow them to take advantage of this productive tool. I have come to the conclusion that the dated Pro/e paradigm cannot effectively integrate direct edit functionality to use in the design process.

Universal 3D CAD Compatibility is "Not Here"!!

Welcome aboard Solidworks Reecrite!

Solidworks Users are "NOT" Stupid?

Is 3D CAD Productivity an Oxymoron?

6. Innovative Part Design

Innovative Part Design allows users to build a non-restrictive history of features that make up the design aspects of the part. Although it has a history of features, the system allows the user the ability to dynamically change the history order without inverse effects of feature dependency rules and restrictions. SmartUpdate technology within Innovative Part Design aids the users by intelligently managing the feature history giving predictable results when changes are made by the user. Innovative Part Design also provides a level of flexibility by allowing the user to refer to geometry elements regardless of the history order in which the geometry appears. This flexibility allows the user to work as if they were working with a physical object in their hands eliminating rules implied by the system.

We are going to rotate the motor and revise the tube.

Here is an easy drawing of the change. No constraints, no modification of any released parts. The complete assembly in one file where all of the attendees can have and do a variety of concepts.

Since the Innovative Part Design supports features, users are able to add specific design rules to create parametric design intent. The advantage in this approach is to apply intent when needed allowing the user to place only the critical design intent during their design process without the need of system applied rules that may not apply to their design task. Below we put in the holes using the center of the corner radii. When we pull on the block the holes stay centered on the corner radii. Now of course we can constrain the holes if required.

Drag and Drop Design from Standard or Custom Catalogs

This is where you pull feature shape (positive and negative, custom shapes, parts and assemblies from a catalog to do your design.

Environmental Paradigms

The Pro/E paradigm

This paradigm has three separate modules. A part, assembly and a drawing. This means you have to start naming parts as you begin your design. All parts are external. You can design in the assembly mode which doesn’t seem to be a problem. But PDM becomes a problem even if you are working alone.

UDE (Unified Design Environment) or Single Model Environment

This paradigm allows multiple parts in one file or space. Instead of creating external parts, parts and assemblies can coexist. This much easier in conceptual design. All of the parts are available. They can be set up as external parts as the project demands. No PDM until the job is done.

Which is the Best for Conceptual Design?

Now that we have defined a few paradigms, which I am sure, many of you where not even aware existed.

Let's take a look at some examples:

History based

This is a picture I am sure is familiar to many of you.

This is a relatively simple part. Now, you are not the original designer and you have to make the changes as shown in the next example. What do you have to do? You have to study how the part was made. The original designer could easily make the changes, probably not as quick as the next example, but much faster than the new designer. But from my experience, the longer you are away from the part the more difficult it is to remember how the part was made.

IronCAD vs Solidworks and the Pro/e Paradigm

Direct Edit or Explicit Modeling

Remember - There are basically no complex parts with direct edit?

Now look at the above example. I have done some arbitrary changes to the part. Adding and modifying features. I could have easily eliminated some also. On the left is the feature tree, notice that the basic shape is one Brep. I have done many modifications that do not show up as features. This is the results of direct editing faces. Notice in the menu, on the upper right, you can see the Direct Edit functions that are available inside the program and are also available with the push of the right mouse button. Since IronCAD history is integrated, I have shown some features, like the linked holes and the chamfers. This all was done in about 5 minutes. How long would it take in SW?? Don't get me wrong, I am not one of those people that says any system is faster to design, since design is not a race. Design is a thoughtful procedure that is based on knowledge and experience. But I am showing you a more flexible design process of having both history and direct editing paradigms being directly accessible in one program. This is not having the best of both worlds, this is truly having a new world!!

Please notice that both of these parts coexist in one file. They is no separate part and assembly mode unless required by commonly used parts. This is called UDE (Unified Design Environment).

Design Intent

Design Intent is "absolutely" required with a Pro/E history only based system. You really have to plan your design before you start. In my view point this limits your freedom. This is a huge advantage of direct edit packages. I don't like to design in direct edit only package because I like the freedom of having my features easily available to me. I want to have the ability to design in history, but have the option to directly edit a face if required, instead of going back up the feature tree to a point where I can make the change without any repercussions.

This is an example of utilizing a direct face edit in the midst of the design process.

Here is a shelled shape. We select the face and with a right mouse click with select move. The Tri-ball comes up to manipulate the surface. We are going to rotate the selected face.




We rotated the Face 15 degrees.



We had a shell function in the history this shows that the shell did get upgraded.



Imagine working without worrying about the design intent. You have the freedom of incredible conceptual history design with the ability directly edit the part when the design requires it.

History or Direct Edit?  The winner: History

In my opinion, History is the best for conceptual design. No matter which history program you use, having access to the feature for change is by far the fastest and easiest way to go. You can get the job done with direct edit, but it just is not conducive the with new design.

But to change the design, history has some problems depending on the complexity of the part. Direct editing has some huge advantages. When you edit a part you don't have to worry how the part was made. If you watch a webinar of direct editing only packages they usually show how to edit parts, rarely on conceptual design.

But why settle for one paradigm when you can have both. IronCAD has both integrated into the system!

This is not having the best of both worlds, this is truly having a new world!!

The Design Environment! The winner: The Single Model Environment

Now lets take a look at the design environment. The separate part and assembly, which may be the answer in the 1980's, is a bit of a clunker today. You have to start naming parts and putting them in your assembly. Yes, I know you can design in context and create the external parts in the assembly.

But to design in a Single Model Environment allows much more productivity by putting the data management on end of the project instead of up front. Many times the parts are unique to that project and can be left in the assembly to be detailed from there if required. Some times the parts may not be used and you may still have them as useless parts. This is a much better environment for the individual designer and smaller projects. I believe this is the most important process to increase productive. Sad to say there is only one history base system that utilizes the UDE, which gives it a huge edge in productivity.

What's been left out?

Innovative Part Design and with Drag and Drop Functionality!

Why? Because they are only included in one package, IronCAD. Incredible freedom in design with Innovative Part design. It is the only package with standard catalogs or custom catalogs that can have common parts for different projects from which you can drag and drop

IronCAD is also the only package with both History and Direct editing integrate into one package. Why would you suffer with clunky external direct edit modules when you can have ability to direct edit with a push of the right mouse button. We know that most design does not require direct editing functionality, but would it be nice to have it part of your design capabilities.

IronCAD the only history base system that is UDE. Just start doing your design. All parts and assemblies are available to you. Create as many iterations of your design as you want without worrying about external parts. You can copy and paste parts and assemblies in the same file or a different file. Just imagine how easy that would be. You don't care where the part was made you just start working on the part. No need to access a separate module.

We are describing a high level of freedom and flexibility in your design. So it is not a paradigm which is best that is important, it is a program that offers all of the paradigms for conceptual design in one fun, yes fun, easy to use package.

Take a look at this article.

Five Functions that Increase CAD Productivity!!


Leverage Your Engineering Data Series.

Leverage Your Engineering Data throughout your Organization!

Sales, Publication and Marketing

Checking, Design Review, Manufacturing and Data Extraction

Simplifying Your Design Process

So take some time to look at IronCAD, you will not be disappointed.


Enter Hybrid Modeling - No Design Limitations

The Ultimate CAD System

Beyond Direct Edit: Surface and Hybrid Modeling


Hybrid modeling allows wireframe, surface and solids to coexist in one useable space. This is where the major CAD programs are heading. But with their structured design process they may not be able to integrate it into their existing products. Dassault may be the first to confront this inadequacy in SW with the introduction of Mechanical Conceptual. This looks like an attempt to incorporate robust direct edit functionality. But I am not sure who will use this package, both of my solutions easily outperform it and at an annual cost of $2988 it does not seem to be cost effective.



Even though ZW3D is much like SW (more like NX) in operation, it is much easier to use since it can easily do complete projects in one file. IronCAD/INOVATE offer a much easier paradigm for conceptual design, but when you have to step out of the solid modeling box ZW3D offers that extra flexibility. You truly want to end up with a solid model. Especially if you have to deliver a company for further development.  

The Incredible CAD Combo

Update 7-20-15

Reverse Engineering

ZW3D always had advanced capabilities handling "point cloud" data. Mostly in turning them into surfaces. It also could work with .stl files on a rudimentary level. But that all changed with version 2015. They added a robust menu of functions that can manipulate .stl files not matched by programs at 10x the price.

Take a look at the menu:

To do reverse engineering you need full hybrid modeling functionality. You need wireframe, advances surfacing and, of course, solid modeling. Take a look at the project below and the ease of converting "scanned" data in to manufacturable parts.

AK-47 Project - Reverse Engineering 2015

TECH-NET Engineering Services!

We sell and support IronCAD and ZW3D Products and
provide engineering services throughout the USA and Canada!

If you are interested in adding professional hybrid modeling capabilities or looking for a new solution to increase your productivity, take some time to download a fully functional 30 day evaluation and play with these packages. Feel free to give me a call if you have any questions or would like an on-line presentation.

WARNING: ZW3D is a professional 3D CAD engineering package and it is not recommended for those who are not engineering professionals or students with no prior 3D CAD experience. While we will help you get started we are not equipped at this price to teach you 3D CAD from scratch or engineering design. Don't let this low price fool you.

ZW3D now imports native Catia 5 files with PMI


Four Functions that Increase 3D CAD Productivity!!

Reusing 3D CAD Models for a New Product

IronCAD vs Solidworks and the Pro/e Paradigm

Joe Brouwer

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