When I got to this one feature and detailed it , I quickly saw that this was not done with a sketch and revolve. I scratched my head and looked at the ZW3D model. I realized he create this shape with an arbitrary dome. Now, he was just having fun and this was not a production part, it was just an exercise in 3D modeling.

Why would you want to detail the part?

What if you wanted to modify the non-native model and it was corrupt or you could not directly edit it and you had to recreate it.

An example of this situation would be with Boeing having 2 completely incompatible 3D CAD packages, Catia 4 and Catia 5. I am sure many of the Catia 4 parts would have to be modified since all the airplane models were created in it until the 787. All CAD was done in Catia 4 until the release of Catia 5 in 1998 and continued for many years. Sadly, the transition to Catia 5 was fraught with problems. Catia 5 could not modify Catia 4 parts directly. I am not sure how Catia 5 read Catia 4 parts, today, the last time I was involved it was with STEP files. So, they would have to detail the Catia 4 models and recreate them... maybe?

Could have I put the similar dome in IronCAD? Probably, but that was not my concern at this time. I had ZW3D and the model available to scrutinize. But what if I didn't?

I realized something about the direction of 3D modeling.

If I did this part, it would be with mechanically defined features, playing or not, with a precise sketch and revolve. It is just the way I design.

Constrained Sketching and Streamlined Sketching

In the beginning 3D CAD, including Pro/e (Creo), was promoted as a way to create faster drawings. We would create the 3D model and detail instances of the part in different views in the drawing module. We could add annotation and the drawings were done to the existing drawing standards. The programs were focused on standard design. Remember only draftsman used CAD in the beginning. Engineers didn't widely transition to 3D CAD until it moved to the PC at the turn of the century.

The 1980's - 3D CAD - The Beginning

I complain about those that only do constrained sketching, but with his concept you are forced to do true mechanical design. Yes, i know you can screw up a model with sketches but mostly things are done correctly.

But, it mostly demands that you do mechanical design that can be easily detailed.

I push Streamlined Sketching that uses horizontal, vertical and angled lines and use offsetting and trimming to create my sketches. No constraints. But still mechanical design.

Good sketching mostly leads to good duplicable mechanical design.

Enter Direct Editing

I used 2D/3D wireframe, surfacing and Boolean solid modeling in the beginning. It formed my modeling techniques, the reason for Streamlined Sketching.

Feature based direct editing showed up with IronCAD in 1998 and soon CADKEY also had implemented it. In the beginning Boolean modeling was very primitive. You would split a model and many times you could not join it back together. But the ACIS and Parasolid modeling kernels were constantly improving.

With the introduction of SpaceClaim and Siemens Synchronous Technology direct edit finally matured to an acceptable viable modeling process. CADKEY and IronCAD already had it so I was a bit ahead of the game. CADKEY was a direct edit only package and I feel without history you only have half of the 3D design functionality. IronCAD is the only truly integrated history based/direct edit 3D modeler. You use both modeling techniques in your design process.

Detailing: Completely defining the shape of the part by adding dimensions, in a way that defines the relationship with the mating parts.

Now I am a mechanical design draftsman that believes in completely detailing my parts and delivering an AID (Associated Information Document (drawing)) along with the 3D model as a reference document. I do this to check for errors or many times a better design. I find this step invaluable to eliminate problems later.

A Short Primer and History of Dimensioning

The Death of the Drawing

So, my direct editing is always focused on keeping the part something that can be easily detailed. Just the nature of a manual based design draftsman. Now, direct editing can modify a part beyond the level of detailing with rotated faces and other obscure face moves.

Now, I have referenced textures and text graphics per the model.

Direct editing has not been widely adopted due to the poor implementation in the Pro/e (Creo) clones that have not made it effectively available in the design process.

But soon the 3D modeling paradigm will change and direct edit will be a viable function use along with history based design in the design process. This will open the door to incredibly flexible modeling especially when modifying the 3D model increasing productivity 5 to 10X.

Is 3D CAD Productivity an Oxymoron?

Will the concept of mechanical design in the sense of precisely defined documentation be used?

Now, you can also add the introduction of surfacing in your design process. While you can reference the process, you cannot precisely document it. When you think of advanced surfacing you think of an auto body. It really is not much different. Since the shape was not based on drawings but a clay model.

Here is a reverse engineering job on a 1959 Corvette bumper. I had some problems, imagine what the pattern maker went through? Was this part detailed? I have my doubts, it was probably developed from an actual model.

Reverse Engineering Success! 1959 Corvette Bumper

MBE (Model Based Enterprise)

Are we going to the level where the model cannot be defined by dimensions and the 3D model is the only document?

Personally, it reminds me of a time I was under contract at Williams International.

The chief draftsman (a field promotion) demanded we use limited tolerances for all dimensions. He said we will not have any non-thinking tolerances.

I was a young draftsman and I told him if we did that all dimensions become important.

Why?

In those days we had UOS (Unless Otherwise Specified), we would use decimal places to show the importance of the dimension. X.XX = +/- .03 X.XXX = +/- .010. Now that was at Boeing and it may be different for different industries. That was when they turned knobs to machine. Today, any machining can hit .005 in CNC so I suppose it would change the priorities in design and tolerancing.

The machinist could instantly see what was important and what wasn't.

This added a new level of complication to the process. The cost of the parts would soar. Imagine each dimension would have to be calculated to find the basic dim? Very short sighted, that Chief Draftsman.

Now, we move to freeform 3D modeling and this concept is reversed. Virtually no way to effectively review the part. Just directly model the part with no restraints? Are approved form, fit and function design standards to be used?

With manual drafting all of our circle templates and scales were were in eighths and tenths. Manufacturing worked on the same basis. We designed to standards.

My point being are we going to the other extreme? Minimized dimensioning, maybe only controlled by minimized GD&T, covered by obscure profile feature control frames?

Here is an example of minimize GD&T in the PMI format. Now, I actually detailed this part as you can see in the article below. But is this the beginning of undefinable parts?

PMI vs AID

I am sure you could throw any part into the AID (drawing) module and scrutinize it somewhat. But it could become a free for all.

No detailing Required?

Now, this is a question we must ask.

Are we moving toward non-thinking design?

Enter Generative Design

I am not going to do a definition, they seem to be a bit proprietary, you can google it for yourselves. Autodesk seems to be deep into this technology. I will just show this image.

One of the problems I instantly saw was documentation. I suppose besides the final model you would have to also include the original model with an AID that would define the software and the necessary steps to create the final model plus material, manufacturing process, finish, etc.

This actually looks like a legal nightmare.

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If you would like more information or to download ZW3D or IronCAD

With 53 years of experience in engineering, 17 years in manual board design as a contract engineer, 35 years in 3D CAD sales, support, training and providing engineering services, I have a high level of understanding of today's 3D CAD engineering world. For many it is in chaos. If you are having problems or just interested in this subject please feel free to call and we can discuss them. There are so many simpler solutions available that will save you time and money.
   
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Joe Brouwer
206-842-0360