Designing parts in a top-down manner in old CAD systems has always been a struggle. You can design in the context of the assembly, but that process has always been fragile, with the model often updating in unpredictable ways. The other option for top-down design that you have with an old CAD system is called “multibody” design, but this technique comes with its own unique set of problems. Let’s take a look.

Wistia video thumbnail - Parametric Modeling 2.0: Multi-Part Design

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“Multibody” design essentially means you can design multiple “bodies” within the same part file. Below is an example of a concrete bucket designed with a “multibody” technique. Notice the 41 solid bodies.


The problem with designing this way comes when you try to insert these bodies into the assembly.

It doesn’t work.

In old CAD systems, bodies must be exported as individual files before they can be inserted into the assembly. So for our example, I must export all 41 bodies as individual part files. And only after that, can I insert those files into the assembly.

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Aside from being tedious and confusing, this workflow also has a lot of potential for error. For example, say that I wanted to change the concrete bucket. Do I change the original multibody part file and export everything all over again? Or do I open all the intermediate files that were generated in order for me to create an assembly?

With all of these headaches, we saw a huge opportunity to improve upon a core CAD feature that engineers use everyday.

So how does Onshape solve this problem?

The answer is the Multi-Part Part Studio.


In Onshape, you can design multiple parts in a single Part Studio. These are real parts (not bodies) that are treated no differently than any other parts. They can be inserted directly into the assembly, or into the drawing without any special steps. And they can have metadata like Part Number, Revision, and Description applied just as easily. Most importantly, a design change in the Part Studio is immediately reflected in the assembly, so no need for additional steps.

Interested in learning more about the advantages of Onshape’s Multi-Part Part Studios? Join me at our free webinar this Thursday.

Join Onshape’s Cody Armstrong as he demonstrates how modern CAD has made multi-part design easier and more productive.
When: January 25th at 1PM EST