Tips for Converting CAD Data

If you participate in a “digital” design and manufacturing process you are probably sharing or receiving product data in digital form - usually a CAD file. Physical products seldom consist of a single part and are rarely designed and made by a single individual. Engineering is a team sport.

Digital design and manufacturing on GrabCAD Workbench

However, sharing CAD files often means translating the file or converting CAD and its contents from one format to another. Why?

  • People sharing CAD files are using two different CAD systems.
  • They’re using two different versions of the same CAD system. Our Community members frequently face this problem!
  • Collaborators might not be using a CAD system at all, maybe they're using a manufacturing or engineering analysis application that works with 3D geometry.

Lost in translation

Often, the best way to exchange CAD data is through a neutral format, like STEP. All major mechanical CAD vendors are committed to making exchange of data through the STEP format as complete and accurate as possible. However, we learned in a previous blog post (GrabCAD Tips: The Kernel, Why CAD Systems Don’t Play Well With Others) that data translation often means lost and inaccurate data.

Lost data in translation

So, what other techniques has GrabCAD seen engineers use to minimize data loss when exchanging product information?

If you have to send a file...

Remodel parts from scratch

Sometimes rather than attempt to translate a file from one format to another, an engineer will simply “rebuild” a part from scratch in their system of choice. Although this can be very time consuming this happens more frequently than you’d expect. We’ve heard from some community members that parts a remodelled multiple times before they are manufactured. This seems like a tremendous effort simply to work around different CAD systems having different math representations for geometry.

Use direct translators

Some CAD systems have “direct” translators from their internal format to the format of other CAD systems. Sometimes these translators generate native CAD files. Sometimes they generate “kernel” transmission files that can then be imported into other CAD files. These translators MAY produce better results than going through a neutral format since geometry is translated once, not twice. But if neutral format translation is not acceptable it is likely that direct translation will also be unacceptable.

Exchange exported kernel files

If two CAD systems use the same geometry kernel, then it is possible to export the kernel geometry from one system and import it directly into the second system without translation. This is the best way to exchange geometry between two different CAD systems. In some instances kernel formats are even backwards compatible. However, kernel formats lack non-geometric information like assembly structure.

Better yet: don’t translate - collaborate

Often the goal of sending a file is simply to let another party view and comment on or markup your model, not to let them modify the design. If that’s the case, then take a step away from the kernel discussion and think collaboration tools, not CAD authoring tools. This is why we built GrabCAD Workbench, which allows you to share a 3D model with anyone, regardless of whether they use CAD. Your partners can view any CAD model in their web browser or on their mobile device, make comments, measure and sketch on the model and keep everyone up to date.


So next time you need to share a CAD file, first ask, “What is my goal?”. If you need your partner to modify the design, think through the tradeoffs of STEP vs other file transfer methods. If your goal is simply to communicate, try GrabCAD Workbench and stop worrying about kernels!