Every so often I get asked to help one of our customers to work on a bad behaving mess of a model.  I jumped at the chance to do real design work and collaborate with customer on a project… and doing a little surgery on a Frankenstein monster model is a fun challenge.

About two weeks ago I was asked a few questions about an imported model that was giving the team some problems.  I offered to help.

The model was imported from Pro/E and probably spent some time in Inventor too.  The overall design was changing radical from a machine aluminum assembly to a composite design.  During that redesign, different designers made changes with different approaches and eventually the model just got into a bad state.

One of the advantages of having a direct and timeline-based design tool like Fusion 360 is that the direct editing tools are stellar at repairing model geometry.  I put together a three part video that walk through the steps and techniques I used to clean up the design.

This first session is just to get to understand all the ways things have gone wrong.

To summarize, we have several problems:

• Sliver faces from an extrude that did not match up to original shape
• Edits to a face that has caused it to introduce some loose tolerances along edges.  These tolerant edges can happen in some solid modeling kernels or thru some file formats used in data exchange. These can be a real bear to fix.

Let’s start cleaning up the model by getting rid of the unneeded faces.

Some key things to note:

• Learing to use the flexibility to capture edits in the timeline or directly edit the base feature is a powerfull option.
• To use select-other, hold the left mouse button over geometry then select from the list the entity you need. Use shift to add to a selection.
• Window select is a fast way to grab a bunch of faces.

Finally, we need to rebuild the bad edges and put the fillets we removed back.

A really good trick is to add geometry to consume bad faces or edges, or to cut these faces or edges away.  Here you can see how the rectangle cut quickly took an ugly set of edges and removed them.  From then on it was easy to finish the cleanup.  This projected ended hapily with the final design out for fabrication a few days after we started colaborating.  Capturing the versions and being able to mcomment back and forth really helped me get the information needed to make the repairs quickly.  Fusion 360 has translators for most common CAD formats. You are bound to get a bad IGES file or two.  Having the direct modeling tools and some simple techniques can make short work of any cleanup and repair you might need.