BUG: Rhino 7 is unable to untrim this surface

I used ! _BooleanDifference to create the bottom opening on this model, however, the inner revolved surface received a split line that can’t be untrimmed with the ! _Untrim command. I experienced that multiple times during the years with any kind of surface (not just revolved ones). Any suggestions how to overcome that bug in the future?

This Rhino scene consists the original objects before the Boolean operation. They are hidden.
Капачка за джанта.3dm (464.9 KB)

I see that V7 makes a mess - V8 seems to handle the coincident faces cleanly. The intersection is like so:


Yeah, I already fixed that by manual splitting of some individual surfaces that I separated prior that operation. :slight_smile:

Yep, it’s an invalid surface…

Funny fix - use ReplaceEdge and click the slit edge and Enter. Removes the edge and makes it valid.

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Seems like this solution must be displayed by default in the Command line any time a similar bug occurs. :slight_smile: