BooleanDifference creates a bad mesh

Hello! When I run a BooleanDifference command on the inner arrows that cut through the whole layer of the ring, creating a mesh from NURBS and running a check on it shows that it is a bad mesh, for a variety of reasons every time.

However, there doesn’t seem to be a problem with the solid that is cutting into the ring - I’ve tried making a mesh out of that and checking it for issues, but there are none. They only appear after using the BooleanDifference command. The outer outline on the arrows that are engraved doesn’t create a bad mesh - only the inner arrow that cuts all the way through. What can I do to solve this? (new to Rhino)

I plan on 3D printing this ring, and thus need a watertight mesh. Thank you in advance for any help!

DDR Ring.3dm (12.8 MB)


The issue was with lots of closely spaced control points, possibly overlapping some. It’s an easy fix… see the video below.