Failed BooleanDifference

Hello, I’m trying to engrave a pattern into a ring, and all but ONE of the polysurfaces subtracted properly from the ring’s surface. Any ideas on what’s happening here?

As you can see in the screenshots below there is a mysterious hole in the solid ring’s surface that doesn’t appear when looking at the inside surface of the ring.

Thanks in advance for your help!


Hello - this is a problem, occasionally, with Flow/FlowAlongSrf that I’ve encountered a bit more than I like lately - the flowed surfaces are refit to a fairly dense structure and the control points tend to get jumbled - the surfaces that start off vertical end up folding on themselves at a microscopic level.

Here, I moved one point slightly out of line so you can see the fold/overlap at the surface edge (arrow)

On this object, to get your work done, you can do the following and it should work:

  1. Explode the flowed part.
  2. Select all the side, or vertical surfaces
  3. FitSrf to .001, DeleteInput=Yes. This will remove a lot of control points and return a thing that is, hopefully, slightly simpler and not folded.
  4. Join and Join to the top and bottom surface.
  5. Boolean operation.

I don’t know if there is anything we can do to make this more reliable for small objects like this but I’ll try to corner a developer and see what he thinks.


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Thanks Pascal! I simplified the vector in AI, and then imported it again. It worked!