FilletEdge Oddity

I’ve been creating an odd shape during which I encountered a number of Rhino behaviors that I found odd. Here is one involving FilletEdge.

  • At the far left I have the starting point.
  • Next I do a fillet edge, rolling ball 3.55" which does not work. I cold get one of the other two fillets to work but I needed the 3.55" radius for other things to work.
  • Joined the resulting surfaces together.
  • Finally I did booleansplit and I get the desired result.

It seemed to me that the FilletEdge command should have been able to handle this fillet considering how straightforward the workaround is.

Problem Fillet.3dm (522.1 KB)

Hello - FilletEdge fails to trim here because the radius is larger than the surfaces can accomodate -


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What it appears you are saying is FilletEdge cannot take into account adjoining surfaces.

In this particular case, extending the fillet into the adjoining surface produces the desired result.

Right- FilletEdge does not know about faces that are not attached to the edges being filleted - probably its prmary weakness…


Sounds like a wishlist item.

Oh yes…


The two failings Rhino has vis-a-vis my former ACIS modeler are fillets and shelling (fortunately, that is the full extent of my list).

I find that in order to shell I frequently need to:

  1. Remove the desired face (ExtractSRF)
  2. OffsetSrf the shell amount.
  3. Extend the edges beyond the opening.
  4. Trim to make the opening planar.
  5. Cap to create a SOLID
  6. Subtract this from the original to shell.