Hi Leonard, also I've been examining the chamfer problem some more - it seems to be a general bug in how chamfer handles the "corner patching" pieces when 2 edges meet each other at an angle of less than 90 degrees like when you have a triangular shaped hole.

I've been able to repeat the problem when making a simple triangular hole in other simple models separate from yours.

I may need to send it in to the people who make the geometry library that I use, but identifying a general pattern to the problem can help to isolate it down.

- Michael