I had a problem trimming a surface, and when I isolated the problem, it is surprisingly basic (see attached file) – I have a simple revolved surface, and when I try to trim it with a plane, it fails in both Rhino 5 (Windows and Mac) and Rhino 6 (Mac).
Trim_Problem.3dm (3.0 MB) (Rhino 6 version)
Changing the tolerance, even to extreme values, doesn’t help.
Intersect makes the problem a bit clearer:
– Rhino is getting the intersection between these surfaces very wrong for some reason.
In this particular case I will probably just find a workaround, but it seems surprising that this would happen in such a simple situation. It would be good to understand exactly what is giving Rhino difficulties here, as it might help to understand more complicated trim / intersection problems in the future!