Version 5 SR12 64-bit
Made a piece of U channel 101.0 x 50.5mm. Import curve from .ai file.
I have a surface that when extruded, some surfaces distort. (see attached 3dm)
I can fix it by deleting the 2 radius curves, _Arc , join, extrude …
Just not sure why the radius curve(s) in the surface caused the issue.
Extrude surface (Channel).3dm (76.9 KB)