Degenerate surface curves on trimmed surfaces (surface curve intersects with itself)

This problem is usually encountered with badly defined trimmed surfaces imported through IGES, SAT etc. where the tolerance of the curve was not accurate enough in the original file. To confirm that this is the problem, explode the trimmed surface and immediately re-trim it again. The error “Surface curve intersects with itself” occurs if the curve is degenerate.

Solution: Explode the surface and edit the surface curve.