dkightley wrote: ↑Tue Nov 06, 2018 6:12 pm
3Try replacing your shape file with the attached file....and see if it slices correctly.
It does. I gather you've remeshed it in some other application (3D Builder?), which obviously recreates the geometry by redrawing the triangles and also changing the amount of triangles in the mesh.
So getting around the issue is possible, but that doesn't mean it's not a bug. Granted, it's a freak accident of a bug, as I've played around with the CAD model to see what affects it. Removing all of the inner structures and leaving just the frame still causes the additional wall to be made. The wall thickness of the frame is exactly 1.6 mm, which is exactly 4 perimeters. However, if you look closely at the file provided, you will see that at one of the short ends of the frame S3D feels the need to squeeze a thin wall perimeter in the middle of the 4 perimeters, so it creates 5 perimeters instead. And then this extraneous wall going inside the frame.
So again, it is most likely a small rounding error or something within S3D that causes this (and remember, it works flawlessly in 4.0.1), so even if it might not happen often, it should still be looked at by S3D to determine the root cause. The geometry itself has no errors (S3D also reports no errors), so it should not have caused this slicing issue.