Hi Linker, thanks for reporting this.

It seems to be related to a really tiny micro-fold in one area of the upper lip:







You can see there that 2 of the surface's control points are kind of crossed in position with one another. That creates a really tiny folded area of the surface right there which really tends to cause problems in shelling or offset operations.

Was that made with a sweep? If you still have the original curves could you please post them? If that little jog back was not in your original curves it may be something that needs tuning up in sweep.


It kind of looks like that general area around the micro-fold is kind of a little bit more lumpy and bumpy than it looks at first glance. Shelling in particular is pretty sensitive to that type of stuff because the ripples get magnified after offsetting, and then shell tries to take that offset result and intersect it with neighboring offsets.

That kind of intersection where things are kind of wavy and barely grazing through each other is difficult to calculate.

- Michael