Shelling: Shell Result is not a solid

More often than not, when I shell something, I get the warning “Shell Result is not a solid” and a polysurface with naked edges that I have to manually repair.

For example, here, I have a solid that is not that complicated. If I try to shell to 0.03, removing the large, nearly circular face, I get the same error.

Problem17.3dm (162.1 KB)

I can manually go back and fix up the edges.

Is there some simple way to avoid this error and having to manually repair shells?

There are several ways to get a good result (all without the command Shell). The method we use most is to find the center of the object with the command centroid of area or volume. Then I make a copy using the gumball and pressing ⇧ + ⌥. Alternatively you can use the command-scale 3d always using the area centroid point of reference.
Finally, I create a small curve to the main subject with the thickness measurement and do match the object created with the gumball. To create an object will need to create a solid surface closing. In this case I used the command sweep with 2 “concatenate edges” active.
Problem17 offset gumball.3dm (319.8 KB)


Yeah, that one looks like it ought to work - thanks for sending that in.


Here’s another one that will not shell even though it looks simple.

I am trying to shell to 0.03" (Tried 0.01-0.04" as well) removing the smaller of the planar surfaces with a curved edge. However, I get the same problem no matter what surface I try to remove.

Problem76.3dm (212.1 KB)

Hi Jim - this works OK if the sides and the ‘vault’ are tangent all along the edges where they meet. My guess is that is the intent anyway…