Shell failed :-(

The shelling (0.8) of the upper face is not working. Check please.
shell failed x.3dm(326.0 KB)

You have two tangent cylinders that cannot be extended, you have to add either two planar surfaces or a tangent surface between the two cylinders.
I made an example with a tangent blend.
Rhino would need to have a lot of added intelligence added to this command to ask for your preference in such cases.shelled x.3dm(233.9 KB)

Interesting Marc. I’ve looked at both files. Not sure I understand what you did and what you mean by “have to add either two planar surfaces or a tangent surface between the two cylinders”.

Would love a series of the steps in the layers or a video example. I know that’s a lot to ask, but would be sooo helpful!! Shells have been a problem for me as well. Would love to learn how to fix these situations.

This does seem to be something of a special case. I see that SolidWorks fails at the same location- the difference being that Rhino does give you a result you can work with to get the final result =)

-Pascal

The problem is because shell does not have the option corner=round.
Ciao Vittorio