Offset surface

I have made a mold to make a vacuformed thermoplastic clamshell box liner. The mold is a closed polysurface. The surface I pulled off of the mold does not have any naked edges except around the outside. But when I do an offsetsrf of .75mm in the -Z direction I get naked edges on the fillets at each end. Is there a way to get this surface without manually rebuilding each naked edge?

I do not need to have a closed polysurface to make the mold, but to learn what I need to do in case the next time I do need that part to be a closed polysurface.slide holder clam box mold 001.3dm (9.4 MB)
Thank you

Hi Kevin - the problem, I would say, is in the .027 filets along the bottom of the ribs:


Those are consumed in the offset and the ends are messy.


Can anything be done other than remake mold with larger fillets?

I’d say the easiest would probably be to fix it surgically… it’s going to be a bit of a pain - hold on a bit, I’ll see if I can give you better advice…
OK - some are easy: ExtractSrf, delete and replace with a Sweep1 - I’ll make some pictures, hold on.

ExtractSrf & delete these:

Looks like that will work on all of them.

Replace with Sweep1:


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Pascal, Thank you for the solution. one question, how do you know how many control points to rebuild it with? I tried 3 through 8 and only the 5 seemed to consistently work. Thanks again

Hi Kevin - it looked about right and I tried it and Join worked… as sophisticated as that…