Problem shelling a split chamfered box

alex_franke

Hi there. I'm new on onshape and I'm stuck with an unexpected behavior that I hope I can get some advice on. I'm just a hobbyist, so please go easy on me! 

Basically, I chamfer three edges of the top of a box, and fillet the other edge to make a box and a lid. I build a cutting surface using a line from the chamfer and a point from the fillet, and then split the solid into a box and a lid. Each part of the split looks exactly like I'd expect at this point, with almost all of the chamfer "cut off" to make the lid. When I shell the box, though, I get an internal chamfer where I expect to see just a straight wall. 

 

It's as if using a point from the fillet for the split changes how the shell operates. Any hints on what I might be missing here? 

I tried to distill it down to a simple example in this document, which should be publicly accessible:  https://cad.onshape.com/documents/62ed735cb4d9046e79d04259/w/663f09afcd3ea47775d845fe/e/1e152b0feee70a7ccdc76e27 

Thanks so much!

john_mcclary

Yea, that is weird. I'd contact support with that one.

It appears to be trying to match the chamfer because it shares a common edge (shown below)


as soon as you offset that common edge, even by .001mm the problem goes away.


but you could also use delete face and trim those chamfered faces away too

john_mcclary

Yea, that is weird. I'd contact support with that one.

It appears to be trying to match the chamfer because it shares a common edge (shown below)


as soon as you offset that common edge, even by .001mm the problem goes away.


but you could also use delete face and trim those chamfered faces away too

alex_franke

Thanks for the great tips, John -- I hadn't even explored Delete Faces yet. I'll leave a note for support so they can add it to their list.