I'm getting an error while trying to apply shell operation on tapered extrusion, which has 2 collinear edges with the base box. After removing taper or making a tiny extrusion on the top of the box, error disappears. But those are just weird ways to avoid the problem which shouldn't appear on such a simple part.
I took a look at this model. The problem should be related to the 2 collinear edges with the base box. If I offset the whole body(exclude the red face) with 2mm and then shell the part with 2mm via Inside option, the original collinear edge will be separately. Refer to the attached model and picture. Is this your expected result?
https://www.autodesk.com/campaigns/fusion-360/insider-program
This is supposed to be a part of air cooling system for 3D printer, so this result may count as valid. But I still don't like this unwanted corner that sticks out:
Then I realized that I can't get what I want geometrically with the initial part. So I tried to extrude into the base box from the front by 2mm before shelling:
But after shelling I got this tiny gap between round face and base box:
I think this tiny distance depends on taper angle and thickness of shell. I reduced that 2mm extrude by this 0.175mm gap and finally got the part I was expecting. Even shell thickness everywhere and no unwanted corners.
Thank you for help! I'll take note of your solution too, it may be useful in some cases.
