Greetings -

Having trouble shelling a part.  This is an imported file that was provided to me as an IGES file, I think the original part was created in Pro-E.  Unfortuntaely the part is proprietary so I'm not allowed to share it publicly; the best I can do is describe the problem verbally.

The part is a domed pressure cover.  Imagine a hollow hemisphere with a bolt flange around its edge, and you've got the basic idea.  Except it's not exactly a hemisphere, it's a somewhat more complex shape made up of a bunch of curved surfaces, and there are a couple of auxiliary penetrations that are accompanied by smaller bolt flanges on the exterior of the "hemisphere."  The flange face is approximately 8" by 10".

In most places the thickness of the cover is 1/4-5/16".  We want to produce a plastic prototype part, and in order to cut cost, we need to reduce the thickness of the cover to about 1/16".   I am trying to "shell" it, but I keep getting errors, and I'm not sure how to fix them.

Once the IGES file is converted to Solidworks the only feature listed in the FeatureManager is "Imported1", which defines the entire part.   I have run Import Diagnostics, and there are't any errors listed here.

When the "shell" command fails I select "Entire body" under the Error Diagnostics category, and it is able to identify a problem face, tagged "Failed to offset or face could not be deleted".  This is a convex, compound-curved face is on the exterior of the part and would remain unchanged by the shelling operation, although the interior shell surface would of course be referenced off of this face.  The minimum radius of curvature of this face appears to be about 1/32", and after reviewing the troubleshooting tips, it sounds like this is a problem, but I don't understand it.  If I make a cube and fillet one edge of it to 1/32", I am able to shell the part to 1/16" thickness from another face without any trouble.  So why is SW balking on this case?

The big problem of course is that it's very difficult to eliminate this problem face (and there are probably other problem faces, too) because everything is rolled up inside the "imported geometry" feature.

Again, sorry I can't attach the actual part here.  I'd be grateful for any general tips you could provide though.