Geometry gets distorted when applying shell modifier and extrude.

[krislevin]

I get very weird effects of distortion on a mesh while extruding it or applying a shell modifier. I have imported this from Blender. I have fixed the normals as you see with edit normals, and they are perfectly aligned, but I get really bad geometry while doing this. It seems the polygons go to different directions as you see in the image.

here are the normals

and here is what I´m getting while applying shell or extrude. The polygons go haywire at all directions sort of and gets distorted.

It´s well welded and should not have these problems. I don´t know what to make of it. 

[krislevin · Accepted solution]

The issue has been resolved by Autodesk Support group. It was a hard nut to crack. I tried everything from Edit Normals to x-form to smoothing groups. The problem was that it was an import from Blender and due to Non Uniform Scale the normals got distorted. It took almost a whole day to resolve. Not an easy task. If you have problems with your normals I recommend EDIT NORMALS modifier and Xform. Anyways, that was it! Thanks!

[FHull]

I've had this happen too - to a native 3dsMax Cylinder with and edit poly modifier and shell applied - it seems to apply barrel type distortion to the cylinder. Converting the cylinder to a poly & then deleting the top polygon followed by a shell mod  produces the same distortion. 3DS Max 2025

[jibijib]

Not had this, but I always use Reset XForm, which seems to fix everything.

Creating a cube and then attaching troublesome objects to it does the same - it just gets rid of un-needed and confused meta data that may exist on the object from an import. Any unwelded vertices will give problems in shell also.