CorelCAD :: UNION Fails With Solids Made Entirely From 3D Polylines

FAIL-UNION-3D-Polyline based wedge.dwg...An unusual bug here, and a workaround of sorts. This one is fairly serious and results from attempting a union of a solid with another solid, when one of the solids is created entirely from 3D polylines and is not on a CCS planar axis.

I'll attach the same file twice - once with a bug ( 3D polyline solid ) and once without the bug ( Solid has been modified to include one "normal" polyline face. 

In the middle, a wedge connects the two. Basically, I needed to increase the angle between them by 15 degrees, so slice, polyline around faces and LOFT. Pretty simple and straight forward.  The result was that any attempt of a union with the wedge in the middle results in a failure due to inconsistent faces, and the deletion of the non-polyline solid.

This results in damage to the file, and the operation must be backed out or reloaded.If the middle solid includes ONE normal polyline face, with a repositioned CCS on the face, then no problem. This is a workaround, but only sometimes, however if fixes the problem for both the polyline face and the 3D polyline face.

I've encountered this problem a few times, but it was this project that made it possible to capture it cleanly and understand what was happening. It's a critical bug, but only affects parts made from 3D polylines and LOFT operation, so it's more likely to affect complicated designs.

To see problem, take 3D polyline file and use SOLID UNION on the three ( or middle and one side ) pieces and you'll get an error and part deletion. Try again with the "workaround" file, and you'll see that it works both sides now.

The file with this post is the "broken" one - the middle wedge is a single 3D solid created with LOFT and 3D Polylines.