Hi Michael.

Another splendid explanation as to what is going on here - thank you.

So it looks like ACIS can make nice surfaces, but is apt to throw out a lot of the good work further down the line. I think that may explain why I've noticed changes to (complex-ish) faces of solids when I've done something like join them within ViaCAD.

My question is whether this hugely degrading 'feature' is entirely down to ACIS, or is likely to be some unfortunate error in how ACIS is being implemented? A case of "Snatching defeat from the jaws of victory", if ever I saw it!

http://doc.spatial.com/qref/ACIS/html/modules.html for anyone with an interest and can comprehend it :)



Cheers.
Martin (2).