Hi Tony, it is a bug, it happens specifically if you have a helix with 7 twists in it.

It happens that the sweep tests at 7 spots along the surface to see if the generated surface is coincident with the sweep profile at that spot, to see whether it needs further refinement or not. It so happens that the flat surface you show there actually meets that testing.

Please see this thread: http://moi3d.com/forum/index.php?webtag=MOI&msg=1263.1
for a workaround.

- Michael

Or sorry - it is actually a 6 revolution helix that has the problem, that happens to have the exact arrangement at 7 spots along it which fools it into thinking that flat thing is ok.

But still that link shows how you can get it done by positioning the profile at a slightly different spot for this particular thing.

- Michael

Thanks, that explains it ;-)

Is there a list of these known bugs that I should have checked?

Hi Tony, no not really, this is on my list of things that I've got here to fix up but I don't have that list set up on the web right now.

- Michael

No problem - just wanted to make sure I wasn't taking you away from V2 when I didn't need to :-)

Hay me botham and going to visit this site first time.

Hey bothem and welcome!.........um, but what are you doing in this thread ? you could just start a new thread introducing yourself that would be ok too!

Cheers