That's likely a display mesh approximation limitation, if you export it (with a forced divided larger than at 2 or less), those arcs seems correctly evaluated.
You can change the mesh angle display in the display option, but even with a tiny angle it wont be as good as the mesh export.

Also if you want a more accurate display, you can maybe rebuild the arc (rebuild command here with 10 points), that should trick the mesher.
(I'm not sure if you still have a perfect math arc doing so ?)

Hi sos, yes like PaQ writes above that's just a display artifact. It's best to just ignore it.

Also some previous discussion here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=10950.2

- Michael

This makes tons of sense. Thank you.

Steve

Hi sos,
I have been a Firefox user and member of the Moi3D forum for many years. I have never encountered any problems when communicating, or when sending images or files as attachments. I therefore don't think the problem is with Firefox.