Hi adx, circles and ellipses will end up as what is known as a "rational" spline in the DXF file, where it has an additional weight value assigned for each control point. It sounds like your target application may not fully support this type of spline curve.

But I'd like to check to see if there is any bug in writing the DXF file, could you please send me one of the files that is not working right? You can e-mail it to me at moi@moi3d.com .

For AI export - AI doesn't actually support exact arcs or ellipses, or rational splines, it only supports bezier curves. So when you do an AI export MoI has to approximate some kinds of curves by a type of refitting process. Right now this is done to a tolerance of 0.05 units, so if you have curves that are pretty small, they will get approximated rather roughly.

If you could send me a sample .3dm and .ai file for that problem as well, I could see if I can fix that up to work better.

- Michael