Hi Michael,

Thanks for your prompt reply! I tried AutoCAD's 'convert to polyline' before, and it does work as expected - although even straight lines will get some subdivision.

However, I'm happy to report that your hunch regarding 'parameter space tolerance' was spot on! When I imported the separated curves from MoI it even brought in arcs correctly (not as splines), which already made a huge difference for these files. In addition, any free-form splines were now correctly handled as well.

I was able to join the (now) separate segments in AutoCAD and still export them to DXF R12 polyline format without any issues. The exported curves were either pure arcs/circles or finely segmented polylines.

One thing I noticed in AutoCAD is that I wasn't able to 'join' back all the lines without issues. Some parts refused to connect, whereas the same operation was performed without a hitch in QCad.

AutoCAD might be the standard in CAD, but it's those glitches (in addition the odd behavior I was seeing with the imported files) that will prevent me from ever becoming an actual user, I'm afraid. I'm currently using the trial to mimic the behavior my cutting provider was seeing, but looks like our ways will part forever in about 30 days from now ;)

Another solution that worked for me is using Rhino's DXF export using the 'CAM Metric' scheme. It automatically handled arcs/circles, while having control over parametrization of the free-form splines. I prefer this over having MoI handling the conversion, because I can take a completely annotated DWG into Rhino and then export it to DXF at once. That way, the splines and arcs are preserved as long as possible, so any edits can still be done and at the same time, the file size is kept low.

Thanks again for your help!

- Fabien