I use Ares as my CAD package. Some dxf files work just fine with the UCCNC CAM function, but some generate an error - "not a valid ACAD200 file".
There are no splines or nurbs that I can see in the dxf file.
I did find out that all blocks must be exploded before exporting to dxf, but that's not enough. It appears that there is some drawing feature that taints the drawing so that it won't work any more.
I've attached two dxf files (renamed to .txt to allow upload). They are the exact same part. I created the 'bad' one first, and it had some blocks that were inserted and then deleted. The good one was created by simply copying all of the entities from the bad drawing to a new drawing.
What do I need to do to create usable dxf files? I'm reporting this as a bug because as far as I can tell I have a valid dxf file that UCCNC can't process correctly.