The cutters just had unspecified issues. It was a few years back now so maybe there aren’t problems with arcs anymore.
I have heard that sometimes very flat arcs with huge radius values can cause issues.
I can confirm this.
Some CAM applications cannot handle very large radii. I have had to create a script to track down large radii segments and convert those to polylines. Because all polylines was not an option for this specific client.
I wanted to update this conversation. To answer @Ncik, the parts were never exported as a surface. They were always converted from a surface to lines, arcs, polylines or splines. With many CAM software suites, splines are very problematic and even polylines can cause issues, especially with older versions of SigmaNest or similar. I committed a stretch of time with one of the larger steel suppliers in Seattle to work out the optimal export options. I also spent some time with Rhino support. It adds a few extra steps, but the final solution seems to work good with no issues. I just sent a nested group of parts for cutting and we will see if all processing goes as well as expected. Bottom line is all geometry is converted to lines or arcs only. Rhino has the ability to accomplish this with results within tolerance. Thanks so much to the forum contributors and Rhino. Using this process, there should be no issues, even when sending files to a small company using older software drivers.