Thanks for the reply, Gerry.

I have several related issue that I'm trying to solve. Firstly, my cnc router is run by a dsp pendant, instead of mach 3, that has a max file size of 105mb, meaning I have to divide big cutting files into parts. Secondly, my reliefs have some flat faces visible where there is not much detail. I have looked at increasing stl resolution but am trying to avoid making the file sizes larger. I was hoping that by converting straight lines to arcs, I could both reduce file size and smooth out the look of the relief.
I received this advice from the Blender (CAD) forum, but don't have the experience to know if it is possible to implement on deskproto, or any other cam;

If you want smoother cuts on your CNC from an STL file, you need to post process the G-Code.
Here is a script that converts straight-line (g1 cuts) to g2g3 arcs.
LinuxCNC Documentation Wiki: LinesToArcs

Does this make any sense to you? Could it do what I want and reduce my file size and smooth the workpiece. do you think?

Thanks. Chris