Cutting POM/nylon/Delrin ?

kreature wrote:

I mostly get .stl files or other mesh files which are then translated into toolpaths for inner/outer or upper/lower etc.

STL files will always be straight-line segments, as that is what they define.
An STL file is a set of triangular faces, and the CAM simply finds (for example) the point where Z intersects the (XYZ) equation of each facet edge.
The correct process it probably to set G64 to match the STL file creation tolerance, then you should get a good representation of the object modelled (rather than a good representation of the STL file, which isn't actually what you want)