I now have HydraRaptor controlled by a Python script running on my PC. I decided to test its circle drawing ability in preparation for using it to mill a large hole in the block of material shown in the last post. When I came to refit the pen holder that I made a few weeks ago I noticed it was no longer a good fit. On closer examination it appears to have curled up a bit.
A bit disappointing because I don't like making things twice. Also it doesn't bode well for objects made by FDM, although this was cast rather than extruded.