Hi there,
I usually work in G95 mode (feed per rev) as I'm more used to that in the lathe, and I've not had this problem with G2 or G3. But I'm a bit paranoid and set the F on every non "G0" line as attached. Does this file show the feed problem on your setup?
One thing I did notice just once, Mach3 got the feedrate completely wrong on one line (G1) (much too fast, but not G0 fast), then the next line was extremely slow, after that it was OK. Code was fine as far as I could tell.
Do you still get the problem in G95 mode? Also, I'm not sure how to get a feel for feed per min when turning. Why would you use that in the lathe? If no spindle speed feedback?
Regards,
Woody.