I ran a few dozen 6061 parts on a new to me 1994 vf3 last week and I was having trouble with the x or y axes over traveling on higher feed rates. I had a trapezoid shaped pocket with acute angles in the corners and roughed it out with a 3/4 end mill, then cleaned up the corners with a 1/2, first by taking .2 doc climb cuts at 125 ipm, then finishing it with the 1/2, .005 cleanup. By feed holding after each op i narrowed the problem to the corners during the .2 doc cuts, it would leave .015 or so deep gouges at the end of travel. When I single blocked through it was fine, and changing the feed to 40ipm fixed it.
I thought it might be cutter deflection, but it was at the end of travel where the tool was cutting air and it did the same thing cutting polyurethane foam.
I searched the forums a bunch and there was talk of a parameter for maximum corner rounding but I think my machine does not have that, all I can find are servo parameters that I am hesitant to mess with.
All other tool path seemed ok, I ran the 3/4 at 80-100 ipm. Also, I re made the tool path in sprut cam with circular lead in and lead out and it still left a big mark at the end with high feed rates ( well higher, anything over 40).
One thing I noticed was a little groaning/ buzzing of I think the x while stationary. Loading the axis a bit by pushing on the table quiets things. Seems to just be dithering a bit between encoder counts, probably not a big deal.