Running it at 25KHz, driver test ok.. Really strange the way the motors behave at low feed rates, almost a grinding noise from the motors and they stutter like crazy.. As soon as I put the motors in rapid (G0) they seem to 'kick' out of the stuttering and rough noise and run really smooth with no loss of steps..

Have checked and re-checked everything I can think of, mechanically the z and y are slick and move very freely. Can pop a 6mm spanner on the rear shaft of the motors and turn them by hand with no effort so the problem does not seem to be there.. Even when under power at low feed rates, when they are stuttering, I have tried gripping the ball screws to see if I can slow them down, but I cant so does not seem to be a loss of torque (or I am as weak as a soggy digestive) and the motors are running cool.. Have a spare axis on the board (with an on board driver) and have tried swapping the the motors around but get the same result..

Am at a complete loss as to what is happening here..

Any ideas anyone? Or maybe you can lend me a bigger hammer...?

Steve...