Hi Zeeflyboy,

You could well be right, the sudden impact... I must say that I always set the Fusion360 lead-in lead-out feed rates the same as the cutting feed rate as I've seen no difference under normal circumstances. I can also try the accel/decel settings in the controller, see if it helps. These were light fast rate passes on an SX3 milling machine, which otherwise gives me a very nice finish. I need to get to the bottom of this. Thanks.

Edward