Controlling servo lag is the likely culprit. What it boils down to is that the positioning accuracy of the machine is compromised due to high feed rates. It takes an extremely high servo update rate to maintain any kind of position control during high feedrate moves. This causes a lateral displacement of the machine table which "offsets" the surface a little bit from the theoretically perfect position. When you recut, approaching from a different angle, or using different feedrates, then the "blended motion" of your previous high feed path is no longer applicable to the new path, so then the gouging occurs as the servo is now positioning a little bit differently than it was before.
All you can really do is to make sure that your servoes are tuned as tight as you can get them, to minimize overshoot. This can make a world of difference.
Then slow down your feedrates until the positioning overlap is acceptable between the two passes.
My 2 cents.
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(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management) |