My spindle is pretty close to square (0.1MM out over 20CM on both axes)
What causes this? Should I cut from only one direction for a final facing operation?
Thanks!

If your Spindle is square, make sure the work piece is held down tight! because if it's not on the same plain as the spoil board you will get artifacts like that. Even if the "top" and "bottom" of the work are not parallel you can see this some. Smaller step over will help it be less noticeable.Mikell wrote: My spindle is squared so I don't think it's that, but I'll check again.