I used a procedure very similar to what @cyberreefguru posted here. Except that when calibrating the Y-axis travel, I measured with the scale at both sides of the cutting area, as well as in the center. Unsurprisingly, the measurements in the center equalled the average of the measurements made on each side.
The other thing that I did differently was to jog the rounder-over bit “pointer” precisely into alignment with the hash marks on the ruler scale, and use the high-resolution readouts on the controller to determine its travel-measurement error. That way, I didn’t have to try to eyeball intermediate measurements between the ruler hash marks.
