The lathe measures in 3d to 10 micrometer accuracy by Polar to Rectangular conversion and Spindle Speed calculation in the macros and with the calibration of the probe tip on inner and outer ring surfaces.
Calibration is a main part of the lathe upgrade, which successfully compensates for the offset of the rotational position in XY and for tip offset in XZ using Groove Calibration. An optional small inside circle in the Groove Calibration can compensate for Y axis tip offset, but it has been found to make little improvement. It also has caveats in how the calibration is done.