you may want to take a look at the vernier measurement approach I talked about
in https://forums.maslowcnc.com/t/in-search-of-accurate-measurements
note that the design goal of the machine was toget to ~0.5mm so you are close to
the limit (also look up the ‘sources of errors’ thread about all the possible
things that could contribute to the errors)
right now, you are at the limit of what that calibration method can do, that
doesn’t mean you are going to be that accurate everywhere, so if it really
matters, do a test cut and check the results.
David Lang