I built a Blacktoe replica a while ago, although mine was more robust in many ways.
I can tell you that it will not cut aluminum to .020 of an inch.......let alone 2 tenths. You would have to take a million passes anyway. IIts best to just say it won't cut aluminum.
It is only suitable for very light work......if you are expecting to hold .020 inch. Those who might extol its virtues would be using a tape measure to determine accuracy....not a micrometer.
Regardless of what may be said......the chain drive is not 0 backlash, either. If you mounted an indicator against the spindle.......you could deviate it by .125 inch with one finger.
Its a good machine for balsa or other light materials that don't have to be real accurate. I built mine to cut model airplane kits, and it did an acceptable job for that.
I believe you have unreasonable expectations for even mills that cost hundreds of thousands of dollars. .0002 inch is awful small.