When I took a tour of the Starrett plant in Athol a few years ago, I actually saw them doing this.....
A row of guys sitting at benches, with a geared "speeder" setup they can clamp a micrometer in and turn the spindle quickly. They apply some very watery (though I assume it's really thin oil, not water) lapping compound, spin the spindle, test the "feel," take out the spindle and bang it on a lead block if it feels slightly mis-aligned...repeat until they're satisfied. They are FAST -- no more than a couple minutes a micrometer, as I recall. But they are truly hand-fitted. I would hesitate to do it myself. Those guys have had a lot of practice.
Try to make a living, not a killing. -- Utah Phillips
Don't believe everything you know. -- Bumper sticker
Everybody is ignorant, only on different subjects. -- Will Rogers
Law of Logical Argument - Anything is possible if you don't know what you are talking about.