I'm learning a lot... like you hardly need any torque on the thrust bearing retaining nut on this KMB1. I learned how to make new tab lock washers too since nobody stocks them, but several say they can get them... eventually. I even learned what the X axis is supposed to sound like with good thrust bearings. It never really had any problems, but its sure sounds a lot smoother now. Obviously the bearings were bad.
With new thrust bearings on the Y-Axis its pretty smooth now too, but only for about 7/10 of a turn. Then it pulses. Its actually a lot worse than it was before. Before I could see a little flutter about every 1000 steps or so on the scope, but the machine appeared to move smoothly. I guess the Y-axis thrust bearings were so wore out that it allowed it to move smoother. With new fresh bearings it pulses badly. And no its not a matter of tuning. As near as I can tell the ballscrew is bent and its binding as it turns. That would sure explain the chatter I saw before. Now its unusable.
The bad part is I don't know how to remove the new bearings and save them. The obvious way to pull the bearings pulls the rear bearing apart when you take the housing and bearings off the shaft. So... even if I find a good replacement ballscrew I'll wind up having to chase down another set of bearings too.
Of course I have one piece to make to finish a job that is just a little too big for the little mills.