Randy, I never did wrap this thread up, so here we go. I installed the new *** 45x75x22mm class P5 unshielded bearings without too much trouble. The unintended press fit of the aluminum belt pulley was fixed so that everything was a "gage-fit" and the pre-load nuts worked like they were supposed to. Noise improvement was noticeable, but there are other sources of noise in the motor, in the toothed belt drive from the motor to the idler pulley, and in the v-belt in the final drive to the spindle. And in the straight cut threading feed gears, too. So I just decided that it was good-enough. BUT, I did find that paying special attention to the belt tensions, and keeping the threading gears free of debris and even using a little grease on the straight cut teeth helped just as much. I was unable to locate a magic bullet.
Lloyd
edit P.S. Almost forgot to mention that I found that with the opposed pair of tapered roller bearings, the preload ended up tighter than I expected, with no measurable axial movement. The bearing preload was established in a few different sessions over the period of a few weeks.
