Originally Posted by
CL_MotoTech
That's a commonly discussed issue. There are more than a few methods used to tighten them up. Most just make a washer or damper that goes inside the bearing housing and apply force either against the interior walls of the housing or against the top of the pulley. Hoss has drawings for the damper.
I am now running tapered roller bearings in my machine after having had the AC bearings in for my belt upgrade (6k spindle). They are just as quit, easier to adjust, andrun just as cool. Once I got everything broken in and adjusted they have stayed perfect. I do think they take a little longer on spindle warm up though, they are bigger bearings with more surface area and they transfer heat to the mill more effectively.