danielcoyle

Are the Bearings you are holding, how they were assembled in the spindle???

If so this will tell you the orientation of the Bearing, different spindles have different bearing orientation, it just depends how the spindle was designed/ made

Holding the bearings in your hand as you are if this is how they were assembled, push in & out on the center of the bearing, holding the outside of the bearing tight together, if the center of the bearing does not move, in/out, then the bearings are either mounted Back/Back or front/front, so the are 3 ways they can be assembled, if there is no movement, they are most likely mounted Back /Back

How to know if they are Back/Back, look at the outer ring of the Bearing, one edge will be thicker than the other side of the Bearing, when they are mounted Back/Back the ( 2 ) thick edges will be facing each other & the ( 2 ) thinner edges will be facing outwards

Most of these spindles have the ( 2 ) Front Bearings facing the same way with the thin edge of the bearing facing outwards, towards the end of your Spindle, the preload is then adjusted at the top of the spindle

If you want a longer life for your spindle bearings, you will need to add rotor grounding, all VFD driven Spindle Bearings have a short life, the voltage build up in the rotor arcs out through the bearings, this causing a short Bearing life