[Recoil6]

I am in the process of changing my thrust bearings for my Fadal 3016, when I removed the bearings in the X there were NTN 7304B bearings. They where mounted face to face with a shim in between them.
When I removed the Y axis the bearings are different SKF 7304 BECBY and they where mounted back to back with the shim in between bearings.
That struck me as weird, I am guessing at some point the X axis bearings were replaced since if I am not wrong Fadal used SKF but I might be wrong, Also I am unsure on what arrangements the bearings should go, I think they should be the same arrangement on all axis but then again I might be wrong.
Anyone knows what is the correct arrangement for the bearings, is it face to face or back to back? Is it the same orientation for all axis? Thank you!

[ianagos]

I may be wrong but I’m pretty sure they are supposed to be face to face so that way the shin actually adds preload on the bearing once the bearing clamp ring tightens.

[Recoil6]

Thank you ianagos, I think you are right and I think it should be the same arrangement in all axis. I think someone worked on this machine and made a mistake but I can see how it happen. Look at the bearings picture. The inner flange is wider on the back than on the front, it makes more sense to have more contact area for the shim on that side but then again I know there is a difference between mounting face to face or back to back.
Anyhow I hope one of our Fadal gurus can answer that question

[motogomi]

Wider faces of inner races towards each other, shim in between. All axes should be the same.

[Recoil6]

Thank you motogomi, ah! I did not see that one coming. That means the Y axis was correct back to back with the shim in between the wider inner races. I was getting ready to mount the bearings face to face.

[ianagos]

This is how you want them which according to info I have found is face to face

[Recoil6]

Thank you ianagos! You are awesome that makes sense "The stamped outer ring faces are mounted away from each other or are "outboard" when preloaded bearings are used in this manner".
Couldn't be clearer, once more thank you!