I bought new bearings for the ball screws on my mill, SKF 7204 BECBP.
http://www.skf.com/skf/productcatalo...did=1230020204

I have read conflicting information on how to install them.
It appears the best way would be installing them back to back, but I have read the inner rings should be clamped tight and also read the outer rings should be clamped tight when there back to back.

I am not sure I understand the proload either and can't decipher what it is form the SKF website.

This is what I think I need to do, find what the preload is (weight) and measure the defection of the outer race when this weight is placed on the bearing.

Take this measurement X 2 and shim between the races of the two bearings and clamp tight the inner rings and I will have the correct preload.

Do I have this right.
How do I find the preload

Your help is greatly appreciated,
Bruce