10EE spindle rear bearing replacement study, old style double row angular

I made a new thread just for the rear bearing

I received the 4 different 5210 bearings. The A5210 is a roller bearing, no good. The 5210 WA has a notch on the inner race and has a much less sturdy retainer so it is obviously not suitable. The 5210(max) and the 5510(no suffix) are identical except for the the shield on one side of the 5510, and are similar to the one out of my lathe. They are so identical that the 5210 unshielded has the grooves for the shields on both sides of the outer race. The 5510 has 5210 on the inner race and then 5510 etched on the shield. That seems to be the ND standard for the shielded version of bearings.

The first two pictures are the one out of the lathe. Note the 12xx laser etched on the outer race front, and the "3" on the inner and outer race back. The 5210(max) does not have these markings.

The second two pictures are the 5210(max) and are exactly like the 5510. Note the "GT" on the inner race is after the USA, not after the 5210, Also, it is obviously newer as it has "NDH" (New Departure Hyatt) vs New Departure. The "Made in the USA" is the same. The back side does not have the "3" on it.

I cannot find any information on the meaning of GT.

Any thoughts?

This is the one out of my lathe when I pulled the spindle

It has 12XX then 3 on the outer race. It is original I suspect.

My brand new old stock EE spindle bearings are in red ND boxes
The 5210 bearing has the 2 3's on the back and 13XX where yours has 21XX.
The 13XX is marked by hand on the box label.
The box is labeled 5210X3031A the 5210 is a larger type size than the X3031A.

Bill

I have worked on a few grinder spindles. My Okomoto has 2 duplex pairs. The back pair has the inner races clamped and the outer races a slip fit in the housing. Looking at Cal's pix in your other thread, I would say that your machine has the same arrangement. The outer race needs to be a slip fit not a press fit in the casting.

Some spindles have needed several assemble, pull it apart, look for burrs, reassemble in another orientation cycles to get very low cyclic runout.

Every surface contacting bearings needs to be carefully stoned with a fine India stone wet in mineral spirits to remove any burrs. It doesn't take much of a burr to give clamping and runout problems.

Advice noted. When I get back to the spindle I will start with a stone.

I got out the 5210ZZ that I have for when I need to replace the bearings (I thought I needed to at one time and bought a set from General Bearings Company in LA) and all it has is "5210ZZ" "SNR" and "F35". SNR is the maker and I expect the F35 to be a production code. I can't find an indication of the fill notch on the bearings.