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cross slide thrust bearing repair

rimcanyon

Diamond
Joined
Sep 28, 2002
Location
Salinas, CA USA
In my experience, the cross slide thrust bearings are often missing balls. They are easily repaired - they take 3/32" balls, which are readily available. Monarch used standard inch dimensions for almost everything, bearings included. Yes you can buy new ones (INA FT-100), but repairing the old ones is often warranted if the flat washers are in good shape or have an unused side and if you're a cheapskate like me.
 
RC has a round dial machine. On my square dial, what I found was the thrust bearings in the friction stem assemblies, the crossslide leadscrew, and the tailstock leadscrew were the same size, an English size as RC said, but not available. I think they were 1/2 inch id.

Two possible repair solutions. I used both. Get a different od but the same id, or use a metric bearing that has a bigger id and turn a sleeve to make the smaller id washer. Since the larger id washer is a slip fit diameter doesn’t matter as long as it is a loose fit.
 
The 5/32" balls are available. My order of 200 will be here this afternoon. The cross-slide leadscrew on my machine with TA uses bearings at the TA end of the screw and another at the dial end. I did confirm that 3/16" will not work at the dial end, as this bearing provides spacing for the dial. The 3/16" bearing pushes it out and leaves a gap between the dial and the spigot that the dial spins in. I've not checked the bearings at the TA end of the screw. The dimensions for the bearing at the dial end are 5/32" thick, by 7/16" ID, by ~7.8" OD. The OD of the cage is 0.905". I think a bigger diameter bearing would work, but the 7/16" matches the OD of the telescoping assembly.

Dave
 








 
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