[jevs]

I decided I want to get the backlash out of my 1978 Pratt & Whitney Tapemate C retrofit (Fanuc machine basically).

It seems like the backlash is in the ball screws, but I wanted to replace the support bearings also.

There is no info at Fanuc for the part number in the manual, so they said I need to pull the bearings to find the numbers.

Well, I did that and they only have the generic 7204A then hand etched for the rest of the part number.

The numbers look like
7204A DBC9PK
or
7204A DBC9PX

Not sure if that is an x or k?

I gave this info and pics to a bearing house and I guess they sent it off to NSK.

They came back with this part number:
7204A5TRDUHP4Y

When I look these up they are ABEC 7, P4 etc.

https://www.motionindustries.com/pro...p?sku=00114980

This seems like a lot of money for these 47mm bearings. I know bearings can be expensive, but is this reasonable for a 1978 machine? It has single nut NSK ball screws.

I just want to make sure I am not paying too much for an over spec'd bearing. By the time I get done reconditioning two screws and replaced the support bearings I will be $2500 to $3000 in this old machine just for the XY screws and bearings (not including everything else).

I have a lot of time and money in retrofitting it with all new AC motors, drives, full electronics, Mach4, programming time, etc etc, so I am too far into it not to get this backlash out. (~.0030 in Y and ~.0014 in X).

I just want to make sure I need over $800 worth of bearings here.

I am not even positive the old bearings are bad. They are old, but this machine was never in production (came from a university teaching NC programming). I have had it for 14 years myself and it was never really used during this time. I made a couple parts when I initially got it working with Mach 3, but recently I revived the interest again with getting it up on Mach 4 and upgrading the computer and some other stuff.