Eagle grinder spindle and way lube? What would you do?

I'm rebuilding a small manual grinder - an Eagle Mk3 W. Got nearly all of the scraping work done and I'm looking for advice on a couple of bits.

Despite sitting under a tarp for 10 years the spindle turns nice and smooth by hand (I had to cut the rock-hard belt off first) so I pulled the rear cover and found the grease was still greasy - no dried out hard lumps or dirt but the grease is very yellow. There's a grease cup that just dumps grease into the cavity behind the bearing so it's stuffed full.



I cleaned out all the yellow grease and the stuff that is in the bearing is more liquid and brown colour., more like regular grease colour.



What I'm wondering is if the yellow grease is brown grease that has started drying out, or if the brown grease is yellow grease that's changed colour from rust or water or something? What do we think? Tag specifies castrol Spheerol AP1, which you can't get though you can get AP2 so I'll use that.

I levered up on the rear of the spindle with a small wooden stick in the gap and got .0003" radial play with the machine stone cold. Does that seem reasonable?

With the wheel off I can get 5 thou end float in the bearings. If I fit a spacer in place of the wheel and pull the nut up the end-float disappears. So it seems to me that the rear bearing is floating and the front bearing pre-load is actually set by the wheel nut. Does that seem reasonable? Seems a rather odd arrangement to me.

I'm rather loathe to pull the spindle and disturb the bearings without good cause. What would you do? Grease them with fresh grease and see how it grinds or strip it out and clean the lot up?

Last question - the tag specifies Castrol Magna ZA for the slideways. I can't find any data on that. I have some regular way oil but it's quite heavy and I'm concerned that it will be slow to trickle down the galleys to the ways. The grinder has an odd arrangement that seems like you travel the table to each end and fill an open trough from an oil can. I don't want to ruin all my scraping work so can anyone help with the spec for that oil. Options for modern Castrol seem to be ISO32, 68, 150, 220. What weight oil would normally be used for a manual grinder?

Cheers for any help.
Pete.

Just following up on my own query here for anyone doing a future search:

I put in a query to Castrol Technical enquiries and they replied saying that Magna ZA was a very old classification of 10 weight oil. I found it difficult to believe that the ways should have ISO10 oil on them but after doing some experiments I found that the peculiar method for oiling the table ways didn't allow regular way oil to travel to them - it was still sitting in the delivery channel weeks later!

So, if you have an Eagle grinder and it specifies Magna ZA, use ISO 10 oil. I have some Morlina 10BL spindle oil so I use that and make sure to replenish it regularly.

BTW my spindle bearings were totally shot. Grinding anything produced a fish-scale finish so I replaced them with metric angular contact bearings and used AP2 grease. I found that the spindle bearings were indeed clamped up by tightening the wheel hub nut. Seemed a bit unusual but there you have it - never run an Eagle grinder without the wheel hub tightened.

I would grease it and run it, see how it grinds, tighten the the pre load if it turns with one hand, if it goes tight back off an 1/16 or 1/8 back if that is still in the go direction past from where you startrd.

Good it put an indicatior on the spindle tube to be sure what is the bearing slack ,and what is the whole head movimg.

michiganbuck said:

I would greas it and run it, seehow it grinds, tighten the the pre load if it turns with one hand, if it goes tight back off an 1/16 or 1/8 back if that is still in the go direction past from where you startrd.

Good it put an indicatior on the spindle tube to be sure what is the bearing slack ,and what is the whold head movimg.

Click to expand...

Ah, I'm not sure I explained myself too well. The OD ring of the bearings are clamped by the end cover, the ID by the wheel nut so the bearings are face to face and the pre-load is whatever is inherent to the pair.

QT machine ref:[the ball races consisted of two opposed angular contact ball bearings behind the wheel with a single deep groove ball bearing at the drive pulley (rear) end. Interestingly, if the angular contact bearings are dismantled (they push apart) an owner reports that they can be revived by polishing the races lightly with diamond paste, fitting new balls and]

This kind of sounds like the bearings pocket is sich that a spacer is made to allow preload when it is made tight with the end cover so if mine I would not tear it down and try to find a schmatcc of the spindle to better understand it.

would not try this-> they can be revived by polishing the races lightly with diamond paste, fitting new balls and]

michiganbuck said:

QT machine ref:[the ball races consisted of two opposed angular contact ball bearings behind the wheel with a single deep groove ball bearing at the drive pulley (rear) end. Interestingly, if the angular contact bearings are dismantled (they push apart) an owner reports that they can be revived by polishing the races lightly with diamond paste, fitting new balls and]

The kind of sounds like the bearings pocket is sich that a spacer is made to allow preload when it is made tight with the end cover so if mine I would not tear it down and try to find a schmatcc if the spindle to better understand it.

would not try this-> they can be revived by polishing the races lightly with diamond paste, fitting new balls and]

Click to expand...

There must be at least three iterations of bearings for the Eagle grinder. I know a guy who has just (yesterday) finished rebuilding one (a Mk1) and it's fitted with taper roller bearings. My Mk3 has these bearings fitted and they cannot be disassembled unless you find a way to expand the outer race 15 thou.



Just for kicks I put one in my press and it took a couple of tons to press it apart, trashing both races in the process.



I imagine that the ones referred to on the Lathes website must be and earlier type of angular contact like the one in my drill press spindle, which does indeed come apart easily as the balls just run in two quarter-grooves rather than radial grooves that are shallower one side.

If the grinder is still together why not clean it up, grease it and take it for a trial grind? Don't know what your requirements are for this grinder but it may meet minimum for accuracy and surface finish. That would allow you to work with it while deciding whether you really want to do a full rebuild. If a trial grind shows the bearings are indeed shot that will help you decide whether to use as-is. Making a decision based upon a static visual is speculation and you'll always wonder if it truly needed it or not. To me, better to have a running machine than another project in progress.

AD Design said:

If the grinder is still together why not clean it up, grease it and take it for a trial grind? Don't know what your requirements are for this grinder but it may meet minimum for accuracy and surface finish. That would allow you to work with it while deciding whether you really want to do a full rebuild. If a trial grind shows the bearings are indeed shot that will help you decide whether to use as-is. Making a decision based upon a static visual is speculation and you'll always wonder if it truly needed it or not. To me, better to have a running machine than another project in progress.

Click to expand...

All that is done mate, machine is all stripped, fully re-scraped, re-built, new bearings, new motor and strip and paint. I mainly wanted to post a follow-up about the outdated way oil spec for others to find in the future.

Here's a before and after, not only of the machine but grinding examples with original bearings and replacements:





Grind example before and after bearing change on same part:

Beautiful job well done.

Nice, looks so much better and the grind looks good too. Definitely worth the effort. You work quickly.