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ESM-59 spindle bearings

jkycia

Plastic
Joined
Oct 30, 2020
Hello
I am slowly working towards changing my spindle bearings for my ESM-59. I have not done such a thing before, so I could use advice.

There is currently too much vibration (resonances) and it runs a bit loud. The concentricity and runout I think are not very good. Concentricity is about 0.002" to 0.003". For the resonances, I was hoping it was the DC motor. I ran it without the belt and it had resonances. I replaced the bearings on the motor and now it runs great. Now I can clearly hear the noise from the spindle. Before it was coming from everywhere.

I looked at the documentation that came from the previous owner. There is a hand drawn blue print of the headstock. It shows two bearings, one on each end, with an OD of 90mm, ID of 55mm and width of 18 mm. Can anyone confirm that this is the correct size?
Some of my documents are for an ESM59 and some for a DSM-59 so I need to be careful. I could take it apart and really know for sure.
I hoped to order the correct bearings, then take it apart and install to reduce down time.
In my stuff that came with the lathe there was an 40mmx80mmx18mm bearing ABEC1. That concerns me in that it is a different size. Its an ABEC 1 which would not be suitable. So maybe it has nothing to do with the spindle.


Looking at bearings to get, I see this one (see below) (comes in a pair) and not cheap as unfortunately I expected. Does this look like a good (hopefully great) bearing for this application? In the draft I have it does not show any tilt in the contact angle. 15 degrees seems like a good idea, I would set them up to oppose each other I think.



Thanks,

Jan


55BNC10S Nachi high precision Angular pair of Ball Bearings with 15 degrees contact angle and Polyamide resin cage, pair of ball bearings are 2 duplex bearings, bearings are ABEC-7 (P4) quality and made in Japan.

Item: 55BNC10S Nachi Ball Bearings
Type: Nachi Angular Ball Bearings
Cage: Polyamide resin cage
Quality: ABEC-7 (P4 quality)
Dimensions: 55mm x 90mm x 18mm/Metric
Bearing Inner Diameter: 55mm
Bearing Outer Diameter: 90mm
Bearing Width: 18mm
Size: 55 x 90 x 18 mm
Quantity: One Bearing
Dynamic load rating Cr: 56,000 N
Static load rating Cor: 57,500 N
Limiting Speed:
Grease Lubrication: 8,800 RPM
Oil Lubrication: 12,000 RPM
Made in Japan
 
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Here is an update. I decided to measure the runout again. I now see its not so bad. I very gently cleaned the inside of the spindle's taper with a scotch brite pad with the spindle spinning (is that ok for it...maybe if done rarely?) It looked clean before. I used a 1/2" reamer in a collet. I now measured the axial runout (measured with an indicator right at the collet and read 0.0005". That is not bad...could be the collet actually. Then I shifted away from that location by 1" away from the mouth of the collet and measured 0.0015" deviation....yeah...now I see I should have measured 2" away as well since two errors (axial offset and angle error can even cancel at some point if oriented in a certain way.

Well, I still have the resonances. I will avoid those RPMs. I did look at the collet taper in the spindle and there are noticeable bumps at the 4 locations that the collects have slices. I suppose these are ok if I am not closing the collet too much and if they are all the same but does this cause some trouble? Is there anything I should do about these?

Thanks
 
High mileage machines will "grow" ridges in the three spots where the collet, isn't. Obviously nothing grows, the rest of the spindle
bore simply wears. Unless you want to clean that up with a toolpost grinder, leave it alone.

Be careful with the spindle bearings. Hardinge went though a variety of design changes on the machine and it may have an angular
contact pair, with a preload spacer between them in the ID, or it may have an angular contact pair in front, mounted close to each other,
and a radial bearing on the back of the spindle. You will probably destroy the bearings removing them from the headstock so if you
go that route you have to pay the money to finish the job.

If your machine is like mine, the two V-belts can be slipped off the very back of the spindle without removing anything more than
the cover.

The preload nut on the end of the spindle was JESUS tight and took a fair bit of effort to make a special tool and a LARGE wrench to
undo it. This allowed me to slip the spindle and front bearing forward (after undoing the six allen head screws on the front cover)
and pemitted me to get a hypodermic nose grease gun in there, and apply more lube to both front bearings. In my case the lathe
was zero hours but had sat unused for many many years. So the lube helped I think.

1) vibration can be caused by the two V-belts being unmatched. If in doubt buy a new matched set and replace them.

2) vibration can be caused by the large special bearing on the collet closer. Run the machine without that to check. Replace
if needed.
 
Jim, Thanks for the info. The drawing of my headstock shows two bearings. I will see if I can attach this to the posting. I am not experienced with doing that, so we will see if that works. HardingeESM59HeadstockB.jpg If it does not work, I could send it to you if you like.

The previous owner switched it out to a variable speed 1HP DC motor. Its max RPM is 1200RPM. It uses one size 3L belt that I pretty loose. The spindle still has the two same sized pulleys, the motor has only one. I was told 10lbs should deflect by 1"... I can't judge this well but its clearly loose. I tried tightening but the belt is narrow and sits deep in the V groove. So if I make it as tight as I can to still be able roll it over the edge of the motor's pulley, it then falls into the groove and is loose.
I need to make a better setup for holding and adjusting the motor. Then I can tighten it and keep the motor level with the belt on.


My collet closer is a simple tube that I screw tight. It looks balanced. So no bearing.
 
Here are some more pictures. You can see its been heavily modified. There are no gears levers and at the top of the headstock there are holes where probably the oil cups used to be. You can see the smaller special-4-holed nut at the end of the tailstock has been chiseled (previous owner did not use a special tool). You can see the 3L belt sits deep in the V-groove. I do not know if that is ok or not.
LathePictureA_2MP.jpg
LathePictureB_2MP.jpg
LathePictureC_2MP.jpg
 
I'd suggest you try measuring the spindle runout on the nose outside taper up past the slots at a point that looks as clean as possible and not worn yet still on the ground area, if you can find such a spot. That way you don't get any collet error.

Irby
 
Irby
Good point. So I just measured this now. I measure a runout of 0.00045".

I located the indicator at the furthest point from the end.
I used a Mitutoyo digital vertical indicator. I do not have a horizontal one.
I find it tricky to do this measurement but I think I am doing it correctly. I measure a smooth oscillation in value as I slowly rotate a full revolution and the zero is not shifting from one revolution to the next, so I don't think I am getting tricked by a poorly held indicator or surface imperfections.

Jan
 
Somebody has either already changed the spindle bearings, or attempted to, and gave up, based on the condition of the holes on the nut that would be used to undo it.

I seem to recall that I held the tool I made in place with a piece of all-thread, clamped through the spindle, to prevent it from camming out. I also seem to recall that I could not use the spindle lock to hold it the spindle when doing this, I had to put a faceplate on the front of the spindle nose with a bar clamped to it.

I had the largest pipe wrench on the tool when I undid the nut - the tool was a home depot steel pipe coupling with four slots milled in it, and I put four dowel pins in the slot that fit into the holes in the nut. I specifically recall it was 'jesus' tight, as in, "jesus, why did hardinge have to sock that home so hard when they assembled it?"
 
Jim, Yes, I recall reading your old thread for when you you doing it.. You were asking others if you were doing something wrong and that you had checked if the pitch of the thread was right handed as it seemed from the few threads you could see.

In my case, I see the holes are chiseled more on the -to loosen direction- and slightly in the -to tighten direction-. That is a good sign they had changed it. Also I have holes in the top that may have been for the oiling cups. So maybe they changed it out to life time greased bearings from the original oil cup with felt. I have the original brochure and it says both options (oiled and zero maintenance greased ) were available.

Why did Hardinge make it that tight? Can the pulleys over time tighten that nut as they spin? When you re-tighten it, you did not set it to that tight and everything was fine?

The preload for the bearings are just set with the accurate spacing of the shaft and headstock casting?

Jan
 
For yours, I would think yes. It's like an HLVH, there's an inner and outer preload cylinder, so it's just those and the bearings' original setup from the factory. In my case that machine has an angular contact pair (run with both races in contact) in the front, and a radial bearing on the left hand side of the spindle.
 
Hello Group
I replaced the bearings.

Thanks for the help, especially Jim S. for walking me through disassembly and assembly

One thing I wonder about is if I put enough grease in. I know too much grease is the classic mistake. The unit uses two 55x90x18 bearings.
How many cc's of grease would you use? I read somewhere a person said you take the last two numbers of the bearing code number and multiply be 0.3cc. So this is a 7011 bearing. so 11x0.3 is 3.3cc. Before I read that, I was going to put 5 cc in each but that was off of some table and the nearest bearing size I saw on there was a bit larger. Is 3.3 cc too low?
When starting up the spindle, I could hear a slight very light intermittent scraping sound. I ran it at low rpm forward and reverse and I think this seems to have gone away. On another test. I bring it up to max (for this configuration that is 1200 rpm). I did not hear any problems. Now when I bring it up, I hear a sharp high squeak. I stop right away. Did I not put in enough grease? did I not pack it well (I pressed in spots with syringe and rotated by hand many times.

By the way, before my runout was 0.00045" now it is 0.00015". Also, more importantly, it would shift significantly if I pushed on it from the side and now I do not see that. So that part worked out.
 
Correction.. The intermittent high speed squeak is coming from the DC motor. I think the spindle bearing may be working perfectly fine now.
For the motor, I replaced the bearing just before this spindle bearing job, so that new squeak is bit surprising. Maybe it was masked by the spindle noise before, but if so, I am surprised, since I think I would have noticed such a high frequency squeak kick in (whatever the source) and I did not.
 








 
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