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10K Spindle Bearing Temperature Rise: How Much is Too Much?

USNmechanic

Aluminum
Joined
Dec 1, 2016
After trying to sell my 10K for several weeks with no serious offers, I decided it probably wasn't selling for what I though it is worth because it was mounted on a couple sheets of plywood on a floor dolly and it still had years of grime on it. I built a bench out of 2 1/2" x 3" hardwood boards I've had stickered up in my basement for years, and used a 1 1/2" thick pine top that I got from a guy at work. I finished cleaning and reassembling it this weekend, and have decided to keep it :D.

Before:

IMG_7518.jpg

This Morning:

IMG_7655.jpg

I checked the spindle bearing clearance this morning, and found the front bearing has 0.002" clearance and the rear has 0.005". When assembling the headstock, I made sure that the bearing retainer screws were loose and used a torque wrench to tighten the bearing cap bolts to 10 ft lbs based on the rebuild manual's recommendation of using approximately 20 lbs of force and a 6 inch wrench. I then tightened the retainer bolts using just my thumb and forefinger on a stubby flathead screwdriver. The bearings and spindle journals looked flawless when I cleaned them, and the indicator I used is older and not as responsive as I would like, especially in my unheated shop. So reading that too much clearance is better than too little, I decided to run the lathe for an hour at maximum spindle speed and check how the bearings heat up. I used an infrared thermometer to check each bearing temperature every 5 minutes, and below are the results.

Screen Shot 2019-12-01 at 3.10.05 PM.jpg

Does anyone have any experience with how much temperature rise should be expected? Since the temperature rise was almost 35 deg F over the hour on the (tighter) front bearing, I'm nervous to remove any shims, especially from the front bearing. The mass of the headstock is pretty large, and I would assume that a lot of the heat being generated is being wicked away from the bearing and not showing up as an increase in temperature. I definitely don't want to go chasing the spec only to mess something up, especially if I'm not confident in the clearance measurements to begin with. I also didn't notice any significant drop in oil level in either oiler, and the surface finish on the aluminum collars I turned to align the tailstock was excellent.

Any advice would be greatly appreciated as I have no idea if the temperature rise I saw was normal. Thank you!

-Keith
 
Nice lathe.

Usually with bearings like these, you will see a problem where the spindle bogs down or even stops, when run at extended
time at top speed. This is typically accompanied with the bearings getting 'real damn hot.'

That your spindle ran fine at top speed, for an extended time, and the temperature stabilized at a reasonable number, implies
that the setup is in good order.

I've never been able to get plain bearing SB spindles to run at top speed, with the specified clearance, unless I replace the
spindle oil with 0W30 mobil one synthetic engine oil. Otherwise they do tend to bog down and slow up.

I would leave your setup the way it is for now. Some day you might want to slightly reduce the clearances a bit. If the lathe
works well, however, maybe not.
 
Thanks Jim! That advice makes me feel better about leaving it for now. I was mainly concerned that at some point too much clearance could be just as bad as too little. Someday I may remove one layer from the rear shim and repeat the test, and then compare the results. I’ll be sure to post them if I do.


Sent from my iPhone using Tapatalk
 
I am replying to this thread with some measurements that are very different than these, which may be of interest to those doing a search for spindle bearing temperatures.
I have a vintage, lightly used 10R. My temperature rise was MUCH less than the above post.
10 min 10 deg rise
15 min 25 deg rise (deg F)
30 min 32 deg rise
40 min 35 deg rise
Lathe running at max spindle RPM of 700 rpm
 
I am replying to this thread with some measurements that are very different than these, which may be of interest to those doing a search for spindle bearing temperatures.
I have a vintage, lightly used 10R. My temperature rise was MUCH less than the above post.
10 min 10 deg rise
15 min 25 deg rise (deg F)
30 min 32 deg rise
40 min 35 deg rise
Lathe running at max spindle RPM of 700 rpm

Looks almost the same as what the OP got, say you started at 55F, after 40 minutes you would be at 90F. After an hour, the OP reports his front spindle bearing is about 88F.
 








 
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