Re: Warm left/rear bearing

Steve Wells


Since they are not new bearings(no run in), You can run it with a chuck on it

To check temperature settings, that might change the front bearing temp.

There are many variables in the “ideal” temperatures you will see.

One to keep in mind is at, what ambient temperature did you set the clearance?

“ideal” would probably be 68 degrees, but who has that ability in their home shop,

Not me…😊 There is an expansion ratio/for spindle/bearing temp increase. Visualize

a modern precision bearing fit, to expand about .001-0.0015 we try to raise the bearing inner race temperature

a 100 degrees F or so, trying not to exceed about 200F, these vary by manufacture.

I just tested a set 2 days ago, I had the spindle at 56F and the old inner race slipped on at 130.

I ran the new ones up to 190 and had plenty of time to set my bearings flush with spacers.

Long story short, keep checking the temperatures as the environment changes. I’m

Not sure of your speeds but 1800 rpm is probably the upper limited long run speed.

550sfm is probably a safe running number. With synthetic 650sfm. 85 to 115F sounds fine

To me, but that is relevant to load and speed. For now I wouldn’t exceed much more than

60 or 70F rise until you test loading with a chuck and turning/cutting loads. Also back off the take-up nut,

and set it with a warm bearing to see if it changes the running temperature. You can replace the thrust

washer with a needle roller bearing set and not have to contend with that.

Ted may remember the upper temperature limit, I have always been ok with 140,

depending on how heavy I’m cutting.






From: <> On Behalf Of motopreserveshop
Sent: Saturday, February 13, 2021 11:20 AM
Subject: Re: [SouthBendLathe] Warm left/rear bearing


Ok. She’s button back up and I’m not exactly sure what to think. I will say it runs quieter. And clearly I needed to address the spindle bearing play.


GOOD:  She’s now within spec (best I could get for a .0005 indicator). I’ll check again tomorrow - a tenth indicator arrives later tonight. 


BAD (?) The small bearing is still running warmer than the large (front). I ran it for about 30 minutes on the fastest speed using the large step pulley (3rd fastest speed of 6). It measured at a peak of 118f. And then actually leveled and dipped down to 113f. The entire time the large (front) bearing ran at around 84f. 


Not really sure where this leaves me. I’m certainly glad I got the spindles in spec. And I’m still below the 140f zone that was mentioned earlier in the thread. 


Am I way off here, or is she running as she should?


Thanks for helping me get this far!



On Feb 12, 2021, at 3:15 PM, Steve Wells <wswells@...> wrote:


Here is a new set of felt oilers standing in the wells.

And another with the wires in, ready for the spindle.

What is the serial number of you lathe, I think the “black Plastic”

Comment was my old age…lol that would have to be the fiber washer.

My 10L is a 1968 Tool room and has the fiber washer.






From: <> On Behalf Of motopreserveshop
Sent: Friday, February 12, 2021 9:55 AM
Subject: Re: [SouthBendLathe] Warm left/rear bearing


Once again, really appreciate all the help. I think I’m on the final leg of my adventure (for now!). Few final questions...

1. The brass capillary tubes are almost spot on .1 proud of the surface, so those look great. 

2. When I removed the spindle the capillary wicks were below the surface by aprox 1/4”. In fact, the top of the wick was almost exactly in line with the hole used to insert the wire for holding. Almost as if the wire was removed and they never popped up after installing the spindle and pulling the wire. This seems bad - and would leave the spindle without direct wick contact. Hoping this may have been part of the binding issue. 

3. All oil passages now seem to be clear. I hadn’t noticed the breather also intersected the lower passage. Thanks for pointing that out. 

4. The washer that has always been installed on the take-up collar/split nut is not a pinned “fiber washer,” as I always see referenced. It is merely a very thin shim-style steel washer.  I measure it at .0085. Also, my take up nut doesn’t not have a recess for a pin - maybe this spindle is a different vintage than I normally see referenced?  Is this thin washer a problem?

5. I read an old 10L rebuild thread by Steve that mentions a “black plastic flat washer” in the section about adding super lube to the pulley. I couldn’t see one in the thread photos - and I can’t find one anywhere on my headstock/spindle. Can someone tell me where to look, or whether this is another variation for my era lathe (mid-50’s)?

thanks again!


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