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Lathe bearings and lubrication

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Forum topic by Andybb posted 02-08-2018 12:21 AM 350 views 0 times favorited 13 replies Add to Favorites Watch
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Andybb

1017 posts in 627 days


02-08-2018 12:21 AM

Just rebuilt a vintage lathe and replaced the only real bearing it has. In addition to being over 50 years old I originally thought that the old bearing was worn and that’s why it spun in place but the new one spins also and I’ve been told that is normal. So, does that need to be lubricated somehow, and with what?

I understand that these brass bearing surfaces should be lubricated with motor oil but not sure how often. Every use? Every 1/2 hr?

Thanks in advance.

-- Andy - Seattle USA


13 replies so far

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Woodknack

11772 posts in 2403 days


#1 posted 02-08-2018 12:24 AM

On my old lathe I occasionally put the back of my hand on the headstock and if it starts feeling warm I add oil. Maybe every 15 minutes.

I’m not clear on the bearing question but it’s possible someone replaced an old bearing with one slightly too small. Does it have any wiggle room?

-- Rick M, http://thewoodknack.blogspot.com/

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Andybb

1017 posts in 627 days


#2 posted 02-08-2018 12:44 AM


On my old lathe I occasionally put the back of my hand on the headstock and if it starts feeling warm I add oil. Maybe every 15 minutes.

I m not clear on the bearing question but it s possible someone replaced an old bearing with one slightly too small. Does it have any wiggle room?

- Rick_M


Thanks Rick.

No wiggle room. I was told it’s supposed to be able to spin freely. The headstock has a brass bearing surface that it rides in so I guess I’ll just use the same motor oil application.

I noticed the heat you are referring to. Just wasn’t sure if I should be doing it every few minutes or so.

The tool and I are just getting acquainted.

-- Andy - Seattle USA

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Woodknack

11772 posts in 2403 days


#3 posted 02-08-2018 01:12 AM

The inside of the bearing should spin, not the outside.no lubrication is necessary on a sealed bearing.

-- Rick M, http://thewoodknack.blogspot.com/

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Andybb

1017 posts in 627 days


#4 posted 02-08-2018 02:03 AM

The inside does spin. But when pressure is applied to it it spins also. I was told by a guy who has one that’s why they use a “thrust” bearing, and it was listed that way in the catalog. It had to be packed like an automotive wheel bearing. It’s not sealed. That way, when pressure is applied via the tailstock it also rotates on the same ball bearings as the shaft. So I’m thinking either dry lube or motor oil. I opted to start with motor oil since that’s what goes in the other holes and I don’t think they had graphite dry lube in 1943. It doesn’t seem to heat up.

-- Andy - Seattle USA

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Woodknack

11772 posts in 2403 days


#5 posted 02-08-2018 04:00 AM

So it’s a thrust ball bearing? Those are designed for axial loads only, not radial like you find on a lathe. It’s out of my experience level, I don’t understand how that would work. Maybe someone else can advise you better. Also, looking up that lathe again, the other bearing is a self lubricating bronze bearing meaning you don’t need to oil it.

Good article on bearing types

This is a thrust ball bearing

-- Rick M, http://thewoodknack.blogspot.com/

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Woodknack

11772 posts in 2403 days


#6 posted 02-08-2018 08:45 PM

After thinking about it I realized that the front half of that bearing will spin and that will be normal. I had assumed it would be a regular ball bearing and it threw me. Doesn’t appear to be a way to lubricate it so I assume it relies on grease, unless the headstock has an oil reservoir.

Are there two bronze bearings inside? Front and back, or just the one in the back? I still don’t understand why they designed it that way.

-- Rick M, http://thewoodknack.blogspot.com/

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MrUnix

6764 posts in 2222 days


#7 posted 02-08-2018 09:05 PM

Are there two bronze bearings inside? Front and back, or just the one in the back? I still don t understand why they designed it that way.
- Rick_M

The spindle rides on the two bronze bearings (front and back), which provide radial support for the spindle. The thrust bearing is to provide axial support from the force exerted from the tailstock ram pushing the workpiece into the headstock. It’s a pretty typical design from that era – for example, it’s the same as on my old Delta and very similar to my 1936 South Bend. The bronze bearings have oil holes above them, so they are designed to be lubricated from there. Typically with that type of configuration, you would have oil cups fitted to provide a reservoir for the oil.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

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Andybb

1017 posts in 627 days


#8 posted 02-08-2018 09:11 PM

Yes. 2 bronze “bearing surfaces” front and back with oil holes.

-- Andy - Seattle USA

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Woodknack

11772 posts in 2403 days


#9 posted 02-08-2018 09:33 PM

Ah, you only showed one oil weep hole. Do the weep holes go all the way through to the spindle? The catalog says they are self lubricating. If you do lubricate them, light machine oil is generally recommended, something 15-17W. 3 in One oil qualifies. And I think sewing machine oil is the same thing. I’m told you’re not supposed to use motor oil with detergents but on my GP I use a motor oil thinned with kerosene and it seems to work fine. Although that lathe is more for show.


The spindle rides on the two bronze bearings (front and back), which provide radial support for the spindle. The thrust bearing is to provide axial support from the force exerted from the tailstock ram pushing the workpiece into the headstock. It s a pretty typical design from that era – for example, it s the same as on my old Delta and very similar to my 1936 South Bend. The bronze bearings have oil holes above them, so they are designed to be lubricated from there. Typically with that type of configuration, you would have oil cups fitted to provide a reservoir for the oil.

Cheers,
Brad

- MrUnix


I have a 40’s era Delta and it has tapered roller bearings which handle both axial and radial loads very well. A regular ball bearing will handle axial load about as well as a thrust ball bearing, or they could have just machined a taper into the front bronze bearing that would handle both axial and radial loads, that’s how my GP is built. The pressure from the tailstock on a small lathe is relatively small, it doesn’t take much. It’s just not a design I’ve seen before and it took me a minute to process. It was during the time when companies were transitioning from plain bearings to ball bearings so no doubt some experimenting was going on.

-- Rick M, http://thewoodknack.blogspot.com/

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Woodknack

11772 posts in 2403 days


#10 posted 02-08-2018 09:34 PM

I’m glad you are posting about this Andy, it’s interesting to see how these machines evolved over time.

-- Rick M, http://thewoodknack.blogspot.com/

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MrUnix

6764 posts in 2222 days


#11 posted 02-08-2018 09:55 PM

Here are the parts from my 1949 Delta – note; there are two bronze bushings even though only one is shown in the picture:


(picture obtained from OWWM)

The only real difference between the two is that on the Delta, the headstock acts as the oil reservoir instead of having oil fill holes above each bushing. And when using bushings instead of ball bearings for the radial load, there is nothing to provide axial support other than metal on metal – which is why those thrust bearings are used.

Also worth mentioning is that when properly lubricated, bronze bushings are superior to, and will last significantly longer, than ball bearings. The down side is that if you don’t keep them properly lubricated, they will tear themselves up pretty quick and are a PITA to replace.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

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Woodknack

11772 posts in 2403 days


#12 posted 02-08-2018 09:59 PM

My Delta headstock also serves as a reservoir.

Bushings have some advantages, but also disadvantages.

-- Rick M, http://thewoodknack.blogspot.com/

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Andybb

1017 posts in 627 days


#13 posted 02-08-2018 10:20 PM

Thanks guys.

Brad, I was concerned about frequency of lubrication. Just wondering how often to lube those bushings? Guess I’ll switch to 3 in 1 vs motor oil.

-- Andy - Seattle USA

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