What lubricating products should I be using for a watchmakers lathe?

[GregG]

I'm assuming you mean for the front bearing only since the rear one has no hole on the inside wall of the bearing?  Or am I not understanding fully?

[rjenkinsgb]

11 hours ago, GregG said:

So the entire rear bearing spins.  The keyway pin, and everything connected to it, up to the split metal ring, all spins.

That's the inner part of the bearing!

The key pin shows it is intended to engage the key slot on the spindle and turn with it.

[edit - accidental duplication].

 

Edited March 15 by rjenkinsgb

[GregG]

So I've got the entire thing reassembled.  I don't think the PTFE was cutting it for making the slide assembly and tailstock lever run smoothly, so I still coated things in some oil.  But I didn't do a very good job of making the application even and consistent. 

There are some spots that look good, and some spots that have small blobs of oil. Exactly how much oil do I need on these parts, and what is a good way to get an even application?  I was thinking one of those foam paint brushes would probably give an even coat and it could easily get into crevices.

Edited March 16 by GregG

[GregG]

I also purchased 5mm belt.  Is this too big for the pulley, and should I go down to 3mm?

[Neverenoughwatches]

1 hour ago, GregG said:

I also purchased 5mm belt.  Is this too big for the pulley, and should I go down to 3mm?

I would think the key points are, that it spins the pulley and doesn't slip either there or at the drive, and not so much tension that the bearings are strained. It does actually look too thick !

Edited March 16 by Neverenoughwatches

[Dell]

Sorry can’t help as I use Optibelt 5mm X 3mm the only drawback is the headstock has to come apart to fit it.

https://simplybearings.co.uk/shop/p680015/Optibelt-VB-5x600-Li-Cogged-Classical-5mm-Wide-3mm-Deep-V-Belt/product_info.html?backstep=1

[caseback]

1 hour ago, GregG said:

I also purchased 5mm belt.  Is this too big for the pulley, and should I go down to 3mm?

Fits nicely in the v-groove. I don't see why you should use a thinner belt, unless this is to big for the pulley on the motor..

[GregG]

33 minutes ago, Neverenoughwatches said:

I would think the key points are, that it spins the pulley and doesn't slip either there or at the drive, and not so much tension that the bearings are strained. It does actually look too thick !

And how do you determine the proper tension?  I am currently using a bench grinder that I removed the grinding wheels from.  I 3D printed a copy of the pulley from the lathe and put it on the grinder.  Alone, the grinder is actually pretty quiet, but things get noisy when trying to run everything together.  The belt wobbles a bit, even though the tension on the belt is pretty high.

I'm thinking it might be due to the belt width.  I don't think the belt is supple enough at that thickness to be able to curve as tightly as needed without fighting back a bit.

[Neverenoughwatches]

1 hour ago, GregG said:

And how do you determine the proper tension?  I am currently using a bench grinder that I removed the grinding wheels from.  I 3D printed a copy of the pulley from the lathe and put it on the grinder.  Alone, the grinder is actually pretty quiet, but things get noisy when trying to run everything together.  The belt wobbles a bit, even though the tension on the belt is pretty high.

I'm thinking it might be due to the belt width.  I don't think the belt is supple enough at that thickness to be able to curve as tightly as needed without fighting back a bit.

I'm far from any expert in lathes Greg, my own trade is different but I do and have used a lot of bench equipment. So with my 2 lathes, I tension the belts until they don't slip and then a touch more. So with a thick belt you would set them to a non slip and that extra touch could be too much on the bearings over time. A thinner belt would have more adjustability providing it still grips the pulleys.

[Jon]

On 3/16/2025 at 4:53 PM, GregG said:

And how do you determine the proper tension?

Just enough tension that if you were turning a piece of rod, the band won't slip. I use a counter pulley with my set up, so I adjust the tension as little as possible for the work I'm doing. I find the counter pulley keeps up the torque when turning at quite low speeds. when not using the lathe move the band so there is no tension, so when you start her up next time there is lubricant all around the spindle. Personally, I turn the pulley by hand to begin with and add the oil then, also on my counter-shaft. I use ISO 22 Airline oil from Toolstation. It's about 8 quid for a litre. Pretty much the same viscosity as really thin engine oil.

I found this oil hits the sweet spot on my WW bed 8 mm Boley and Leinen lathe 

I use the same oil when honing screwdrivers and the like

 

[LittleWatchShop]

On 3/16/2025 at 9:58 AM, GregG said:

I also purchased 5mm belt.  Is this too big for the pulley, and should I go down to 3mm?

For a long time, I have been using 3mm TPU 3D printer filament on all (8) of my WW lathes.