My lathe setup

[LittleWatchShop]

Here is my setup with copious magnification!  I am now at the point of being dangerous.  Quality tools in the hands of an amateur.

When I was a kid, I would often play with this lathe, but never developed any skill...just had fun turning brass rods.

Edited February 23, 2021 by LittleWatchShop

[Klassiker]

That's the first time I've seen a toothed drive belt in use. Do you have toothed pulleys too?

[Michael1962]

That looks like a standard toothed V-belt. Highly unlikely that the pulleys have teeth as well.

The teeth allow the belt to go around tight turns more easily.

[oldhippy]

They have a better grip. 

[Klassiker]

4 hours ago, Michael1962 said:

more easily

Than what?

4 hours ago, oldhippy said:

better grip

Than what?

[oldhippy]

A  smooth belt 

[jdrichard]

I always use a leather belt, countershaft and a sewing machine motor on my lathes. very quite and plenty of torque.

[jdrichard]

 

[LittleWatchShop]

7 hours ago, Klassiker said:

That's the first time I've seen a toothed drive belt in use. Do you have toothed pulleys too?

No teeth on drive, or headstock.  Just friction.  As I recall...my dad had a leather belt installed back in the day.  Not sure what caused the transition.  It is a very nice belt and will never break--pretty sure of that.

It is quiet.

[Klassiker]

1 hour ago, LittleWatchShop said:

will never break-

You can be very sure of that! The concern I would have with a toothed belt is, they have no stretch in them, like a drive chain. You have a relatively small area of adjustment, outside of which there is either too little tension (slipping) or too much (radial load on the bearings). But If it works for you, then fine!

[LittleWatchShop]

42 minutes ago, Klassiker said:

But If it works for you, then fine!

I admit to being a novice with the lathe.  The tension I have set on the belt is such that it will slip with some amount of resistance.  I will get a feel for this over time and adjust accordingly.

[LittleWatchShop]

6 hours ago, jdrichard said:

I always use a leather belt, countershaft and a sewing machine motor on my lathes. very quite and plenty of torque.

Hmmm...I have an extra sewing machine motor.  Need some pulleys though...will look around.

[Michael1962]

If you have the same tension on either a round leather belt or the toothed V-belt, no more radial load will be exerted on the bearings.

Due to contact area of the V-belt versus a round belt, you will get more power transferred to the lathe before the belt slips under load.

[JohnR725]

Watchmakers are interesting people we adapt and use things from a variety of sources.

One popular method of belts is something that  can be fused together. heat up the ends push them together clean up the access and I never like that as it is really hard to do. But it was popularly sold because you can have any size you want.

Then somebody discovered sewing machine belts. Exactly what's being discussed here the perfect solution other than you have to disassemble lathe to put them on. Even though supposedly they don't scratch they do stretch enough to hold nice and tight they do work really well. About the only downfall that I noticed if you don't use your lathe on a regular basis to keep the belt under tension it stretches. But I doubt you're ever going to see that under normal use.

[LittleWatchShop]

11 hours ago, jdrichard said:

 

Where did you get that BDP (big damn pulley)?  Looks like a fun thing to build.  Got some more lathe stuff coming from Ebay...thinking about doing something similar.

[LittleWatchShop]

Compare and contrast.

I tore down an old Singer today.  This is the belt on the unit compared to the belt I am using on the lathe.

I would say that the Singer belt has no stretch whatsoever.  It is old...granted.  I believe my belt does have some slight stretch...can't say for sure.

[Klassiker]

15 hours ago, LittleWatchShop said:

I will get a feel for this over time and adjust accordingly

With your set-up you can adjust the tension then clamp everything down so it doesn't move. "Slipping with some amount of resistance" is probably about right. That's an engine timing belt, so it won't stretch, ever. it might wear though, or it might wear your pulleys. If you want to run on one of those smaller pulleys you will have to readjust for tension and alignment. The Singer v-belt might be the better option, but you have to dismantle everything again to try it!

[jdrichard]

On 2/24/2021 at 7:34 PM, LittleWatchShop said:

Where did you get that BDP (big damn pulley)?  Looks like a fun thing to build.  Got some more lathe stuff coming from Ebay...thinking about doing something similar.

That is part of a vintage countershaft....got to go to EBay:)

[clockboy]

Interesting debate my take is the there is no real need for a toothed belt with a watchmakers lathe because of the small cuts made. My worry would be if there was a mishap/jam the smooth belt would slip but a toothed belt would till try to carry on turning the lathe. 

[watchweasol]

I would agree if it was using a toothed pulley then yes,  but some toothed belts are "V" belts toothed for easier curvature around pulleys but the "V"pulley is smooth so slippage occurs.  There was some Large printers I worked on that had both types driving the print barrel,  solid brass with a beryillium coating so the hammers did not flatten the characters..    600 Lpm and 300Lpm.  

[JohnR725]

 

5 hours ago, clockboy said:

My worry would be if there was a mishap/jam the smooth belt would slip but a toothed belt would till try to carry on turning the lathe. 

My only experience with watchmakers lathe belts before the sewing machine belt was round and smooth. I don't recall ever having a problem with round and smooth because there's always tension on the belt. Yes if you're trying to make a really aggressive cut it will probably slip but watchmakers lathes aren't really meant to be machining heavy cuts. Then there's the shape of the pulley on the lathe they seem to be designed for a round.

The link below shows lathe belting material and it's all round. Farther down the page some of its textured.

https://www.cousinsuk.com/product/lathe-belting-also-for-rota-barrel-drums?code=L58234

[Michael1962]

If you have round section pulleys, you should use round belt material. If you have V section pulleys, you should use a v-belt.

It should be remembered though that a v-belt only contacts the pulley on its sides. The inner face of the belt should not be running on the bottom surface of the V on the pulleys.

[Klassiker]

Well, the convention on watchmaking lathes is to use a round belt in a v-groove, hence my original question to LittleWatchShop.

[jdm]

12 minutes ago, Klassiker said:

Well, the convention on watchmaking lathes is to use a round belt in a v-groove, hence my original question to LittleWatchShop.

Correct. The material used is soft and will adapt itself to the shape of the pulley grove, and elastic enough to deal with some elongation. That is, self adjusting for tension. 

Very different from bigger belt machines. 

[LittleWatchShop]

I picked up another lathe...just because I guess.  I did not have a motor nor tail stock.  I scavenged a motor from an old sewing machine I had in the queue for the dump (whew, glad I woke up regarding that).

I needed a belt.  Imagine that.  After trying a leather shoe lace I did some research and found that some people use PU (polyurethane) belts and melt them together to form a continuous loop.

I do not have any PU, however, I have 3mm TPU (Thermoplastic Polyurethane) used for 3D printing.  Voila!  Seems to be working just fine.