Lathe Motor suggestion.

[Plato]

I recently bought my first lathe  - only a cheap one (in second hand lathe money), just to get me started.

However, as I've never even been near a watchmaker's lathe before I was a bit unsure of how to get it running properly. I didn't want to post too many novice questions so I thought I'd just crack on with buying a sewing machine motor and hope for the best - I could always ask for help if I got stuck with something later!!

The pictures below show what I think is a fairly decent set up, for a beginner...

It's not perfect as the belt is too small for the motor and too big for the lathe, I'm working on a solution - probably a bigger v-pulley for the lathe. The black v-pulley in the background of the first picture shows what I used first, it ran okay but it was being torn by the lathe pulley. Also, the power cables could be better placed but they're a bit short for where I wanted to run them.

The motor is a brushless synchronous motor which with the aid of the controller (which I stuck under the bench) can run from 200 to 5000 (I think) rpm in either direction. This should save me from having to use different sized pulleys for different speeds at the lathe. The speed is adjusted between an upper and lower limit via the lever on the side (last picture) - I removed the original spring which was set up for use with a mechanical foot lever, now it just stays in whatever position I leave it.

I'm ready to start learning how to use the lathe but thought I should post my progress here first. PLEASE let me know if anyone can see something wrong with this set up as I don't want to damage the lathe or myself.

[jdrichard]

  On 8/21/2021 at 3:07 PM, Plato said:

I recently bought my first lathe  - only a cheap one (in second hand lathe money), just to get me started.

However, as I've never even been near a watchmaker's lathe before I was a bit unsure of how to get it running properly. I didn't want to post too many novice questions so I thought I'd just crack on with buying a sewing machine motor and hope for the best - I could always ask for help if I got stuck with something later!!

The pictures below show what I think is a fairly decent set up, for a beginner...

It's not perfect as the belt is too small for the motor and too big for the lathe, I'm working on a solution - probably a bigger v-pulley for the lathe. The black v-pulley in the background of the first picture shows what I used first, it ran okay but it was being torn by the lathe pulley. Also, the power cables could be better placed but they're a bit short for where I wanted to run them.

The motor is a brushless synchronous motor which with the aid of the controller (which I stuck under the bench) can run from 200 to 5000 (I think) rpm in either direction. This should save me from having to use different sized pulleys for different speeds at the lathe. The speed is adjusted between an upper and lower limit via the lever on the side (last picture) - I removed the original spring which was set up for use with a mechanical foot lever, now it just stays in whatever position I leave it.

I'm ready to start learning how to use the lathe but thought I should post my progress here first. PLEASE let me know if anyone can see something wrong with this set up as I don't want to damage the lathe or myself.

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Check out my many lathe videos. Here is one.

 

[jdrichard]

Also this video for making a nice noiseless belt.

 

[Jon]

I agree with JD about the counter shaft, as this makes a big difference to keeping the torque whilst running at low speeds.

The countershaft will also get around the problem of the belt sizing, as pointed out by JD. I use the sewing machine motor belt to drive the countershaft and a rubber belt to drive from the countershaft to the lathe pulley. Job done!

I use the same set up and the counter shaft can be bought for about £100 to £150 which may seem a lot, but is well worth it, especially when running with a variable speed controller. One piece of advice I will give is, always keep the lathe and countershaft well lubricated, as it's easy to forget about it when you are concentrating using the lathe. I've caught myself doing it before and you don't want to run a lathe dry!

[Plato]

  On 8/21/2021 at 3:33 PM, Jon said:

I agree with JD about the counter shaft, as this makes a big difference to keeping the torque whilst running at low speeds.

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It's quite a powerful motor - 550W, so about 0.75hp - I was hoping that would overcome the issue?

  On 8/21/2021 at 3:33 PM, Jon said:

I use the same set up and the counter shaft can be bought for about £100 to £150 which may seem a lot, but is well worth it, especially when running with a variable speed controller.

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It's more a case of having the space, I'm at the limit of what I can fit in already... but, if need be then I'll have to find room!

  On 8/21/2021 at 3:33 PM, Jon said:

One piece of advice I will give is, always keep the lathe and countershaft well lubricated

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I definitely bore that in mind, Archie B. Perkins recommends clock oil so I used that before running it with the motor. I read 3 in 1 is okay too?

Thanks for your advice, I'm going to study things thoroughly before I start.

[oldhippy]

I had a sewing machine motor with a foot control on my watchmakers lathe. Not such a big motor as the one you are showing. It worked fine. You don't need hypa speed for watchmaking. Looks a nice set up.  

[Jon]

The power of the motor has nothing to do with the torque at low speeds, hence the countershaft.

You can have a really powerful motor, but when the speed is low, so will the torque 

I use 'airline oil' which is an ISO 22 oil, it's the same as hydraulic oil and is as cheap as chips https://www.toolstation.com/airline-oil/p27629.

It's also great when using on lathe work to keep the graver from blunting

[Jon]

  On 8/21/2021 at 3:51 PM, Plato said:

It's quite a powerful motor - 550W, so about 0.75hp - I was hoping that would overcome the issue?

It's more a case of having the space, I'm at the limit of what I can fit in already... but, if need be then I'll have to find room!

I definitely bore that in mind, Archie B. Perkins recommends clock oil so I used that before running it with the motor. I read 3 in 1 is okay too?

Thanks for your advice, I'm going to study things thoroughly before I start.

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3 in 1 is too thin in my experience and opinion, but ask 10 watchmakers about oil and you'll get 15 different answers... lol

[Jon]

  On 8/21/2021 at 3:55 PM, oldhippy said:

I had a sewing machine motor with a foot control on my watchmakers lathe. Not such a big motor as the one you are showing. It worked fine. You don't need hypa speed for watchmaking. Looks a nice set up.  

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Same here, I like a foot control pedal

[Plato]

  On 8/21/2021 at 3:57 PM, Jon said:

You can have a really powerful motor, but when the speed is low, so will the torque 

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Does that apply to this motor? The older induction motors slowed down by reducing the applied voltage (I think), doesn't a synchronous motor just reduce the speed of the rotating magnetic field? The torque should stay the same. It's basically the same type of motor used in cars now. 

 

  On 8/21/2021 at 3:57 PM, Jon said:

I use 'airline oil' which is an ISO 22 oil, it's the same as hydraulic oil and is as cheap as chips https://www.toolstation.com/airline-oil/p27629.

It's also great when using on lathe work to keep the graver from blunting

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Definitely going to bear this in mind, I bought some Vallorbe gravers recommended by Dean DK (YouTube link is on the forum here somewhere) they look delicate. I'm going to start on brass first, roughly what speed for a 4mm rod? 

[jdm]

  On 8/21/2021 at 5:05 PM, Plato said:

Does that apply to this motor? The older induction motors slowed down by reducing the applied voltage (I think), doesn't a synchronous motor just reduce the speed of the rotating magnetic field? The torque should stay the same. It's basically the same type of motor used in cars now. 

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Jon is correct. With small motors, AC or DC, induction or permanent magnet, low speed means low torque. The only partial exception is with 3-phase motors used with a VFD inverter. But even a small 200W 3-phase is too big for a watchmakers lathe. In the end, stepped pulleys and countershafet were, and are the way to go.

[Plato]

  On 8/21/2021 at 7:01 PM, jdm said:

Jon is correct. With small motors, AC or DC, induction or permanent magnet, low speed means low torque. The only partial exception is with 3-phase motors used with a VFD inverter. But even a small 200W 3-phase is too big for a watchmakers lathe. In the end, stepped pulleys and countershafet were, and are the way to go.

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It's none of the motors you've mentioned. I'm pretty sure it's this one:

 

https://en.m.wikipedia.org/wiki/Brushless_DC_electric_motor

 

I wish I had a better background/understanding to explain. It's a synthesised 3-phase motor, all of the power is applied at any speed. Are you thinking of the ac/dc universal motor? The one I'm using is not the same technology, it's the one used in PC hard drives, Dyson vacuums, Tesla cars, deWalt drills, etc.

[jdm]

  On 8/21/2021 at 8:00 PM, Plato said:

The one I'm using is not the same technology, it's the one used in PC hard drives, Dyson vacuums, Tesla cars, deWalt drills, etc.

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Sorry I did not read well the initial post. Do you have a product link? I think on a watchmaker lathe there is really no (lack of) torque issue with either old or new technology motors, so this one might be a bit of overkill but if it works and is affordable that's all good.

The reason why I am fixated on torque at very low speeds, now going a bit off topic, is because when threading or even plain turning a 90mm dia work on a micro or mini lathe, brushed DC motor and PWM controller simply won't do. Even traditional 3-phase motor are going brushless, but at this time they cost 4x more. I am in this conundrum and was thinking to get a cheap low speed DC motor which is directly usable on my 250mm lathe, but at the time it lands and clears customs is not that cheap anymore. I see there are now brushless DC kits upgrades, then again quite expensive.

[Jon]

  On 8/21/2021 at 8:00 PM, Plato said:

It's none of the motors you've mentioned. I'm pretty sure it's this one:

 

https://en.m.wikipedia.org/wiki/Brushless_DC_electric_motor

 

I wish I had a better background/understanding to explain. It's a synthesised 3-phase motor, all of the power is applied at any speed. Are you thinking of the ac/dc universal motor? The one I'm using is not the same technology, it's the one used in PC hard drives, Dyson vacuums, Tesla cars, deWalt drills, etc.

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Could you post a link to what the motor is or where you bought it from. That would be handy

[Jon]

  On 8/21/2021 at 5:05 PM, Plato said:

Does that apply to this motor? The older induction motors slowed down by reducing the applied voltage (I think), doesn't a synchronous motor just reduce the speed of the rotating magnetic field? The torque should stay the same. It's basically the same type of motor used in cars now. 

 

Definitely going to bear this in mind, I bought some Vallorbe gravers recommended by Dean DK (YouTube link is on the forum here somewhere) they look delicate. I'm going to start on brass first, roughly what speed for a 4mm rod? 

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For 4 mm brass rod, try turning between 800 to 1200 rpm. It's more about the feel of it that will tell you how fast to go, as you may find it better to turn at a lower speed, which will cut just as well. Brass is more forgiving when using a graver.

[Plato]

  On 8/21/2021 at 8:50 PM, jdm said:

Sorry I did not read well the initial post. Do you have a product link? I think on a watchmaker lathe there is really no (lack of) torque issue with either old or new technologies motor, so this one might be a bit of overkill but if it works and is affordable that's all good.

The reason why I am fixated on torque at very low speeds, now going a bit off topic, is because when threading or even plain turning a 90mm dia work on a micro or mini lathe, brushed DC motor and PWM controller simply won't do. Even traditional 3-phase motor are going brushless, but a this time they cost 4x more. I am in this conundrum and was thinking get a cheap low speed DC motor which is directly usable on my 250mm lathe, but at the time it lands and clears customs is not that cheap anymore. I see there are now brushless DC kits upgrades, then again a lot more expensive.

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Google "JACK Low Energy Silent Servo Motor - Industrial Sewing Machine Motor - JK513A", I'm using my tablet so it's awkward to post a link. 

[Plato]

  On 8/21/2021 at 11:57 PM, Jon said:

For 4 mm brass rod, try turning between 800 to 1200 rpm.

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Cheers. 

[Plato]

I finally got round to using the lathe...

I set the motor to 1100 rpm max which should have given me approximately 1200 rpm max at the lathe. This is my first attempt, hopefully a passable square shoulder.

I've got nothing to compare the motor/lathe to but I haven't damaged the graver (yet)! I put a bit of oil on kitchen roll and cleaned the graver with it fairly often.