Operating American lathes in Europe: 60 Hz or 50 Hz?

[jesusfwrl]

With directly driven lathes (Neumann) and gear driven lathes (Fairchild, Presto 8DG), your only realistic option is a good frequency converter.

With idler driven lathes, you could also use a frequency converter, but it might actually be cheaper to use a properly designed step-down transformer and exchange the rubber idlers with new ones, dimensioned to offer the correct ratio for the desired platter speed.

Read more on the Agnew Analog Blog, including lubrication recommendations, an overview of the centrifugal switches built into vintage motors, and of course, the source of all the parts you may need in your quest for the good old American sound in Europe.

https://agnewanalog.com/blog/2019/02/16/presto-lathe-motor/

IMG_6306.JPG

[symatic]

I changed the motors out entirely, and run a modern motor via an Invertek Optidrive E2, which allows me to control the speed. I hooked the motor up to the 45rpm half of my Presto's mechanism, as 33 resulted in the speed being way to slow becasue of how it's all geared for a 60hz motor.

I haven't got round to accurately measuring the speed. looks ok on the strobe but when i recently cut a test using some audio that loops at 133.333bpm, i could see the grooves were offset from each other, indicating the lathe isnt running perfectly on speed. I'll hopefully be able to calibrate it a little more accurately just using the Invertek, but as it's digital it might not hit that perfect sweet spot.... in which case I'll have to integrate some sort of additional gearing mechanism, or just bypass the presto's existing gear mech....

[rsimms3]

Again, as I noted on Facebook, idler size does not impact final speed of the platter for the lathe you featured. Please stop trying to sell services and show your math to support such a claim.

[rsimms3]

speed.jpg

Top shows a simple Presto idler setup as described in the article, bottom shows speed change through reduction ratio as seen in a Federal 16s lathe where you flip the idler over to become a pulley. And when it says size does/doesn't matter that is ONLY referencing the rubber intermediary of an idler system, a direct rim drive system (K8) is different.

[jesusfwrl]

Rsimms3, I do agree with you that "idlers" might not be the appropriate term to use for this, since by definition, idlers are not meant to be part of the transmission ratio. The very popular term "idler drive turntable" is also not technically accurate, since an idler does not provide the drive. In the case of two-step rubber rollers, where both steps are simultaneously engaged, one on the motor shaft/sleeve and one on the platter rim, these do form a step-down (or step-up) arrangement and are no longer really "idlers" but rollers. We could call this entire theme friction drive.

The rollers on the particular MRC-16 I featured are two-step rollers and as such, do affect the transmission ratio and the speed of rotation of the platter.
This is not a claim, but simply how this particular unit works.
It is not my fault, I did not design it, honestly!

But, I could sell you some high resolution pictures if the assembly, along with the math, scribbled on the back of an envelope... (just joking)!

See my Rek-O-Kut restoration thread for reference to the same roller style: https://www.lathetrolls.com/viewtopic.php?f=15&t=6913

I changed the motors out entirely, and run a modern motor via an Invertek Optidrive E2, which allows me to control the speed. I hooked the motor up to the 45rpm half of my Presto's mechanism, as 33 resulted in the speed being way to slow becasue of how it's all geared for a 60hz motor.[...].

Symatic, this is really interesting! What motor did you use?
How is it in terms of noise/vibration/rumble?
Do you still have the original motor?
What Presto model is it?
Any pictures you'd like to share?

[rsimms3]

Interesting, I may have found photographic evidence to support your claim which would throw an interesting monkey wrench in the general realm of knowledge on Presto transmission setups. The MRC16 would be an exception to the rule vs the standard. In order to test this, please provide the inner and outer diameter of the brass capstan seen in the picture of the lathe you are working with currently.

[buddybolden]

Hi, I have the 50hz diameters for european capstans, may post you, if you want

[symatic]

Symatic, this is really interesting! What motor did you use?
How is it in terms of noise/vibration/rumble?
Do you still have the original motor?
What Presto model is it?
Any pictures you'd like to share?

hi jesus

I have documented most of my lathe's story in the Presto 14B/Caruso Project thread, but specifically about the motors:

I asked a guy called Bleddyn at The Motor Contol Warehouse here in the UK (found them online) about what to do with the Bodine motors that came with the Presto. He explained it would be hard to convert the power on those accurately without risking damaging the old motors.
another option was building a new gear box but i didn't want to go there.

So he suggested this motor and the Invertek E2 drive to control it's speed. looks like a pump motor or something.

TECA, 3 phase, 63 frame motor, 4 pole, 11mm keyed shaft, 63mm from base to shaft centre, 0.18kW (1/4 HP), B3 foot mount
https://www.motorcontrolwarehouse.co.uk/teca-ie1-0-18kw-3-phase-motor.html

1 x Invertek Optidrive E3, single phase 240V in, 3 phase 240V out, IP66 (wall mount), 0.37kW
https://www.motorcontrolwarehouse.co.uk/invertek-ode-3-120023-1f1x-optidrive-e3.html

The Invertek is a Variable Frequency Drive, which allows me to slow the motor down, and I just set the speed by eye with a strobe disk on the platter.
Here it is in operation the other night:

https://www.youtube.com/watch?v=wMn5FPbfVdw&feature=youtu.be

as you can see the Teca Motor is mounted to the Presto mechanism using a custom made bracket - that was more expensive than the motor! but it needed to accomodate a longer motor, and also have space for the custom adapter we had made to get from the 1mm shaft of the Teca motor to the 9mm hole in the Presto Mechanism.

This motor is a bit more noisy than the original Bodine, but it seems ok regarding vibration.

The Presto gear mechanism has some suspension - the big wheel you see turning is actually 2 wheels on top of each other, attached by 3 rubber pieces that interleave between the 2 wheels, forming a kind of suspension/dampening system while still transferring the rotational force for the platter.

I'm more concerned with the rubmling of the bearings under the platter, i'll ask in another thread about that.

I also have been wondering about this as an option: getting a UK specced motor that runs at 1800 RPM - 1800 is what the Bodines were specced to at 60hz, they only ran at 1500 at 50hz which is why my speed was so off in the beginning.

If I ran a 1800 rmp 50hz motor, in theory it would all line up nicely again.... something like this:
https://www.omega.co.uk/pptst/OMAT_SERIES.html#description

[jesusfwrl]

Interesting, I may have found photographic evidence to support your claim which would throw an interesting monkey wrench in the general realm of knowledge on Presto transmission setups. The MRC16 would be an exception to the rule vs the standard. In order to test this, please provide the inner and outer diameter of the brass capstan seen in the picture of the lathe you are working with currently.

What, free of charge...?!?
Just joking.
I will next time I take off the platter. Currently working on the overhead.

Hi, I have the 50hz diameters for european capstans, may post you, if you want

If you feel like posting them, it might help someone.

hi jesus

I have documented most of my lathe's story in the Presto 14B/Caruso Project thread, but specifically about the motors:

I asked a guy called Bleddyn at The Motor Contol Warehouse here in the UK (found them online) about what to do with the Bodine motors that came with the Presto. He explained it would be hard to convert the power on those accurately without risking damaging the old motors.

It is not hard at all, just not super-cheap. The Agnew Analog Type 191 (https://agnewanalog.com/products/191.shtml) does exactly that, safely and reliably, on any synchronous AC motor.

another option was building a new gear box but i didn't want to go there.

This would be considerably more difficult, since it must be VERY quiet.

So he suggested this motor and the Invertek E2 drive to control it's speed. looks like a pump motor or something.

TECA, 3 phase, 63 frame motor, 4 pole, 11mm keyed shaft, 63mm from base to shaft centre, 0.18kW (1/4 HP), B3 foot mount
https://www.motorcontrolwarehouse.co.uk/teca-ie1-0-18kw-3-phase-motor.html

1 x Invertek Optidrive E3, single phase 240V in, 3 phase 240V out, IP66 (wall mount), 0.37kW
https://www.motorcontrolwarehouse.co.uk/invertek-ode-3-120023-1f1x-optidrive-e3.html

The Invertek is a Variable Frequency Drive, which allows me to slow the motor down,

I have an Invertek VFD here at the moment. Too noisy with most old motors, and makes them run hot. But probably good for modern motors, designed with VFD's in mind.

and I just set the speed by eye with a strobe disk on the platter.
Here it is in operation the other night:

https://www.youtube.com/watch?v=wMn5FPbfVdw&feature=youtu.be

as you can see the Teca Motor is mounted to the Presto mechanism using a custom made bracket - that was more expensive than the motor! but it needed to accomodate a longer motor, and also have space for the custom adapter we had made to get from the 1mm shaft of the Teca motor to the 9mm hole in the Presto Mechanism.

Looks interesting!

This motor is a bit more noisy than the original Bodine, but it seems ok regarding vibration.

Three phase motors are usually vibrating less. But the Bodine motors are very good in this respect.

The Presto gear mechanism has some suspension - the big wheel you see turning is actually 2 wheels on top of each other, attached by 3 rubber pieces that interleave between the 2 wheels, forming a kind of suspension/dampening system while still transferring the rotational force for the platter.

I'm more concerned with the rubmling of the bearings under the platter, i'll ask in another thread about that.

Hmmm.... There shouldn't be anything really noticeable there!

I also have been wondering about this as an option: getting a UK specced motor that runs at 1800 RPM - 1800 is what the Bodines were specced to at 60hz, they only ran at 1500 at 50hz which is why my speed was so off in the beginning.

If I ran a 1800 rmp 50hz motor, in theory it would all line up nicely again.... something like this:
https://www.omega.co.uk/pptst/OMAT_SERIES.html#description

Long story... But in short, Synchronous AC motors (https://agnewanalog.com/diskrecording/motors/synchronousac.shtml) can only spin at a specific speed, defined by frequency. They sort of " lock" to the frequency of the supply. If the supply frequency is stable (most inverters and cheap VFDs are not) then these motors are really stable and ideal to use in such a setup. The speed cannot be 1800 rpm at 50 Hz though. A 4-pole motor will spin at 1800 rpm only at 60 Hz, and reduce to 1500 rpm at 50 Hz.

Synchronous Motor RPM = 60 f/pole pairs
where f is the supply frequency, and pole pairs is the number of pole pairs in the particular motor.

Then there are induction motors (https://agnewanalog.com/diskrecording/motors/inductionac/index.shtml). These cannot spin at 1800 rpm at 60 Hz (or 1500 rpm at 50 Hz) because they have "slip", so their speed is always a bit lower than synchronous speed. Most general purpose industrial motors are of the induction type, not synchronous. They are not as stable in speed as slip varies with load. Three-phase induction motors do not vibrate too much, but any of them designed to work from a single phase supply do vibrate, a bit too much for my liking, even for industrial uses.

So, you ideally want a Synchronous AC motor. You already have one, the Bodine. You'd have to spend a lot to get a better motor nowadays. The only catch is that you can't operate it at 50 Hz on your machine. If you can afford it, the Type 191 is the best option for this machine, at GBP 600.

As an exercise in engineering problem solving, there is one more option: A counter-shaft!
Instead of a motor, just mount a shaft, running on two bearings, with a pulley in the middle. Mount the Bodine on a heavy base, isolated from the machine, on the floor, with a pulley on its shaft. Run it at 50 Hz, 1500 rpm. Make the pulley dimensions such that you would have a step-up ratio of 1.2, so the countershaft would spin at 1800 rpm when belt-driven by the motor. I can design and machine this setup for anyone interested. It would reduce rumble further, but would also reduce transmission efficiency (the latter mostly being an academic consideration).

[symatic]

thanks for your thorough answer, Jesus!

all in all it osunds like maybe i have the best of a bad bunch of options then I sold the Bodines on to another troll who would benefit more than me, so I tihnk i'll focus on isolating my motor more and also getitng new bearings or servicing the existing bearings to reduce platter rumble

[rsimms3]

Or just buy your Bodine motor back, run it at 50hz with a new motor pulley with a larger diameter to account for the slower speed based on the different frequency. Changing the motor or frequency conversion is a complicated solution to a simple math/mechanical issue.

https://www.lathetrolls.com/viewtopic.php?f=1&t=8085&p=51898&hilit=50hz+capstan#p51890

[symatic]

I think there must be a reason for the big gearing system on the 14B though... could it be as simple as running the whole thing off a pulley rather than a geared motor?

[rsimms3]

Apologies, doesn't the 14b use direct drive to the platter? One motor on each side? If that's the case, what I describe doesn't apply.

[symatic]

14b used 2 bodine motors originally, one for 45 one for 33, these were attached to a gear mechanism, just like the 8D i think.

you can see mine in operation in this video, with the new motor in place of the old bodine.

https://www.youtube.com/watch?v=wMn5FPbfVdw&feature=youtu.be

I'm thinking that in order to run a Bodine motor at 50hz, with the pully system described earlier, I would have to bypass the gear system all together. not impossible, but seems like i'm reinventing the wheel maybe.