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Alternative motor for the Unimat SL

 

Good evening,
?
This is my first post to the site so apologies if I ramble a little.

First of all, many thanks to all involved in sorting out the recent situation.
?
I am a retired combustion engineer from the steel industry and have developed an interest in the repair of grandfather clock movements.
?
Very quickly it became apparent that some form of lathe was required for this and after much internet searching, during which I found this site, went for the EMCO Unimat SL due to it's compact size.
?
After repairing, repainting and general repairs the original motor was refitted but I found it too noisy and time restrained.
?
The lathe also came with an old 90w sewing machine motor controlled via a foot pedal.
I tried this but it proved problematic due to not being able to control my left foot and the old motor was not powerful enough to achieve higher speeds under load.
?
After research I bought a 230v 550w DC servo motor from Amazon, designed for an industrial sewing machine.
?
It was simplicity itself to fit and is more than adequate for my needs. Very quiet, up to 4500 rpm and reversible at the touch of a button.
?
It comes with sufficient brackets to fit most needs. I inverted the original motor bracket and mounted it through the idler pulley bearing hole. This gives the ability to adjust belt tension as well.?
?
It has a very efficient electrical braking system, sensible as it is designed for a sewing machine and an operator would not want it to run on if they were in difficulty.
?
It will stop, with a thump, from 4500 rpm to zero in the blink of an eye.
?
Unfortunately for a Unimat SL this leaves more than enough momentum in the chuck for it to screw itself off and end up anywhere in the workshop, at speed.
?
This motor braking is simple to turn off in the parameters of the controller, but by default it is set to maximum.
?
The normally foot pedal activated on/off and speed control switch was fitted in an appropriate place for hand operation and the return spring removed.
This switch increases the motor speed in steps from 0 to 100% of the desired speed set in the main motor controller. It does this with a Hall effect sensor with a magnet.
?
There is a hole in the top of the switch and this means it does occasionally get swarf on it and in it. This would eventually cause electrical problems.
?
As part of a normal lathe clean down I inspect and remove any debris to avoid this.
?
Some photographs of the setup have been included for your perusal.
?
I am very happy to provide any information you may require.
?
kindest regards,

David

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Hello David:

I'm interested in the extended bed rods on the headstock end.? Why did you configure the lathe this way?

-Guy-

On November 8, 2021 at 11:21 AM "David via groups.io" <andreadee@...> wrote:

Good evening,
?
This is my first post to the site so apologies if I ramble a little.

First of all, many thanks to all involved in sorting out the recent situation.
?
I am a retired combustion engineer from the steel industry and have developed an interest in the repair of grandfather clock movements.
?
Very quickly it became apparent that some form of lathe was required for this and after much internet searching, during which I found this site, went for the EMCO Unimat SL due to it's compact size.
?
After repairing, repainting and general repairs the original motor was refitted but I found it too noisy and time restrained.
?
The lathe also came with an old 90w sewing machine motor controlled via a foot pedal.
I tried this but it proved problematic due to not being able to control my left foot and the old motor was not powerful enough to achieve higher speeds under load.
?
After research I bought a 230v 550w DC servo motor from Amazon, designed for an industrial sewing machine.
?
It was simplicity itself to fit and is more than adequate for my needs. Very quiet, up to 4500 rpm and reversible at the touch of a button.
?
It comes with sufficient brackets to fit most needs. I inverted the original motor bracket and mounted it through the idler pulley bearing hole. This gives the ability to adjust belt tension as well.?
?
It has a very efficient electrical braking system, sensible as it is designed for a sewing machine and an operator would not want it to run on if they were in difficulty.
?
It will stop, with a thump, from 4500 rpm to zero in the blink of an eye.
?
Unfortunately for a Unimat SL this leaves more than enough momentum in the chuck for it to screw itself off and end up anywhere in the workshop, at speed.
?
This motor braking is simple to turn off in the parameters of the controller, but by default it is set to maximum.
?
The normally foot pedal activated on/off and speed control switch was fitted in an appropriate place for hand operation and the return spring removed.
This switch increases the motor speed in steps from 0 to 100% of the desired speed set in the main motor controller. It does this with a Hall effect sensor with a magnet.
?
There is a hole in the top of the switch and this means it does occasionally get swarf on it and in it. This would eventually cause electrical problems.
?
As part of a normal lathe clean down I inspect and remove any debris to avoid this.
?
Some photographs of the setup have been included for your perusal.
?
I am very happy to provide any information you may require.
?
kindest regards,

David


?
 

That's a roughly 3/4HP motor, which I think a bit much for the Unimat. My South Bend Heavy 10L shipped from the factory with a 3/4HP motor. It's about a thousand pounds of toolroom lathe. I suspect that launching the chuck would be rather traumatic even if it isn't as big as the ones SB uses. :) I'm not sure the ways to prevent that on a SB lathe like mine would work on an SL, but fitting a smaller motor might make it less likely.?

Looks like a well thought-out layout, and I suppose it if does what you want it to do, and you know not to stop it like that, is should work fine for you. Currently, my smallest lathe is a Harbor Freight 93212 7x10 mini-lathe, about a hundred pounds worth of lathe. I am trying to work a? deal to get a Unimat SL myself. I know that techniques that work on small lathes will work on a larger one, where the reverse is not necessarily true. Though with that motor, you can probably use carbide tooling, I'm thinking the lathe itself is pretty small, and light weight. That might be a problem with continued use.?

I'd be interested in more of your experience, so please keep posting!

Bill in OKC
 

¿ªÔÆÌåÓý

David,

?

Very nice looking, but with that much power on such a small lathe you are leaving yourself open to bending or tearing apart the headstock or the support rods.? It is kind of like those guys who put an excessively large engine in an otherwise stock car and end up ripping off the driveshaft or differential because of the excessive torque developed by the engine.? You may want to consider fastening the drive pulley with a soft shear pin (usually soft aluminum) that will give way before ruining the spindle should jam.?

?

Best wishes,

?

Jerry F.?

?

From: [email protected] [mailto:[email protected]] On Behalf Of David via groups.io
Sent: Monday, November 08, 2021 8:21 AM
To: [email protected]
Subject: [Unimat] Alternative motor for the Unimat SL

?

Good evening,

?

This is my first post to the site so apologies if I ramble a little.

First of all, many thanks to all involved in sorting out the recent situation.

?

I am a retired combustion engineer from the steel industry and have developed an interest in the repair of grandfather clock movements.

?

Very quickly it became apparent that some form of lathe was required for this and after much internet searching, during which I found this site, went for the EMCO Unimat SL due to it's compact size.

?

After repairing, repainting and general repairs the original motor was refitted but I found it too noisy and time restrained.

?

The lathe also came with an old 90w sewing machine motor controlled via a foot pedal.

I tried this but it proved problematic due to not being able to control my left foot and the old motor was not powerful enough to achieve higher speeds under load.

?

After research I bought a 230v 550w DC servo motor from Amazon, designed for an industrial sewing machine.

?

It was simplicity itself to fit and is more than adequate for my needs Very quiet, up to 4500 rpm and reversible at the touch of a button.

?

It comes with sufficient brackets to fit most needs. I inverted the original motor bracket and mounted it through the idler pulley bearing hole. This gives the ability to adjust belt tension as well.?

?

It has a very efficient electrical braking system, sensible as it is designed for a sewing machine and an operator would not want it to run on if they were in difficulty.

?

It will stop, with a thump, from 4500 rpm to zero in the blink of an eye.

?

Unfortunately for a Unimat SL this leaves more than enough momentum in the chuck for it to screw itself off and end up anywhere in the workshop, at speed.

?

This motor braking is simple to turn off in the parameters of the controller, but by default it is set to maximum.

?

The normally foot pedal activated on/off and speed control switch was fitted in an appropriate place for hand operation and the return spring removed.

This switch increases the motor speed in steps from 0 to 100% of the desired speed set in the main motor controller. It does this with a Hall effect sensor with a magnet.

?

There is a hole in the top of the switch and this means it does occasionally get swarf on it and in it. This would eventually cause electrical problems.

?

As part of a normal lathe clean down I inspect and remove any debris to avoid this.

?

Some photographs of the setup have been included for your perusal.

?

I am very happy to provide any information you may require.

?

kindest regards,

David

?

Scanned by and confirmed virus-free.

?
 

Oh dear, I'm about to get my self into trouble again. I too run a similar setup on my unimat with a "large" DC motor doing the driving. I run a toothed wheel drive system with only one fixed ratio (about 2.5 :1 reduction). The motor is ~ 400 watts and I have installed a small DC circuit breaker in the line to the motor (6 amp). so if I do "crash" then the results are not too bad. The thing to remember about this sort of setup is that when one dispenses with the multiple pulley ratio's you need a much larger motor to get the correct torque at low speeds. The big benefit is that a quick twist of the speed reference pot and you have any speed that you can desire with out having to stop and change belts or worry about stalling. Its perfect for handling "large" diameter turning where you need to vary the chuck speed continuously as the cutting bit gets closer to the centre.

And yes I know its dirty. But thats honest dirt ( actually a hard wood dust) from making a wooden bush. Note the home made tool holder and home made copy of the indexing attachment.?

Bob
 

A common upgrade was a 24 volt scooter motor, used for powered wheelchairs. These can be speed controlled down to zero, and provide good power continuously. The power supply is inexpensive, and can run from 110 to 240 volts.

Neil
 

I agree with Neil.? The 135 - 150 watt scooter motor works well.? It can be drilled and tapped to match the screw spacing of the original Unimat motor.? The overall weight of the motor is reasonable.?


On Mon, Nov 8, 2021 at 10:43 PM Neil Morrison <neilsmorr@...> wrote:
A common upgrade was a 24 volt scooter motor, used for powered wheelchairs. These can be speed controlled down to zero, and provide good power continuously. The power supply is inexpensive, and can run from 110 to 240 volts.

Neil
 

Good morning Guy,

Thanks for taking the time to read my post.
When I acquired the lathe it was in a terrible state and the bed bars required immediate replacement.
As I think at some point in the future I may want the option of longer bars I only purchased one new set. I had to get them from Spain.
It was a bit of a fool's errand really.
If they are extended beyond the tailstock the long travel handle can't be fitted, if they go the headstock way then a standard pulley will not fit.
Anyway, applying the engineers ethos of adapt and overcome I already had a damaged headstock pulley that came with the lathe so I removed the outer beltway from it and it fits fine.

kindest regards,

David
 

Good morning,
I had several reasons for purchasing this motor.
It was a one click, four day delivery from Amazon, cost ?92 Stirling and is ready to use straight out of the box with no additional parts or work required. It even has an electrical plug fitted.
It weighs less than 4 pounds, the original motor weighs 3.5 pounds. This allows it to be fitted to the original bracket so the lathe can still be set up for milling.
It's very quiet and will run all day, useful in the confined space of my "workshop" ( loft/roof space of house ).
It runs on domestic single phase 230vac.

As to excessive power I have retained a single 6mm belt which I intentionally leave loose. This slips the second things get too much, not that it happens too often.
I am very aware that this is a small lathe I use for making and repairing clock parts, I only use it on brass and free cutting steels.

kindest regards,

David
 

Hello David
Your extended way bars are interesting to me. Do they serve a purpose? Or did you just use what rod stock you had on hand at the time for expediency?
Dick
[email protected]
 

Zitat von "OldToolmaker via groups.io" <old_toolmaker@...>:

> Hello David
> Your extended way bars are interesting to me. Do they serve a
> purpose? Or did you just use what rod stock you had on hand at the
> time for expediency?
> Dick


The Unimat DB/ SL adjustable T-bar Tool Rest, extended waybars, wood turning spur drive center and three very small chisels = Unimat Woodturning Set
Lui
 

Lui,
Thank you for the explanation. Was this kit an ¡°after market¡± kit or an original Unimat marketed kit?
Dick
[email protected]
 

Zitat von "OldToolmaker via groups.io" <old_toolmaker@...>:

Emco original.. long time ago..
Lui


> Lui,
> Thank you for the explanation. Was this kit an ?after market? kit or
> an original Unimat marketed kit?
> Dick
>
>
>
>
>
>
 

Good evening,

Many apologies for not giving the actual motor details in my previous post.

On Amazon, search for HUSUPER 550w Sewing Machine Servo Motor. ?91.89 Stirling as of an hour ago.

kindest regards,

David
 

This is the type of motor most of us bought:?

?
Neil
-----
 

Actually the way bars are supposed to extend from the tailstock end.
They were part of the wood turning kit and were meant to extend the working length of the bed by allowing you to install the tailstock outside the end of the lathe bed.
They are part # DB230-1.
 

There was a guy on the web who sold Unimat parts, he had the long extensions and a stub? tail section that came with them. I bought one from him a few years ago. I can not remember who he was. Great site with lots of parts.
?Jeff


-----Original Message-----
From: Richard Burrows <bluerandonee@...>
To: David <andreadee@...>; [email protected]
Sent: Tue, Nov 9, 2021 8:27 pm
Subject: Re: [Unimat] Alternative motor for the Unimat SL

Actually the way bars are supposed to extend from the tailstock end.
They were part of the wood turning kit and were meant to extend the working length of the bed by allowing you to install the tailstock outside the end of the lathe bed.
They are part # DB230-1.
Richard Swanson
 

Perhaps it was??
Tom's toolstore...at? tomstoolstore.com

?(413) 237-6827 tomstoolstore@...


I've bought a few items from him?

R. Barry Swanson


On Tuesday, November 9, 2021, 08:21:49 PM MST, Jkle379184 via groups.io <jkle379184@...> wrote:


There was a guy on the web who sold Unimat parts, he had the long extensions and a stub? tail section that came with them. I bought one from him a few years ago. I can not remember who he was. Great site with lots of parts.
?Jeff


-----Original Message-----
From: Richard Burrows <bluerandonee@...>
To: David <andreadee@...>; [email protected]
Sent: Tue, Nov 9, 2021 8:27 pm
Subject: Re: [Unimat] Alternative motor for the Unimat SL

Actually the way bars are supposed to extend from the tailstock end.
They were part of the wood turning kit and were meant to extend the working length of the bed by allowing you to install the tailstock outside the end of the lathe bed.
They are part # DB230-1.
 

Hi Richard,
Your name sounds familiar to me. Did you ever work in the plastic molding industry?
If so, we may have crossed paths somewhere in the past.
Dick
 

For the extended bed, Tom's Tool Store does or at least used to have cut ends of Unimat beds....He sold the headstock end for mounting the milling column mid bed giving better x axis motion for milling and drilling.? The tailstock end was to extend the bed particularly for wood turning.? I had an idea of cutting two beds? remove the head from one and the tail from the other? way bars to be precision 12mm shafting? instead of drill rod so as to increase bed length allowing CNC ops without giving up distance between centers for pen turning.


Ed Samsen

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