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New aftermarket motor db200 lathe

 

My old cast iron unimat has some strange motor (220v) on it which is very noisy.?
I want to replace it with something else, I see a lot of folks moved to the dc option with transformers and speed control. I would prefer to stay with 220v ac. I was looking at sowing machine motors with a foot control, any suggestios or ideas would be much appreciated.

Dave
Borneo
 

On Sat, Apr 13, 2024 at 06:13 AM, David James wrote:
My old cast iron unimat has some strange motor (220v) on it which is very noisy.?
I want to replace it with something else, I see a lot of folks moved to the dc option with transformers and speed control. I would prefer to stay with 220v ac. I was looking at sowing machine motors with a foot control, any suggestios or ideas would be much appreciated.
Sewing machine motors are generally not very quiet either. I have such a howler on my Pillar Tool, which I built according to the drawings by G.H.Thomas. The foot switch is a disaster. I have not yet understood how it works. So when you buy it, make sure which foot switch is included. The mechanical switches are no good. But a motor with approx. 150 -180 watts should be enough. When buying, you also have to pay attention to the direction of rotation, which is left and right. The motor should always run clockwise when looking at the shaft end.

Greetings
Bruno
 

Dave, there are very great differences between an AC series connected motor and the DC motors and their controllers that must be understood before you make a choice.
The orginal selection of an AC series connected ?motor was made for several reasons (largely cost I suspect). An AC series motor has a very good (high) top speed but a terrible load regulation. In that it is very forgiving of "chuck crashes" and a such not a bad selection for a what could be considered a beginners lathe which is small enough that it is easy to get fingers mixed up in the works.
A DC motor and a proper "chopper" speed controller are the exact opposite in that what ever speed is selected the motor will try and maintain what ever the load upto the current limit of the controller. Thats very good for quality finishes and large amounts of metal removal ( compared to the AC motor anyway). And of course being able to set the speed perfectly for required cut ( and not have to keep changing belt settings). The controller reference "pot" can always be hooked up to foot pedal if required.?
For me changing to a DC drive was a "no brainer" I went to a much larger motor but only used a fixed toothed belt drive with only one high speed ratio. The result was a very wide chuck speed range without having to keep changing pulley ratios, but still acceptable maximum torque (plus a minature DC breaker to control chuck crashes).

Please excuse the "condition" of the lathe other dusty operations are ongoing.

Bob
 






On Friday, April 12, 2024, 11:13 PM, David James via groups.io <davebjames@...> wrote:

My old cast iron unimat has some strange motor (220v) on it which is very noisy.?
I want to replace it with something else, I see a lot of folks moved to the dc option with transformers and speed control. I would prefer to stay with 220v ac. I was looking at sowing machine motors with a foot control, any suggestios or ideas would be much appreciated.

Dave
Borneo

Dave,
I am one who has converted to DC and it works well. I know it means purchasing DC equipment but it is worth it in the long run. For one it is extremely quiet compared to an AC motor. I do not regret making the change.

Dick
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--
http://www.homemadetools.net/forum/?OFF-SET-tailstock-center-65965#post105972
?SMALL TURRET TOOL POST PLANS?
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?QUICK CHANGE LATHE TURRET
?MINI LATHE COMPOUND PIVOT MODIFICATION
 

¿ªÔÆÌåÓý

Hi Bob,

I¡¯m curious.

Do you find the tooth belt still lets the lathe create a smooth finish or does the engagement of the teeth result in harmonics on the surface.? There¡¯s so little mass compared to a larger lathe running with toothed belts for drive.?

Maybe it¡¯s not an issue but usually a toothed belt drive is noisier than the O-Ring drive.

John

?

?

From: [email protected] [mailto:[email protected]] On Behalf Of Bob T
Sent: April 13, 2024 3:12 AM
To: David James; [email protected]
Subject: Re: [Unimat] New aftermarket motor db200 lathe

?

Dave, there are very great differences between an AC series connected motor and the DC motors and their controllers that must be understood before you make a choice.
The orginal selection of an AC series connected ?motor was made for several reasons (largely cost I suspect). An AC series motor has a very good (high) top speed but a terrible load regulation. In that it is very forgiving of "chuck crashes" and a such not a bad selection for a what could be considered a beginners lathe which is small enough that it is easy to get fingers mixed up in the works.
A DC motor and a proper "chopper" speed controller are the exact opposite in that what ever speed is selected the motor will try and maintain what ever the load upto the current limit of the controller. Thats very good for quality finishes and large amounts of metal removal ( compared to the AC motor anyway). And of course being able to set the speed perfectly for required cut ( and not have to keep changing belt settings). The controller reference "pot" can always be hooked up to foot pedal if required.?
For me changing to a DC drive was a "no brainer" I went to a much larger motor but only used a fixed toothed belt drive with only one high speed ratio. The result was a very wide chuck speed range without having to keep changing pulley ratios, but still acceptable maximum torque (plus a minature DC breaker to control chuck crashes).

Please excuse the "condition" of the lathe other dusty operations are ongoing.

Bob

 

John, thats interesting..... When I put on the toothed belt drive mechanical noise was far from my mind. I had just seen the "blurb" on the "new" unimat 4 which came ( as I remember ) with a tooth belt drive. I decided that was the way to go. Being an electical engineer I designed and made a controller for it (A linear one ! ) complete with a small dc motor on the back of the main motor to act as "tacho feedback" . I think I remember checking the smoothness of current drawn and didn't see any ripple in it. Certainly I have never noticed any mechanical effects on the surface of of the work piece. The motor shown is not the original that I used in the conversion. The original was a flat pancake servo motor from a large line printer. That motor was very smooth indeed....doing 0 to 10,000 rpm in about 1 second ! (the controller had a several second ramp built in for comfort).
Bob
 

¿ªÔÆÌåÓý

Thanks for that detailed reply.

John

?

?

From: Bob T [mailto:zs6bxi@...]
Sent: April 13, 2024 4:35 PM
To: John Dammeyer; [email protected]
Subject: Re: [Unimat] New aftermarket motor db200 lathe

?

John, thats interesting..... When I put on the toothed belt drive mechanical noise was far from my mind. I had just seen the "blurb" on the "new" unimat 4 which came ( as I remember ) with a tooth belt drive. I decided that was the way to go. Being an electical engineer I designed and made a controller for it (A linear one ! ) complete with a small dc motor on the back of the main motor to act as "tacho feedback" . I think I remember checking the smoothness of current drawn and didn't see any ripple in it. Certainly I have never noticed any mechanical effects on the surface of of the work piece. The motor shown is not the original that I used in the conversion. The original was a flat pancake servo motor from a large line printer. That motor was very smooth indeed....doing 0 to 10,000 rpm in about 1 second ! (the controller had a several second ramp built in for comfort).
Bob

 

All,?

Thanks for the info regarding the motor, I was not aware the AC motors were so noisy so it looks like I will need to go for the DC scooter motor. I have such a small space to work I will have to try to mount the transformer and speed control somewhere else to avoid cluttering up my work space.

Regards

Dave
Borneo Island
 

Dave,
I had the opposite happen with my motor change I got a 24V DC and made a controller box but had a lot of noise from it, a friend gave me a 220V AC motor off a small lathe I made up a controller and found it far better, I powered the same pulleys on the SL/DB so I could get really low speed when needed with lots of torque and I am more than happy in how it all works.
If you had been closer I would have offered you the DC setup to try on yours.

Phill?
 

This is the setup I used. The motor is extremely quiet, and while the mounting lugs are slightly wider than the stock motor mounting holes, I only had to slot one of them by a couple millimeters or so to get a good fit.

Hilitand 24V DC Motor 150W High Speed CW/CCW Permanent Magnet DC Motor for DIY Generator (5500RPM(24V))

RioRand 7-70V PWM DC Motor Speed Controller Switch 30A

Mxfans 40x30x8MM Silver Aluminum 2-Step Groove Fixed Bore Pulley with Wrench for Motor Shaft


I already had a 24v power supply, but you can pick one up for fairly cheap. Frankly with that speed controller you can have the power supply and controller board mounted in an enclosure and tucked away under your bench and then have a small enclosure for the speed control potentiometer mounted by the lathe and just run the power cable from the controller to the motor and the 3 wire cable from the potentiometer to the controller. Or just mount the whole controller to the lathe since it really isn't very big, and then just run the power cable from the power supply up to the controller.

The pulley I used is OK, it actually works pretty well, but I may make a new one or bore out the old one since the motor shaft is larger than the stock motor.

Paul


On Sun, Apr 14, 2024, 1:32?AM phill005 via <phill05=[email protected]> wrote:
Dave,
I had the opposite happen with my motor change I got a 24V DC and made a controller box but had a lot of noise from it, a friend gave me a 220V AC motor off a small lathe I made up a controller and found it far better, I powered the same pulleys on the SL/DB so I could get really low speed when needed with lots of torque and I am more than happy in how it all works.
If you had been closer I would have offered you the DC setup to try on yours.

Phill?

 

Paul,

Thank you, it looks like its the way I must go.

Regards

Dave
Borneo Island

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