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24v dc motor powering a drill press

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Steve King 521/03/2019 21:42:55
55 forum posts
76 photos

I have this old drill press and it's great but as with a lot of drill presses it's just too fast for drilling metal.


I am hoping to attach this 24v dc motor to power it. It's from a mobility scooter .


I'll need a 240v a.c. input, 24v dc out put transformer and some sort of 24v dc input 0-24v dc output controller (I think)

Can any one point me in the right direction?

I think this is the correct place for this post but if not, admin please move it.



Ian P21/03/2019 21:58:04
2179 forum posts
90 photos

A PSU to drive that motor will be a serious and expensive bit of kit!

Transformers themselves give an AC output, to rectify and control (presumably) the speed of the motor the cost will mount up. Since that motor will be running at 2 or 3 times the speed of most induction motors (1450 or 2800rpm) you will need to make changes to the drive arrangements.

Not sure why you think most pillar drills are too fast for drilling metal IMHO many are too slow.


John Haine21/03/2019 22:17:47
2610 forum posts
133 photos

Likewise, surprised you think the drill is too fast.

John Haine21/03/2019 22:21:34
2610 forum posts
133 photos

Puzzled. Plate says 24v 11 amps. 24x11=264watts, not 950! Something doesn't compute.

Emgee21/03/2019 22:26:34
1191 forum posts
207 photos

Steve, controller here will run the motor, you will also need a transformer and rectifier unit to provide the 24v 15A DC supply.



Mike Poole21/03/2019 22:44:58
2117 forum posts
51 photos

If your drill has a slow speed of 480rpm then you should be ok drilling steel up to about 17mm and a top speed of 4220 then you are ok down to 2mm.


duncan webster22/03/2019 00:23:22
2234 forum posts
32 photos
Posted by John Haine on 21/03/2019 22:21:34:

Puzzled. Plate says 24v 11 amps. 24x11=264watts, not 950! Something doesn't compute.

perhaps it's 110A, and motor is inefficient, 2640W in, 950 out. Must say I agree putting a 5400 rpm motor on instead of 1500 (probably) doesn't make sense

Edited By duncan webster on 22/03/2019 00:46:40

Martin W22/03/2019 01:24:40
792 forum posts
29 photos


There is no need for a transformer as you can buy switched mode power supplies here. They have 24V DC units with output currents that will easily meet the 11A input current for under £30, a 24V 20A DC smps is listed at £28-99p postage included. All that is then required is a speed controller that can handle 20A or so and the jobs done. No need to try and build your own and spend a fortune on large transformers, bridge rectifiers, capacitors and a suitable case to hold it all. Just 2 relatively small units that can be mounted in a smallish enclosure.



A suitable speed controller can be found here

Edited By Martin W on 22/03/2019 01:29:19

Paul Lousick22/03/2019 02:22:32
1168 forum posts
496 photos

Also be aware that the torque of the motor is reduced if you lower the speed and if it has an integral cooling fan the air flow will also be reduced and can result in overheating when fully loaded at slow speed.


Ed Dinning 122/03/2019 05:55:39
24 forum posts

Hi Steve, if you can get the electronic controller that went with this motor, many of your problems will be solved as it will give variable speed with a current limiting characteristic, so speed should not drop with load.

You will then need a fairly hefty mains to 24v DCpower supply unit.

Cheers, Ed

Steve King 522/03/2019 07:04:55
55 forum posts
76 photos

Thanks for all your input guys, much appreciated.

Robert Atkinson 222/03/2019 07:38:09
367 forum posts
21 photos

It's a 4 brush motor with a flat braided strap for connection, despite the spacing on the nameplate, that alone says it's 110A current rating not 11A. You can get speed controllers designed for robots that will handle this sort of current. Search for high current pwm motor speed control e.g. **LINK** (from search no idea if it's any good).
Unless doing sustained drilling a couple of 12V lead acid batteries and a intelligent charger would be easier than a 100A power supply.
Brushed DC motors do not loose torque with reduced speed. Torque is only limited by the available supply current and voltage, current rating of motor / supply and mechanical strength. Normally the winding resistance will limit the current and thus torque, but if you increase the voltage to compensate the torque will go up. A controller with speed feedback will do this automatically. Obviously the available mechanical power goes down if you reduce the speed at the same torque, this is the laws of physics.

Robert G8RPI.

3404622/03/2019 08:03:20
744 forum posts
8 photos

My Unimat 3 has the 12v DC motor with the variable speed controller

I was told the electrical control is basically a 240 V ac dimmer switch feeding a bridge rectifier.

It is a standard off the shelf unit at around £20 from ebay


Barrie Lever22/03/2019 08:23:05
323 forum posts
1 photos

How sure are we that the motor is 110A? That connector does not look like something that you would see on a continuosly rated device that is capable of drawing 110A? look at the size of the input plug/cable to tell that 110A will fry that in short order.

Up to a point forget the nameplate it is riddled with errors but don't forget your basic elecrical knowledge and practical experience.

Small mobility scooters are less than 500W and even the biggest types are less than 1.5Kw.


mechman4822/03/2019 10:12:16
2461 forum posts
371 photos


How about changing rpm mechanically... change pulley sizes... a quick search on Google brought up a quick ref. could work out a cheaper method...


mechman4822/03/2019 10:15:54
2461 forum posts
371 photos

How about changing rpm mechanically... change pulley sizes... a quick search on Google brought up a quick ref. could work out a cheaper method...



mechman4822/03/2019 10:36:19
2461 forum posts
371 photos

… Also this as an aid , the top formula

pulley calculator.jpg

Ref. My Newnes Mechanical engineers pocket book.


SillyOldDuffer22/03/2019 11:21:52
4723 forum posts
1010 photos

Before worrying about that contradictory motor plate and drill speeds I advise testing the motor by connecting it to a car battery! With the photo the right way up, it looks as is someone has written 'MOTOR U/S' on it, where U/S likely means "unserviceable", ie broken.


I was able to find the PA05-A130-SY54B motor listed as a spare part in a scooter manual. It confirms 5400rpm and 950W, also that the controller is rated to 160A. The scooter is powered by two 12V batteries making 24V likely.

I guess either:

  • 950W out is the maximum peak output (ie 24V at 40A), and 24V at 11A = 264W is the continuous rating. OR
  • the plate means 110A, and it's the other way round, ie 950W continuous, 2640W peak.

Drill speed rule of thumb, 10000rpm /drill diameter. Thus 1mm diameter drill about 10000rpm, 10mm drill about 1000rpm, 20mm drill 500rpm. etc. Roughly!


Clive India22/03/2019 12:27:55
187 forum posts

11A at 24v = 264W.

and this thing produces 950W output.

Where can I get one of these motors which surely defies the laws of physics and generates its own energy?

Where is the hidden nucleur reactor?

Bazyle22/03/2019 14:05:09
4729 forum posts
186 photos

If the motor is labelled U/S it is probable an overload (heavy user plus kerb) or overheating (long run uphill) either burnt out the windings or the commutator.
I'm kind of surprised some people don't seem to understand DC motors to the extent of how they can take huge extra current and provide huge extra torque at low speed to cope with starting or sudden load but of course not sustain it.
It is also why battery drills can perform so well but when the battery dies you can't realistically use them with a bench psu and get the same performance.

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