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DC Treadmill Motor

Power supply required

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Mervyn Karwot15/05/2019 15:05:33
9 forum posts

I have a DC motor from a PremierFit T100 treadmill which will be used to lift and lower the head of my FB2 mill drill. The numbers on the label are H2-25-4100 and there is no other information apart from a serial number. I cannot find any details about the motor on PremierFit brochures on the internet. Can anyone tell me the power supply I require to run this motor? Many thanks.

AdrianR16/05/2019 08:57:07
272 forum posts
20 photos

I am not saying it is this, but...

If you google for H2-25-4100 you find "WG17082104 H2-25-4100"

Google for WG17082104 and you find "CARL LEWIS TREADMILL MODEL - MOT566 *** MNF; 2007/01 MOTOR P.M.D.C. POWER 1.75HP VOLTAGE 180VDC MAX SPEED 4400RPM"

The images of the PremierFit motor show quite thin wires, look to be about 1.5mm sq. which suggests high voltage low current.

John Haine16/05/2019 10:10:30
2694 forum posts
138 photos

1.75 HP x 746 = 1.3 kW. 1300/180 = 7.25 amps. That's a chunky controller but fairly standard. Search ebay for controllers. For your intended application you aren't going to need anything like its full power (I hope!) so you could get away with perhaps a 500 W controller. At this power rating the motor probably has a would field so make sure the controller will support that. (I see that on the photo it has 3 wires so probably have a common connection.)

Ian Parkin16/05/2019 10:25:53
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665 forum posts
174 photos

If this is to replace the manual handle for lifting the head of your mill that motor wont work you need a geared motor that has an output of perhaps 60 rpm.

look for one of these on ebay a parvalux geared motor 12 or 24v

dsc00854 (large).jpg

You only then need a low amps ( 3 or so ) power supply and a simple dpdt switch

Edited By Ian Parkin on 16/05/2019 10:26:28

duncan webster16/05/2019 10:27:23
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2271 forum posts
33 photos

If John is correct and it's wound field with 3 wire connection you'll need to do some surgery to find the other end of the field winding, otherwise you won't be able to reverse it. 1.3kW is very much overkill by the way

mgnbuk16/05/2019 10:27:46
533 forum posts
23 photos

At this power rating the motor probably has a would field

Motor part no includes "MOTOR P.M.D.C. POWER 1.75HP "

PMDC = Permanent magnet DC ? The small wound field DC motors I have come across have had the field as a separate enity, not connected to the armature. Frame size looks rather compact to have a wound field as well + no apparent cooling slots - wound fields tend to run warm & require ventilating.

Nigel B

SillyOldDuffer16/05/2019 10:47:33
4856 forum posts
1021 photos

Posted by mgnbuk on 16/05/2019 10:27:46:

...

PMDC = Permanent magnet DC ? ...

Nigel B

I thought 'Pulse Modulated DC', but Nigel's suggestion is much better! Three wires to a permanent magnet motor suggests one of them is for a thermal sensor.  I don't know if treadmill motors are reversible?

Dave

Edited By SillyOldDuffer on 16/05/2019 10:49:01

AdrianR16/05/2019 11:45:20
272 forum posts
20 photos

The picture I saw wires were red, black and green/yellow which I would assume are plus, minus and earth

Adrian

Mervyn Karwot16/05/2019 12:08:22
9 forum posts

Thanks everyone for your information. I cannot post a photo on the forum as the "insert image" cannot find an album on my computer. The motor as AdrianR says has red black and earth wires and I have tested it with a 12v DC model railway controller. It goes forward and backwards OK but without any great power.

I was wondering if H2 was 2Horse Power and 25 was 25amp

Then

2 x 746watts = 1492watts

and 1492watts divided by 25amp = 60volts DC

Mervyn

Ian S C16/05/2019 12:32:19
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7447 forum posts
230 photos

The tread mill motor that I had was 1,2 hp at 200v DC, permanent magnet. To reverse just swap the + -. It worked well as a generator, but now back in motor service driving a water pump from a generator driven by a single cylinder stationary engine(demo at shows).

Ian S C

mgnbuk16/05/2019 19:39:36
533 forum posts
23 photos

I have tested it with a 12v DC model railway controller. It goes forward and backwards OK but without any great power.

Fixed field DC motors are constant torque devices, so power reduces as rpm reduces. Rpm is dependant on the voltage applied & the torque comes from the current - so if the motor is 1.75hp @ 4400 rpm from its rated current at 180VDC as suggested, then at 12V you would get around 300rpm and around 0.12hp assuming you supplied the rated current (7.25ish amps).

1.3Kw (as suggested above) at 4400 rpm is around 2.8Nm torque - should be enough to move the head on an FB2, but you would be running the motor at a very low voltage to get the motor to run slowly enough (unless you require very rapid retractions !) . It doesn't strike me as being the ideal motor for the job - FWIW I have bought a 3Nm stepper motor to do the same job on my FB2 clone, but I particularly want to use mine to get a constant downwards cutting feedrate (I have it in mind to try boring motorcycle cylinders, so need to be able to feed at a constant rate for around 160mm) - powered elevation will be a bonus . I have all the bits, just need the "round tuit" now to get it mounted on the machine !

Nigel B

John Haine16/05/2019 21:47:24
2694 forum posts
138 photos

I took it as read that if used to drive a mill head the motor would need to be drastically geared down, not direct drive.

John Haine16/05/2019 21:47:46
2694 forum posts
138 photos

I took it as read that if used to drive a mill head the motor would need to be drastically geared down, not direct drive.

Mervyn Karwot17/05/2019 09:40:13
9 forum posts

Thanks once again for your information. I would prefer a direct drive motor rather than geared as I can still use the hand wheel manually. The pulley on the motor is smaller than on the hand wheel so the motor will turn several times for one turn of the hand wheel.

Thanks Nigel for your information. A stepper motor would be better but I am on a budget and I don't need such a fine motion as you do. I just want to be able to raise and lower the head without turning the hand wheel hundreds of times. I am trying to find out what voltage I require so that I don't waste money on a wrong power source.

Unfortunately, I cannot get a photo put up on this page as there seems to be a problem finding the album.

Mervyn

Ian Parkin17/05/2019 09:57:23
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665 forum posts
174 photos

I don’t want to rain on your project Mervyn but i will say that direct drive wont work without a reduction of perhaps 15 fold...just saying

John Haine17/05/2019 11:44:33
2694 forum posts
138 photos

I agree, I think that using a motor designed to deliver high power at high rotational speed is the wrong approach. Actually you don't need very much power at all. Suppose the mill head weighed 50 kilos, or approx 500 Newtons, and you wanted to lift it 1 metre in 100 seconds. The total energy is 500 joules, or 500 watt-seconds, or 5 watts power. Why use a 1.3 kW motor for that? Much better to use a little DC gear motor and a 12 or 24 V power supply with a PWM controller - lots of solutions have been described here. If you want to also use the handwheel then a simple dog clutch is easy to arrange. The web page in that link by Mike Cox describes an X axis power feed but the principle easily adapted to the Z axis.

Mervyn Karwot17/05/2019 12:30:42
9 forum posts

Thanks again for your ideas. I have now tested it and the head moves up and down.

The motor is actually 1 HP continuous and it moves the T100 treadmill from 1km/hr to 10km/hr on a 4% slope with a person weighing up to 90kgs It has a polybelt drive with a ratio similar to mine, about 1 to 4.

I connected it to a 12v leisure battery and with a pulse modulated controller and reverser, it can raise and lower the head. Now, as Nigel said the speed is dependent on the voltage and the torque on the current so I will look for a 60 volt DC or larger power unit.

I have read what you said that other motors are better but that is what I have and I am on a budget. If this doesn't work, I will be moving the head manually as I have done in the past.

Thanks to everyone, Mervyn

Ian S C17/05/2019 13:03:25
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7447 forum posts
230 photos

Mervyn, a better motor might be an old 12v windscreen wiper motor, I use an old Lucas one for the feed on the mill table, I have a 10 tooth sprocket on an extended shaft on the worm wheel, driving a 20 tooth sprocket on the mill lead screw. I run it of a 18v DC power supply and just use a rotary switch with resistors to control the speed. The drive is via a bit of bike chain that is loose enough to be lifted off to remove the power drive. Cheap, simple, and fairly ugly.

Ian S C

SillyOldDuffer17/05/2019 13:47:02
4856 forum posts
1021 photos

When selecting the power supply, a few sums might help. Assuming the motor normally runs at a treadmill typical 180V, then the equivalent resistance of the motor for 750W would be about 43ohms. I=V/R so:

  • 12V across 43 ohms would draw about 0.3A for about 4W out.
  • 24V across 43ohms would draw 0.6A for 14W,
  • 36V across 43ohms would draw 0.8A for 30W,
  • and 60V would draw 1.4A for 84W.

Note the power output is proportional to the square of the voltage; lots more oomph from 60V compared with 12V, let alone 180. Mervyn may be able to guess which power supply is needed from the rate of turn he got from his 12V leisure battery. A 24V 1A psu would be roughly 3 times as fast, and 36V 1A would be ten times faster. A 60V 2A supply would be 21 times faster than the leisure battery, which might be a bit hairy!

Maybe Mervyn has to be reported for cruelty to motors, but if it works, hurrah! Switching power supplies up to 48V are dirt cheap these days. I wouldn't recommend running the motor at full power with 4000rpm geared down to the drill handle. The power and torque might be enough to tear the head off a Fobco, probably not what's needed. Under volting the same big motor ungeared should be safer, perhaps even a good idea!

Dave

Ian P17/05/2019 15:08:46
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2254 forum posts
91 photos

Dave

Although Mervyn mentioned direct drive, he did also say 4:1 belt drive. so that changes your calculations slightly.

I agree with your remarks about the Cruelty to Motors Society, maybe its a registered charity these daysindecision

Ian P

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