Low power/Continous duty electric motors

[RainbowsParticipant @rainbows]

Does anyone know where to get motors of 90-120w that can be used continously? I see a lot of little lathes (think Adept size) run by sewing machine motors but these usually run at silly speeds and if you use them too long they get hotter than is probably good for them. Ones on ebay in the local area tend to be 1HP or more and pieces and would fling the lathe through a wall as soon as something jammed.

I was wondering about snatching the motor out of a washing machine but even that might be too powerful.

[RainbowsParticipant @rainbows]

[Keith LongParticipant @keithlong89920]

Plenty of standard induction motors down to about 1/4 HP (180w) about (new), below that you possibly looking at shaded pole motors and I'm not at all sure what the torque curve for those looks like, and whether they'd be suitable for a lathe. You probably need to talk to a motor supplier to see what they can offer. A 1/4 HP would be fine on a small lathe, if you're worried about getting a jam up just let the belt run loose enough to slip or include a coupling somewhere with a weak shear pin.

[AjohnwParticipant @ajohnw51620]

The power you need depends one what speed you are going to run the lathe at. On some lathes that increase the speed to say 5,000rpm I hp wouldn't be that unusual, 1/2 hp more like the norm even up to 10,000 rpm on small lathes such as a Pultra.

You don't say where you are but there are a couple of multi listings on ebay in the uk. One goes down to 120w the other 180w ( 1/4 hp ). Failing that you should be able to get what you want from a motor supplier. If it's capacitor run in my experience they tend to run rather hot what ever the load. Capacitor start and run helps with that but I used a capacitor run once for some time and other than initial worry it didn't cause any problems at all. They can have problems spinning up heavy loads but in practice I would say that's unlikely on very small lathes.

It's worth mentioning that belts slip so tighten them until they will take the size of cut etc that you need and then a bit more.

John

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[john fletcher 1Participant @johnfletcher1]

For a motor, contact members of your local Model engineering group/society, usually some one has motor for sale or knows of some one who has. Modern washing machine motor run far to fast and are very noisy and have no protection against bit entering the windings. Shaded pole are no good either. Get your self from some where or other a split phase or capacitor start 1425 rpm motor. Lathe motors start off load so starting torque doesn't really matter. Motor do get warm and modern ones get HOT to touch,its when you get that burnt varnish smell you start to worry, even all's not lost. When capacitor start and run motors are up to speed and the centrifugal switch opens they then behaves or run in a similar manner to a the straight capacitor start motor.Ted

[Boiler BriParticipant @boilerbri]

Try searching 'oriental motor company' in the UK they do reasonable Panasonic copies. All low wattage and continuos rating.

http://www.oriental-motor.co.uk/

Brian

[AjohnwParticipant @ajohnw51620]

The whole idea of the switched capacitor start motors John is to provide sufficient torque to get all of the parts on a lathe spinning and up to speed. Then that capacitor is switched out. It's not unusual in a number of areas to find that the torque needed to do that in a reasonable time or even at all is more than the actual running torque.

One of my favourite places to look is ebay new other. All sorts crop up. There appears to be some pure capacitor run motors on there at the moment but going on the one I used they don't arf get hot what ever load is on it.

John

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[Ian S CParticipant @iansc]

A lot of modern motors where ever they are made get quite hot on a long run, the modern insulation is designed to run at a higher temperature than that of 40/50 years ago.

Rainbows does not actually say what he wants to use the motor for, although he mentions Adept lathes and sewing machine motors. I have a Super Adept, and a 90W sewing machine motor was not up to the job, it now has a 180 W 1450rpm shaded pole motor, this just about does it, but does not have the torque of a .25hp split phase motor. In NZ it is possible to still get good old ex washing machine split phase 1/4hp or 1/3hp 1450rpm motors, I have one running an old wall mounted black smiths drill press.

Ian S C

[Clive FosterParticipant @clivefoster55965]

Pure capacitor run motors, those with a permanently connected capacitor and winding not the common capacitor start ones with centrifugal switch, are compact relative to power output and can frequently be found quite inexpensively. These should be avoided as they are not suitable for varying loads and get very hot if left to free run or used when lightly loaded. Which generally occurs a lot on machine tool duties.

This sort of motor is intended for fan and similar applications low torque demand at start up is coupled to high demand at rated power with a rapid rise as speed increases towards and above rated speed. They are a pseudo two phase design where the interaction between the main winding, capacitor winding and capacitor comes into balance to produce a very efficient machine a rated speed and load. Unfortunately the sweet spot is quite narrow and outside it the motor becomes very inefficient with large, unproductive, currents circulating making it very hot indeed. Running off load they typically become far too hot to touch after a minute or so and meltdown in five to ten. However when correctly matched to the right type of load and running for long periods of time they last for ages. Not only are they very efficient but also a the cheapest and most durable, typically close to 3 phase in lifetime, type of single phase motor outside the mouse power region so they are often found in scrap machinery.

Pity we can rarely use them. I wrecked tow nice ones before finding a book expelling the design!

Clive

[Bill MullParticipant @billmull]

I have used motors from http://www.minimotor.com

And http://www.parvalux.com

Both were bought through RS components.

The mini motor ones were 150w 3 phase operated from a single to 3 phase mitsubishi or danfoss inverter variable speed drive.Happily running up to 16 hours a day .

Edited By Liam Mulcahy on 13/09/2015 14:19:10

[Ian S CParticipant @iansc]

I have one 150W 1450 rpm shaded pole capacitor run motor driving the line shaft in a model of a workshop, I had the workshop at a show a couple of years ago, and left the motor running, after 1/2 an hour or so a lot of the magic white smoke found it's way out of the capacitor, and things came to a stop. A new capacitor, and it's up and going again, but not a continuous run motor, maybe 10/15 min.

Ian S C

[Nick_GParticipant @nick_g]

Posted by Rainbows on 12/09/2015 14:15:00:

Does anyone know where to get motors of 90-120w that can be used continously?

.

An extractor fan motor.?

A lot of those are asked to run 24 / 7

Nick

[Ian S CParticipant @iansc]

Nick, those motors run well less than their maximum power rating, and have a great cooling system, the load is the system, the main thing to go wrong with them is muck in the bearings, then the bearings running dry, they are usually Oilite bushes.

Ian S C

[RainbowsParticipant @rainbows]

Posted by Ian S C on 13/09/2015 09:27:59:

A lot of modern motors where ever they are made get quite hot on a long run, the modern insulation is designed to run at a higher temperature than that of 40/50 years ago.

Rainbows does not actually say what he wants to use the motor for, although he mentions Adept lathes and sewing machine motors. I have a Super Adept, and a 90W sewing machine motor was not up to the job, it now has a 180 W 1450rpm shaded pole motor, this just about does it, but does not have the torque of a .25hp split phase motor. In NZ it is possible to still get good old ex washing machine split phase 1/4hp or 1/3hp 1450rpm motors, I have one running an old wall mounted black smiths drill press.

Ian S C

My current need is indeed for a small lathe. When I had a Adept I used a 90w sewing machine motor too and while it just about worked I wasn't happy with it either. Wasn't sure if under powered or just a bad motor design for the job. I don't think I have ever seen a shaded pole motor over 10 watts though.

If 1/4 hp motors aren't too big I will keep a look out for one of those though. I have seen them around on ebay.

[bodgeParticipant @bodge]

On the small lathe i have , similar size to your myford M l 1 ish as im guessing this is the machine you going to hang it on… I used the motor off one of those small hobby drilling machines. See machine mart ,item-Clarke cdp 5rb [ they were much cheaper a few years back , B&Q at one time were selling them £ 29.99 , which was tenner cheaper than the one i"d bought a few months before, so i bought a second , i figured that was an acceptable price for a motor ,couple pulleys ,pair of bearing ,and a drive belt an a few other odd bits ] These are capacitor run motors ,and yes as other folk have already said they Do run a bit HOT ! And i did wonder if that was going to be an issue ! So i thought i would really give it some , as in if its going fail ,best fail now. So i ran it dusk till dawn = a good 10 hours ,didnt even turn it off when i stopped for tea break [ it was a fair sized job , 6 inch dia by 9 inch long—the job was wood former for a small furnace barrel — also it was driving through the back gear ,and running power feed….it didnt fail!! it seems that when this type of motor fails its usually the the capacitor that fails …[ possibly cos one side of the cap is in contact with or very close to the hot motor casing, easily fixed ! Anyway point is machine mart have a spares department maybe the motor is available as a spare, might be worth giving them a try ,or maybe similar is available on ebay ? These motors seem to come 2 sizes 250 & 350 watt not much in it size wise the 250s a bit smaller, it was 250 i used, also the motor starts with the load off ,the way i rigged the drive, thought id at least give it a bit of a chance . bodge.

ps I know thats a long time to turn a wood former , But i really was trying to get motor to fail !

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