How hot does the motor on your mill/lathe run?

[IRTParticipant @irt]

I have just purchased a Warco GH18 mill.

Running it up for the first time, the spindle turns freely, and there are no nasty noises. I can see the fan on the motor is turning.

Running the lowest gear ratio under no load, the motor temperature is up to nearly 100deg C after about 10 minutes.

I will phone Warco in the week to confirm, but can I assume the motor is continuously rated and this temperature is normal?

Thanks.

[IRTParticipant @irt]

Warco GH18 mill motor temperature.

[Neil WyattModerator @neilwyatt]

A modern motor shoudl be able to run too hot for your hand to be kept on it, but that seems excessive for no load.

It may need running in or perhaps the centrifugal start switch (if fitted) isn't opening?

Neil

[not done it yetParticipant @notdoneityet]

Is the fan turning at motor speed? There should be quite an airflow generated around the motor casing.

What is the actual temperature and how much current/power is it actually using? If the case is at 100 degrees Celsius, the windings will be considerably hotter. I would be checking the details on the motor rating plate. All relevant detail should be on that. Meanings for the different symbols are documented on the internet.

This might be a useful read: https://www.machinedesign.com/technologies/hot-topic-motor-temperature

Edited By not done it yet on 25/08/2019 02:15:23

[michael howarth 1Participant @michaelhowarth1]

My Warco WM14 mill/drill ran very hot from the time I first bought it, about 8 years ago. I fitted a computer cooling fan in the housing which keeps things within bounds and touch wood……..

Mick

[ChrisBParticipant @chrisb35596]

Seems to be a common thing with these type of machines. My WM18 does the same, although I never checked the motor temperature, the quill will get warm enough in a matter of minutes. It never got hot enough you can't touch it tho…I guess the motor will be hotter than the quill tho.

Have a look here **LINK** there's a link in that thread which further discusses the temperature issues.

Chris

[JasonBModerator @jasonb]

This is not a variable speed machine with the motor tucked away in the head, its a big flange mount motor on the top here

[I.M. OUTAHEREParticipant @i-m-outahere]

I would take the belts off the motor and see if it runs cooler , 100c seems too hot for my liking – somewhere between 30- 60 deg would seem more normal to me . Cold = happy for induction motors .

[IRTParticipant @irt]

I ran it for 20 minutes this morning, and it only reached 85 degrees.

Maybe it does only need a bit of running in?

The spindle is cool, and I can't find a rating plate on the motor.

I will keep an eye on the temperature and run it each gear/ each direction and see if things improve.

Thanks.

[Clive FosterParticipant @clivefoster55965]

Its not uncommon for motors to run rather hot off load. Something to do with self generated internal circulating currents I believe. Allegedly designing things that way wins a bit more oomph and better torque curve at operating speeds when its operating as it should with the internally generated voltage balancing against the supply.

Most extreme examples are the "pseudo two phase" fixed capacitor single phase motors made for fan duties. Extremely efficient when running a fan at design load but if run off load for any length of time they will literally cook themselves to death. Took me ten minutes to prove that when I wrecked a rather nice new surplus, super cheap, bargain from Bull Electronics in Croydon maybe 35 – 40 years ago. At, as I recall it, £2 (ish) for a 1/2 HP motor there had to be a catch!

Clive

[Brian GParticipant @briang]

Posted by XD 351 on 25/08/2019 08:32:59:

I would take the belts off the motor and see if it runs cooler , 100c seems too hot for my liking – somewhere between 30- 60 deg would seem more normal to me . Cold = happy for induction motors .

Might be worth measuring the ambient temperature as well as the motor temperature. It is nearly 30c outside in Southern England right now, so it could be 40+ in a shed or garage, which will of course increase the motor temperature.

Brian

[John RutzenParticipant @johnrutzen76569]

I have an Amadeal mill which I am very pleased with. The brushless DC motor never even runs warm never mind hot. Even with prolonged use it's still cold. There must be something wrong with yours. My 3 phase motor on my lathe which is converted using capacitors to run on single phase never runs hot either. Warm at the most.

[SillyOldDufferModerator @sillyoldduffer]

I'm against beginner's looking for problems in new machines because inexperience can lead one up the garden path. Very easy to end up chasing 'problems' that don't exist, or don't matter in practice. Don't ask how I know! The problem is high-accuracy measurement isn't easy, and in this case the temperature characteristic of an off-load motor is unknown. There may be an analogy with blank firing guns getting hotter than guns firing live ammunition. The reason is that propelling a lump of lead down range cools the gases by doing work. Similarly, a car engine left idling on a hot day will soon start the electric fan.

I think it's better to put machines to work as a way of detecting problems. Only when something is wrong start testing to determine the cause. Fully equipped experts are the exception, it's guessing that's to be avoided.

Worth talking to Warco in case this turns into a Warranty Claim, but I'd want to confirm there's a real problem by making the mill cut metal in a normal work-cycle. Does the motor overheat when used normally?

Dave

[not done it yetParticipant @notdoneityet]

I was perusing some bandsaw specs recently. Most appeared to have quite high-powered motors compared to a few which seemed decidedly underpowered, but on one machine spec the input and output specifications for the motor was included. The motor efficiency was almost unbelievably poor, IMO.

Ended my comparisons on motor power as some of those adverts were likely to be very misleading and the ‘lower powered’ machines were likely nearly as powerful as those highly ‘specced’ ones.

This example might be a similar scenario? I only want to know the output for comparison – the input will always be more, but I suppose that for a hobby machine the run factors are generally low, so efficiency may not be so important?.

[SamsarandaParticipant @samsaranda]

I have a Champion v20 mill from Chester, when carrying out some very slow drilling I was concerned that the motor was working very hard and getting very hot, I removed the motor shroud and directed a powerful fan on to the motor to keep it cool, worked fine and brought the motor temp down to acceptable level. Once that job was finished I obtained two 40 mm diameter computer cooling fans which I located in the front of the motor shroud and they pull plenty of cooling air across the motor so no more overheating.

Dave W

[Dave HalfordParticipant @davehalford22513]

Posted by not done it yet on 26/08/2019 10:00:48:

I was perusing some bandsaw specs recently. Most appeared to have quite high-powered motors compared to a few which seemed decidedly underpowered, but on one machine spec the input and output specifications for the motor was included. The motor efficiency was almost unbelievably poor, IMO.

Ended my comparisons on motor power as some of those adverts were likely to be very misleading and the ‘lower powered’ machines were likely nearly as powerful as those highly ‘specced’ ones.

This example might be a similar scenario? I only want to know the output for comparison – the input will always be more, but I suppose that for a hobby machine the run factors are generally low, so efficiency may not be so important?.

There are regs covering AC motor efficiency of 1hp (80%+) and above that should cover motors in machines, one doubts that these are followed by some far east imports given the CE mark fiasco.

[not done it yetParticipant @notdoneityet]

Posted by Dave Halford on 26/08/2019 11:31:53:

…..

There are regs covering AC motor efficiency of 1hp (80%+) and above that should cover motors in machines, one doubts that these are followed by some far east imports given the CE mark fiasco.

Dave, the ‘apparent’ power, at first glance, was well over 750W – but the power output was very much considerably below that value. Suppliers/marketing/manufacturers taking the something out of prospective purchasers by quoting misleading specifications….

I looked again for that advertising carp, earlier this morning, but could not locate the particular item which caught my attention. I had thought, previously, that it was an EU manufacturer but cannot be sure of this…

[larry phelan 1Participant @larryphelan1]

Not sure about mill motors, but the motor on my cheapy bandsaw does run quite hot. I thought this was not quite right until I read the good book, whigh said that this was normal and nothing to worry about, but I still dont like putting my hand on it. It,s a Chineese motor but has never given any trouble.

Now, the motor on my Lux mill, 1*5 hp never seems to get hot even after long runs, neither does the motor on my Craftsman lathe, so could there be an issue with tight bearings ?

[Les Jones 1Participant @lesjones1]

On the assumption that it is a single phase motor one possibility is that the centrifugal switch is not opening when the motor is up to speed. Before doing anything to the machine wait to see what Warco say about about the motor temperature.

Les.

[not done it yetParticipant @notdoneityet]

I found the advert .

It was on Stakesy’s website, but perhaps not of european manufacture.

**LINK**

850W input but only 445W output. Some considerable difference, that! Only a little over 50%

Now, if the Warco motor is of similar ilk, I do wonder what the real truth is, regarding the power of the machine.

If the output is a real 900W (which I would expect of a Warco product) then the heat loss could be as much as 225W at only 80% efficiency. But note Dave’s comment about far east imports so could be worse – but hope it’s not.

If on the other hand… on the same efficiency as the example above, the real power could be 900*445/850 = 470W with a heat dissipation of 430W!. That would be some heat to dissipate to the motor casing and to the forced air cooling.

Those figures would/should not apply for a motor running at low power. But who knows!

Edited to add that those input/output figures might include some mechanical losses, I suppose, but doubt it.

Edited By not done it yet on 26/08/2019 18:51:47

[IRTParticipant @irt]

I spoke to Warco today, and they confirmed that the motors do indeed run hot.

[john fletcher 1Participant @johnfletcher1]

Most modern motors run very hot when compared to older one when natural resin based insulation was used. Out of interest and I'm sure some one will correct the following if I've got it wrong. We used the following to assess the internal temperature of the winding of a motor after a run.. Example, measure the winding resistance before the test run, note ambient temperature as well. Run the motor say for an hour, then measure resistance again. If original Res was 20 ohms, and new 26. Divide the second Res by the first = 1.6, subtract 1 from 1.6 = .6, now divide .6 by .004, that is the temperature change, which should be added to the first temperature. I have one of those laser gun type of temperature measuring jobs, which I find very handy for about £6/7, from ebay. John

[Dave HalfordParticipant @davehalford22513]

Posted by Ian Thomson 2 on 27/08/2019 12:50:31:

I spoke to Warco today, and they confirmed that the motors do indeed run hot.

As all this is very hard to test at home just make sure you use the machine, don't leave it idle all winter burning the guarantee.

[not done it yetParticipant @notdoneityet]

To be honest, I would not expect any other response from Warco. They are supplying a low cost item, so it’s not going to have a high quality motor – it will be one that is just adequate.

If there is anything in the advertising hype (or even the operating manual) that indicates this machine is only for limited use (hobby, not commercial), don’t expect to get much change from them if the motor fails after six hours of hard labour in one stint!

Me? I would be checking the input power, after the running-in period. Easy enough to do with modern plug-in power meters these days. If, as Dave says, efficiency must be better than 80% for motors over one horse power (output) it is easy enough to check out the possible longevity (or not) of the drive. I hate wasting energy for no good reason.

[Martin Hamilton 1Participant @martinhamilton1]

As long as their isn't a problem with the motor which would obviously need sorting, i find running a small fan onto motors brings temps down quite a bit. On my Sherline lathe being a typical small low powered high revving motor will after a while start to run warm, in this very warm weather we have at the moment temps can climb quicker. I purchased one of the small 4w desk fans for £5 & run it all the time, i can run my Sherline for long periods now even in hot weather & the motor barely gets warm as the fan is running & blowing cool air onto the motor even when the lathe is stopped for measurement taking or tool changing etc.

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