Induction motor overheating fast

[Dennis Aspö]

So I got this 600W 1-phase motor I picked out of a tile saw (looks like a little table saw), I was hoping to use it for a disk sander but the motor gets real hot real fast and I am unsure if it's suitable. I am also unsure if it's really rated for 600W, it has no plate, the 600W is only on the casing for the tile saw itself. I wonder if taking it out of it's case could really have that much effect on it's ability to cool itself? It looks like a pretty standard motor for these things, except this one is 230V/50hz then. I am wondering if it's wort sticking a bunch of old CPU heat sinks on it or something like that to improve cooling, maybe enlarge the fan somehow, it's one of those neutral fans that works in either direction, perhaps one that sucked air in one direction would be better.

The application to which I want to put this motor (disk sander) surely shouldn't be much more strenuous than what it was designed for I think.

[Mike Schuch]

Sounds like a lot of work for a questionable motor. There are motors on my local craigslist pretty frequently in the $50 range that should be much better suited. I would look for a motor in the 1-2hp range for a disc sander.

Those little tile saws with 6" blades have a very small contact area with the tile. I think a disk sander would require considerably more hp to keep from stalling the motor if you plan to do anything more demanding than resharpening your toothpicks. :D

You can get a 12" disc sander from harbor freight for a little over $100 if you wait for a sale and use a 20% off coupon.

[Dennis Aspö]

I can't swing 50 bucks (two kids, mortage, one parent is about to go unemployed), margins are pretty much 0, it's free or nothing for me.

600W is still nearly 2/3rds of an HP I figured that would be plenty, checking with a power meter too and adding the disc didn't even change the amp draw (draws something like 1.7amps with just the shaft).


Also not american so I can't get anything like that. I'd rather build my own anyway, I like shop made tools.

[John McClanahan]

If you start it up and let it run with no load (not using it), does it still get hot fast? If so, there may be a problem in the motor. If not, then the sanding disk needs more power than the motor can deliver.


John

[Mike Henderson]

If you start it up and let it run with no load (not using it), does it still get hot fast? If so, there may be a problem in the motor. If not, then the sanding disk needs more power than the motor can deliver.


John
I agree with John. But let me ask a question: Is this an induction motor or a universal motor. If it's an induction motor and the motor gets excessively hot when it's running free you probably have a short between a couple of wires in the field coil. That's not easily fixable, or cheap to fix. I'd dump the motor.

If that's the problem and you put heat sinks on the motor, the motor will still eventually fail. The failure will involve a lot of smoke as the insulation on the field coil burns away.

Universal motors tend to get pretty hot under load so putting heat sinks on one would probably work okay. Under no load a Universal motor would run pretty cool.

Mike

[Oops, I see that in your title you said "Induction motor".]

[Mike Schuch]

I can't swing 50 bucks (two kids, mortage, one parent is about to go unemployed), margins are pretty much 0, it's free or nothing for me.

600W is still nearly 2/3rds of an HP I figured that would be plenty, checking with a power meter too and adding the disc didn't even change the amp draw (draws something like 1.7amps with just the shaft).


Also not american so I can't get anything like that. I'd rather build my own anyway, I like shop made tools.

Understandable, I like to craft tools myself. Like the others have stated a motor that heats up with no load just doesn't sound very promising to me.

Do you have a table saw or a radial arm saw? I picked up a 10" disc that mounted on my Radial Arm Saw made to be a disc sander. It worked well until my father gave me his Belt/Disc sander. I have seen similar discs for table saws. Of course the downside of saw mounted disc sanders is they are not as convenient because you are always swapping between the sanding disc and saw blades.

I use a disc sander a fair amount and I know that it takes a considerable amount of power to hog off a bunch of wood to shape a piece of stock. In my experience I don't think 2/3 hp will be very productive for anything but very small pieces. Do you have a particular project in mind or are you just thinking a disc sander would be handy to have? I use my disc sander occasionally for wood but I use it a lot for metal working.

[Dave Cullen]

Open the motor up and clean it out of dust and debris. Lubricate the bearings if they aren't sealed. Look for burnt windings. And make sure that your line voltage is close to what the motor needs.

Under load, an induction motor can reach 80°C, but with no load you should be easily able to hold your hand on it.

[Dennis Aspö]

Thanks for the tips, I'll have a look at the motor later and perhaps I'll measure its temperature during no load and see what I get and if it's inside proper operating range.

Going away on medical business with the kids across the country so no chance to look at it anymore for a week at least.

I have a table saw I could mount it in, it can take 12" blades so it's a possibility. I mostly want to use this to finish up edges and such on things I cut on the bandsaw and whatnot and shape pieces of wood, handles for homemade clamps is one application that comes to mind.

[Rick Lizek]

50 hz isn't going to last long on 60 hz. One of the guys in our shop bought a drill in England and with intermittent use it failed eventually. It will run hotter and faster as well.

[Mike Henderson]

50 hz isn't going to last long on 60 hz. One of the guys in our shop bought a drill in England and with intermittent use it failed eventually. It will run hotter and faster as well.
I think Finland is 50 Hz.

Mike

[Bill Bukovec]

When you turn the motor off and the speed gets slower, do you hear one "click" from the motor? The"click" is the sound of the centrifugal switch closing when the motor slows down.

If this is a split phase motor, your start windings may not be disconnecting as the motor speed up, causing all kinds of problem.

Someday I plan to write a motor thread that explains this in detail (with drawings).

Are you sure it's 50 hz and not 60? If it's a 50 I think you are out of luck.

Bill

[Dennis Ford]

The motor may have been built for intermittent use. If so; it will get hot when used for longer intervals.

[Dennis Aspö]

It should be a 50hz because we use 50hz here, I scavenged it from a locally bought tile cutting saw and we have 50hz electricity here in Finland. I think it would be difficult to find 60hz stuff here.

Also I'm back after all, that medical thing got postponed for later.

[Larry Browning]

Are you sure it's 50 hz and not 60? If it's a 50 I think you are out of luck.
Bill
You might have missed it, but the OP is in Finland, so I think a 50hz motor is a good thing.

[Dennis Aspö]

The motor may have been built for intermittent use. If so; it will get hot when used for longer intervals.

I think this is the reason TBH, hence the idea of improving the cooling, like a better/bigger fan and some cooling wanes or just attaching some lumps of metal as heatsinks, I wouldn't be using it very long at a time anyway. I think I will redesign the disk sander though and use a shaft and pillow block bearings, so I can easily replace the motor later on.

[Bill Bukovec]

Yes, I missed the Finland location.

Denis, If you post a picture of the wires with the end cap of the motor taken off, it may help.

Otherwise, good luck.

Bill

[Mike Schuch]

I have a table saw I could mount it in, it can take 12" blades so it's a possibility. I mostly want to use this to finish up edges and such on things I cut on the bandsaw and whatnot and shape pieces of wood, handles for homemade clamps is one application that comes to mind.

Rolling a dowel with the end against a disc sander is a quick and good way to round over the end of the dowel. I have done this many times. Disc sanders are also great for when you cut a curve just outside of the line then sand down to right on the line. For this type of work they are very handy. I think you would be much happier with a disc with sandpaper mounted on it in your table saw. The down side to a table saw is swapping in the disc and you have to remove the disc to change the paper.

A table adds a lot of versatility to a disc sander. You can sand precise angles if you have a table you can set at an angle (Or tilt the sanding disc to an angle in a table saw). Where you planning on crafting a tiltable table out of wood for your home made disc sander?

[Dennis Aspö]

Hmmm, what I think I will do is use this 3-phase 0.75kw motor I got for the disc sander, it's a 2850rpm motor. I don't think swapping out blades on the TS is going to be popular... This motor is way heavier and of a different design, despite not being much more powerful on paper.

I was going to use said motor to make a dust collector like Matthias Wandels small dust collector (bought the plans and all)... but perhaps I will use this 4kw moto of the same rpm that I got, for the DC instead, and size up the impeller design a bit. Its really quite hard to to decide. I figure sooner or later I wanted to use the big motor as a big DC, I had just imagined I'd build a smaller version first.