# how hot is the motor supposed to get?



## fumehappy (Mar 26, 2012)

So i'm kinda new to the old wood turning thing. i've had an old montgomery ward lathe kicking around forever. found a motor for it last summer, 1/3 horse, 1725 RPm. This matches the spec of what originally came with the lathe. Today I was working on my lathe bench and was doing a mock-up to confirm it was going to work as planned. Motor ran cool with nothing attached, and then with the belt on the empty lathe. But once I put a piece of wood in, that sucker got too hot to touch within about a minute of turning time. A bit of smell too, but no smoke. Motor is old, probably from the 40's or 50's, pics to follow shortly. It says ball bearings on the sides where the arbors are bushed, and I don't see anywhere to oil it. 
Are they supposed to get that hot? It does spin freely with no load, and when you plug it in, it just hums for a bit, and then usually needs a spin to get going. 
Thanks!
~John


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## murch (Mar 20, 2011)

Mine is a 1/2 hp. It only gets hot enough that you're glad to put your hands on it on a frosty morning.

Seriously though, electrics is not my area but if a motor is too hot to touch in such a short space of time it's
probably on it's last legs.
Hard to know with something that old though. Maybe it's just loosening itself out and will be fine after some 
cleaning and maintenance .


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## rustfever (May 3, 2009)

I have heard somewhere that an electric motor should run at a temperature of not over 40F above ambient temp


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## EEngineer (Jul 4, 2008)

when you plug it in, it just hums for a bit, and then usually needs a spin to get going.

This is an indication there is something wrong! If it is capacitor start, check the cap and the centrifugal switch to make sure they are operating. If it has a separate start winding, again, check the centrifugal switch. Are you sure that the motor is ever getting up to full running speed?

Motors are very rugged beasts. You probably have not destroyed it yet running it like this but it will die eventually unless you address the starting issue.


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## shawnmasterson (Jan 24, 2013)

Put a meter on it and check the amp draw


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## alph (Apr 20, 2013)

get a new one, they're only $50 at harbor frieght. if you have to "spin" it to get it going, it sounds like the bearings are all gummed up, if it's 50years old, you got your monies worth out of it.


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## fumehappy (Mar 26, 2012)

EEngineer, what would be the best way to do that? I have a multimeter available to me to check the amperage. I"ve never worked on a motor before, but now is a good a time as any to start…



















Thanks!


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## fumehappy (Mar 26, 2012)

To clarify, there is a cover on the bearings, I just took it off to inspect them.


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## dhazelton (Feb 11, 2012)

"...if it's 50years old, you got your monies worth out of it." Never. I'd rather spend $50 to refurbish a 50 year old American motor and understand how it works than buy a new Chinese one that will probably burn out in five. These motors are simple to disassemble. Basically once you take those four square nuts off the whole affair just pulls apart. If the bearings are in good shape and don't feel notchy when you turn the inner race I would just clean and repack. There's a motor shop near you somewhere, just have to look in the phone book. You can take the capacitor to them to check (the cardboard covered doodad in the base) and they can sell you a new one. The wiring in the base is just wire nutted together I believe so it's easy to disassemble. Only thing to do with the windings is blow all the dust out or use some CRC electrical cleaner. I would wire in a new 20 amp switch and grounded cord on the front of the lathe stand so you don't have to use the toggle on the motor base. Make sure you mark the top of the end housing as I think they only go together one way. If it's running hot you may have the belt too tight which stresses and overheats the bearings. Just pull it apart and clean and repack everything and check the wiring and test it - you have nothing to lose.


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## fumehappy (Mar 26, 2012)

Yeah, i've been doing some research since I posted the pics a little while ago. I want to try the rebuild for that reason, and to learn something for myself. Found this thread on a different site, and I'm going to work off that as a template.

Motor Rebuild


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## dhazelton (Feb 11, 2012)

Your motor is significantly easier than that one - I don't think it has that centrifugal switch assembly for one, and the capacitor is in the base with the rest of the wiring. I redid the exact same motor a couple of years ago, but it ran fine to begin with. It was just packed with sawdust and I replaced the bearings because mine were replacement sealed bearings that felt dry (that's why I like the original type like you have). You really only need to take off the end where your pulley is, pull out the inner armature and shaft and leave the outer windings alone in the housing. You may find nothing wrong with your capacitor but it may be a loose connection in the base. Have fun.


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## REO (Sep 20, 2012)

check your pulley diameters, and rpms. you may be high on the spindle rpm and that would make it work harder. Split phase motors have no capacitor or start winding switch the start winding and main windings stay on all the time these motors are for low torque applications. kind of self regulating loads like fans and grinders. you could use it but you would have to limit yourself to extremely light cuts.


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## 8iowa (Feb 7, 2008)

dhazelton is spot on. Take it to a motor shop for a little TLC. This motor is worth the expense. I would probably invest in a new set of bearings while it's at the shop.

I suspect that it is rated 55 degree C temperature rise over a 40 degree C ambient. A 40 degree C ambient translates to a maximum "room" temperature of 104 degrees F. Add the full load temperature rise of the motor (55 degrees C) and you get a maximum temperature inside the motor of 203 degrees F. The outside temperature of the motor won't be that hot, but since the human limit is around 125 to 150 degrees the motor will be too hot to keep your hands on it. However, the motor is still just fine.


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## dhazelton (Feb 11, 2012)

@Reo, there is still a little cardboard covered capacitor in the bases of these. If not a start capacitor what is it? I agree with the point that lathe work is hard on a motor and 1/3 HP is not much. Mine powers an old Sears 6×48 belt sander with disc though and it's fine for that.


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## TheDane (May 15, 2008)

+1 for taking it to a motor shop. They can either rebuild your motor or make you a good deal on a rebuilt motor they may have sitting on the shelf. The shop I used to deal with (in La Crosse, WI) put a decent warranty on their work.


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## fumehappy (Mar 26, 2012)

@Reo,
Checking google image search for similiar lathes, the motor pulley does appear significantly smaller. This is just one I picked up at a flea market, so I know it's not original. I have a smaller step pulley I can try and put on there when I do the cleanout.
Thanks!
~John


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## fumehappy (Mar 26, 2012)

@dhazelton,
Is there a recommended method for cleaning this type of bearing/ and or grease I should use? They are still smooth with no play.
Thanks!
John.


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## dhazelton (Feb 11, 2012)

I would probably soak them in kerosene or some kind of parts cleaner or degreaser, clean up with a toothbrush, blow dry and repack with ordinary axle or bearing grease from the auto parts store. Does your lathe fave a stepped pulley on it? If so either the motor also had a stepped pulley or was on a sliding mount and tension was kept just by the motor's weight. This is the only MW lathe I can find on the Vintage Machinery site publication reprint section. It doesn't reference pulley sizes, just their part number. If you look in the Craftsman section and find a similar lathe, Sears was good about giving you pulley sizes for whatever RPM motor you had on hand.

http://www.vintagemachinery.org/pubs/detail.aspx?id=2845


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## REO (Sep 20, 2012)

dh I am not aware of a split phase motor with a capacitor. there are several configurations of capacitor use in motors. Splitting the phase by installing the start windings 90 degrees out of sync is the way the cap was kept out of the circuit. I would imagine that a properly sized cap the torque of the motor could be increased but then it would not be split phase but instead capacitor run. In order to clean and lubricate the bearings you will need to remove the seal from one side of the bearing both sides would be better. pack the bearing as ou would a wheel bearing but wipe off the excess remaining outside of the bearing cage before reinstalling the seals. Use a good quality high temp grease for repacking. Typically these bearings are permanently lubricated and are replaced instead of servicing. care must be taken to completely remove the old grease before repacking because if incompatibilities in grease.I would suspect that new these bearings would run less than 15 dollars each.


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## MNgary (Oct 13, 2011)

If I had a lathe with a motor that only overheats when there is pressure on the headstock, I would look at bearings and bushings in the headstock before opening the motor.


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## RussellAP (Feb 21, 2012)

This might be a good time to think about an upgrade. Penn State has some at a pretty reasonable price. I can't vouch for how good they are, but maybe someone else can chime in.

http://www.pennstateind.com/store/mini-lathes.html


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## wormil (Nov 19, 2011)

Fractional HP motors are common and cheap, I wouldn't put much money into fixing it. Do what I did and switch over to a variable speed DC motor, cost me $10. I've since moved that motor to a Sears/King Seeley lathe, probably not too dissimilar to your MW.

http://lumberjocks.com/wormil/blog/34487


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## EEngineer (Jul 4, 2008)

fumehappy -

I've rebuilt a number of motors in my day. I think it is fun and I agree with dhazelton - the old motors were built better and are well worth rebuilding.

over at OWWM, I found a manual for a motor that looks a lot like yours. This manual covers a split-phase (no capacitor) with centrifugal switch for starting. The exploded drawing should get you started.

Whether capacitor start or split-phase, that centrifugal switch is the most likely culprit. I have found several times that they are just packed with sawdust and cannot make contact. It leads to exactly the symptoms you described: shaft turns easily (no bearing issues) but you must give it a slight turn to make it start.

The tutorial you referenced is good. Heed the tip about marking the bells to get them back on the way they were oriented in the first place!


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## fumehappy (Mar 26, 2012)

No shop time for the last week and a half… but tonight I got a date with my motor


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## 280305 (Sep 28, 2008)

Lucky man. Not just any motor, but a *hot *motor!


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## fumehappy (Mar 26, 2012)

Date went well… I made her purr…pics to follow later.


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## MrFid (Mar 9, 2013)

For bearing grease I use Phil Wood, comes in a green tube. You can definitely find it at bicycle stores. I am a cyclist myself, and that's what I use on bike bearings. Maybe it's different for a lathe, but the stuff is great.


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## BinghamtonEd (Nov 30, 2011)

Oh come on! You gotta kiss and tell. What was the problem?


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## fumehappy (Mar 26, 2012)




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## fumehappy (Mar 26, 2012)

I think it was a combination of factors.
1 wrong pulley size. With the original pulley I used the lathe went stupid fast. The inside was somewhat dusty and the contacts needed a light sanding. I also cleaned up the on/off switch contacts as they were heavily oxidized. She turns on instantly now and I used it for half an hour or so. After actual use the motor was cool. Hardly above ambient. Thanks guys!
I think I have to reverse the polarity as the wood I was turning kept breaking loose and spinning on the point


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## TorxNut (Mar 16, 2013)

A success story! Congrats!

Bill


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## dhazelton (Feb 11, 2012)

Awesome! I wouldn't reverse polarity, I'd turn the motor around. But that may not work for your mount. Is it hanging below the lathe or set up behind?


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## fumehappy (Mar 26, 2012)

Hanging below. I was able to reverse the mount and drive it in the correct direction. Result? I turned a piece of firewood into a much needed paring chisel handle. .


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## dhazelton (Feb 11, 2012)

Saving the world from one more Chinese tool - fantastic!


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