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View fumehappy's profile

how hot is the motor supposed to get?

by fumehappy
posted 04-25-2013 04:04 AM


33 replies so far

View murch's profile

murch

1182 posts in 1343 days


#1 posted 04-25-2013 07:37 AM

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 .

-- A family man has photos in his wallet where his money used to be.

View rustfever's profile

rustfever

633 posts in 2029 days


#2 posted 04-25-2013 09:46 AM

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

-- Rustfever, Central California

View EEngineer's profile

EEngineer

903 posts in 2332 days


#3 posted 04-25-2013 10:09 AM

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.

-- "Find out what you cannot do and then go do it!"

View Shawn Masterson's profile

Shawn Masterson

1262 posts in 667 days


#4 posted 04-25-2013 11:13 AM

Put a meter on it and check the amp draw

View alph's profile

alph

11 posts in 581 days


#5 posted 04-25-2013 11:54 AM

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.

-- alberto angelo

View fumehappy's profile

fumehappy

115 posts in 971 days


#6 posted 04-25-2013 01:12 PM

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!

View fumehappy's profile

fumehappy

115 posts in 971 days


#7 posted 04-25-2013 01:12 PM

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

View dhazelton's profile

dhazelton

1240 posts in 1015 days


#8 posted 04-25-2013 01:58 PM

”...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.

View fumehappy's profile

fumehappy

115 posts in 971 days


#9 posted 04-25-2013 02:05 PM

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

View dhazelton's profile

dhazelton

1240 posts in 1015 days


#10 posted 04-25-2013 02:15 PM

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.

View REO's profile

REO

643 posts in 793 days


#11 posted 04-25-2013 02:37 PM

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.

View 8iowa's profile

8iowa

1489 posts in 2480 days


#12 posted 04-25-2013 02:47 PM

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.

-- "Heaven is North of the Bridge"

View dhazelton's profile

dhazelton

1240 posts in 1015 days


#13 posted 04-25-2013 03:36 PM

@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.

View TheDane's profile

TheDane

3931 posts in 2382 days


#14 posted 04-25-2013 03:40 PM

+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.

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

View fumehappy's profile

fumehappy

115 posts in 971 days


#15 posted 04-25-2013 03:58 PM

@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

View fumehappy's profile

fumehappy

115 posts in 971 days


#16 posted 04-25-2013 04:17 PM

@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.

View dhazelton's profile

dhazelton

1240 posts in 1015 days


#17 posted 04-25-2013 07:08 PM

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

View REO's profile

REO

643 posts in 793 days


#18 posted 04-25-2013 10:52 PM

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.

View MNgary's profile

MNgary

235 posts in 1136 days


#19 posted 04-25-2013 11:19 PM

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.

-- I dream of the world where a duck can cross the road and no one asks why.

View RussellAP's profile

RussellAP

2963 posts in 1005 days


#20 posted 04-25-2013 11:29 PM

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

-- A positive attitude will take you much further than positive thinking ever will.

View Rick M.'s profile

Rick M.

4322 posts in 1099 days


#21 posted 04-26-2013 03:31 AM

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

-- |Statistics show that 100% of people bitten by a snake were close to it.|

View EEngineer's profile

EEngineer

903 posts in 2332 days


#22 posted 04-26-2013 11:19 AM

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!

-- "Find out what you cannot do and then go do it!"

View fumehappy's profile

fumehappy

115 posts in 971 days


#23 posted 05-02-2013 06:06 PM

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

View ChuckV's profile

ChuckV

2460 posts in 2246 days


#24 posted 05-02-2013 06:59 PM

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

-- “While the world with closed eyes sleeps, The sky knows and weeps - steel rain. ” ― Nathan Bell

View fumehappy's profile

fumehappy

115 posts in 971 days


#25 posted 05-03-2013 12:18 PM

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

View MrFid's profile

MrFid

560 posts in 623 days


#26 posted 05-03-2013 12:23 PM

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.

-- Bailey F - Eastern Mass.

View BinghamtonEd's profile

BinghamtonEd

1521 posts in 1088 days


#27 posted 05-03-2013 12:41 PM

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

-- - The mightiest oak in the forest is just a little nut that held its ground.

View fumehappy's profile

fumehappy

115 posts in 971 days


#28 posted 05-03-2013 01:57 PM

View fumehappy's profile

fumehappy

115 posts in 971 days


#29 posted 05-03-2013 02:04 PM

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

View TorxNut's profile

TorxNut

58 posts in 616 days


#30 posted 05-03-2013 02:26 PM

A success story! Congrats!

Bill

View dhazelton's profile

dhazelton

1240 posts in 1015 days


#31 posted 05-03-2013 05:56 PM

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?

View fumehappy's profile

fumehappy

115 posts in 971 days


#32 posted 05-05-2013 10:23 PM

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. :).

View dhazelton's profile

dhazelton

1240 posts in 1015 days


#33 posted 05-06-2013 02:24 PM

Saving the world from one more Chinese tool – fantastic!

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