Lathe Motor

stan martin · Sep 4, 2006

I have a South Bend lathe made in the 40's. It has a brush type motor. The motor is acting up. It doesn't start sometimes, until I give the chuck a slight turn. My queation is: Do the bursh type motors use more current to operate? I can probably find a brush type motor if I do some looking, or should I stay away from this type of motor? Thanks for any info. Stan

stan martin · Sep 4, 2006

I have a South Bend lathe made in the 40's. It has a brush type motor. The motor is acting up. It doesn't start sometimes, until I give the chuck a slight turn. My queation is: Do the bursh type motors use more current to operate? I can probably find a brush type motor if I do some looking, or should I stay away from this type of motor? Thanks for any info. Stan

stan martin · Sep 4, 2006

I have a South Bend lathe made in the 40's. It has a brush type motor. The motor is acting up. It doesn't start sometimes, until I give the chuck a slight turn. My queation is: Do the bursh type motors use more current to operate? I can probably find a brush type motor if I do some looking, or should I stay away from this type of motor? Thanks for any info. Stan

Old Field Tech · Sep 4, 2006

Stan,
Pull the brushes and blow the carbon dust out of the motor (thru the brush holes).
If the brushes don't extend from the holder by at least, say a 1/4", I'm guessing here, then you need new brushes.
Also the commutator may be worn down and shorting.
If it were my machine, I'd yank the brushes and then pull the armature out. Clean the spaces between the copper bits with a piece of plastic. Reassamble the motor and manually spin it while feeding a 'white-stone' in one of the brush positions to re-smooth/surface the armature.
Sorry, I can't remember the exact name for the 'white-stone' but wherever you buy the brushes from will have the stone.
Blow out the grundge again and get er spinning

I hope that made SOME sense, I just can't describe it very well

Rod

Old Field Tech · Sep 4, 2006

Stan,
Pull the brushes and blow the carbon dust out of the motor (thru the brush holes).
If the brushes don't extend from the holder by at least, say a 1/4", I'm guessing here, then you need new brushes.
Also the commutator may be worn down and shorting.
If it were my machine, I'd yank the brushes and then pull the armature out. Clean the spaces between the copper bits with a piece of plastic. Reassamble the motor and manually spin it while feeding a 'white-stone' in one of the brush positions to re-smooth/surface the armature.
Sorry, I can't remember the exact name for the 'white-stone' but wherever you buy the brushes from will have the stone.
Blow out the grundge again and get er spinning

I hope that made SOME sense, I just can't describe it very well

Rod

Old Field Tech · Sep 4, 2006

Stan,
Pull the brushes and blow the carbon dust out of the motor (thru the brush holes).
If the brushes don't extend from the holder by at least, say a 1/4", I'm guessing here, then you need new brushes.
Also the commutator may be worn down and shorting.
If it were my machine, I'd yank the brushes and then pull the armature out. Clean the spaces between the copper bits with a piece of plastic. Reassamble the motor and manually spin it while feeding a 'white-stone' in one of the brush positions to re-smooth/surface the armature.
Sorry, I can't remember the exact name for the 'white-stone' but wherever you buy the brushes from will have the stone.
Blow out the grundge again and get er spinning

I hope that made SOME sense, I just can't describe it very well

Rod

jim rozen · Sep 4, 2006

This may be a repulsion induction type motor
and if the brushes are worn you might see this
effect. I would suggest you post this on the
vfd/converter/motors section as the folks there
are pretty knowledgeable. Likewise the SB
forum would be a good hit, there have been some
very lively discussions about SB lathe motors
there in the past.

Jim

jim rozen · Sep 4, 2006

This may be a repulsion induction type motor
and if the brushes are worn you might see this
effect. I would suggest you post this on the
vfd/converter/motors section as the folks there
are pretty knowledgeable. Likewise the SB
forum would be a good hit, there have been some
very lively discussions about SB lathe motors
there in the past.

Jim

jim rozen · Sep 4, 2006

This may be a repulsion induction type motor
and if the brushes are worn you might see this
effect. I would suggest you post this on the
vfd/converter/motors section as the folks there
are pretty knowledgeable. Likewise the SB
forum would be a good hit, there have been some
very lively discussions about SB lathe motors
there in the past.

Jim

6jaw · Sep 4, 2006

Single phase, capacitor start motor? There's a centrifugal switch that may not be returning to make a good connection in the start state (motor stopped). No amount of brush fiddling will help if you don't have continuity in the starting circuit. (switches the capacitor in to shift the voltage phase for starting)

John

6jaw · Sep 4, 2006

Single phase, capacitor start motor? There's a centrifugal switch that may not be returning to make a good connection in the start state (motor stopped). No amount of brush fiddling will help if you don't have continuity in the starting circuit. (switches the capacitor in to shift the voltage phase for starting)

John

6jaw · Sep 4, 2006

Single phase, capacitor start motor? There's a centrifugal switch that may not be returning to make a good connection in the start state (motor stopped). No amount of brush fiddling will help if you don't have continuity in the starting circuit. (switches the capacitor in to shift the voltage phase for starting)

John

chuckey · Sep 4, 2006

It is almost a certainty on a brush type motor of this vintage, that the brushes are worn out. This causes them to "rock" in their holder and loose contact plus the spring is fully extended, so the pressuure on the brushes in too low. I personaly use a piece of 400 grade wet and dry wrapped around a suitable piece of metal (6" rule?) to hold against the copper strips (commutator) to clean the black film of. If any of the strips are badly burnt, then the armature wil have to be turned between centres to true the commutator up. The traditional way of cleaning up the gaps between the copper strips, is to thin down the end of a broken hacksaw blade and use this to scrape out the copper dust between the strips. If you have a problem geting replacement brushes, get larger ones and "sand" them down with Ali oxide paper. The copper wire conections if fitted can be lengthened, by soldering an extension on and sleeving it.
frank

chuckey · Sep 4, 2006

It is almost a certainty on a brush type motor of this vintage, that the brushes are worn out. This causes them to "rock" in their holder and loose contact plus the spring is fully extended, so the pressuure on the brushes in too low. I personaly use a piece of 400 grade wet and dry wrapped around a suitable piece of metal (6" rule?) to hold against the copper strips (commutator) to clean the black film of. If any of the strips are badly burnt, then the armature wil have to be turned between centres to true the commutator up. The traditional way of cleaning up the gaps between the copper strips, is to thin down the end of a broken hacksaw blade and use this to scrape out the copper dust between the strips. If you have a problem geting replacement brushes, get larger ones and "sand" them down with Ali oxide paper. The copper wire conections if fitted can be lengthened, by soldering an extension on and sleeving it.
frank

chuckey · Sep 4, 2006

It is almost a certainty on a brush type motor of this vintage, that the brushes are worn out. This causes them to "rock" in their holder and loose contact plus the spring is fully extended, so the pressuure on the brushes in too low. I personaly use a piece of 400 grade wet and dry wrapped around a suitable piece of metal (6" rule?) to hold against the copper strips (commutator) to clean the black film of. If any of the strips are badly burnt, then the armature wil have to be turned between centres to true the commutator up. The traditional way of cleaning up the gaps between the copper strips, is to thin down the end of a broken hacksaw blade and use this to scrape out the copper dust between the strips. If you have a problem geting replacement brushes, get larger ones and "sand" them down with Ali oxide paper. The copper wire conections if fitted can be lengthened, by soldering an extension on and sleeving it.
frank

Andreas · Sep 4, 2006

I've heard that commutators should not be sanded since pieces of the abrasive material gets stuck in the copper. They should be lathed, preferably with diamond. The stuff between the copper strips is micanit, a quite hard stuff. This should be lower than the copper, that is done by grinding a hacksaw blad narrower so it only takes the isolation away. Sanding the commutator will not make it perfectly round, which it needs to be to function properly.

Andreas Wahlberg

Andreas · Sep 4, 2006

I've heard that commutators should not be sanded since pieces of the abrasive material gets stuck in the copper. They should be lathed, preferably with diamond. The stuff between the copper strips is micanit, a quite hard stuff. This should be lower than the copper, that is done by grinding a hacksaw blad narrower so it only takes the isolation away. Sanding the commutator will not make it perfectly round, which it needs to be to function properly.

Andreas Wahlberg

Andreas · Sep 4, 2006

I've heard that commutators should not be sanded since pieces of the abrasive material gets stuck in the copper. They should be lathed, preferably with diamond. The stuff between the copper strips is micanit, a quite hard stuff. This should be lower than the copper, that is done by grinding a hacksaw blad narrower so it only takes the isolation away. Sanding the commutator will not make it perfectly round, which it needs to be to function properly.

Andreas Wahlberg

gmatov · Sep 5, 2006

Commutators can be sanded but not with aluminum oxide cloth. The granules are conductive.

They CAN be stoned, but again not with an Alox stone.

If the micarta separators, the insulation, stick up, the have to be undercut to prevent brush bounce. That makes for arcing. And, if you do that, you should also bevel both sides of each bar.

I've stoned and beveled quite a few of them. Stoning them, even with a mask on, for you smokers, which I was and am, makes your cig smoke taste like inhaling honey for about 12 hours. Sickening, in other words. Masks weren't worth a damn.

Cheers,

George

gmatov · Sep 5, 2006

Commutators can be sanded but not with aluminum oxide cloth. The granules are conductive.

They CAN be stoned, but again not with an Alox stone.

If the micarta separators, the insulation, stick up, the have to be undercut to prevent brush bounce. That makes for arcing. And, if you do that, you should also bevel both sides of each bar.

I've stoned and beveled quite a few of them. Stoning them, even with a mask on, for you smokers, which I was and am, makes your cig smoke taste like inhaling honey for about 12 hours. Sickening, in other words. Masks weren't worth a damn.

Cheers,

George

Lathe Motor

Aluminum

Aluminum

Aluminum

Aluminum

Aluminum

Aluminum

Diamond

Diamond

Diamond

Aluminum

Aluminum

Aluminum

Stainless

Stainless

Stainless

Aluminum

Aluminum

Aluminum

Diamond

Diamond

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