Replacement motor for my old lathe

Have you tried taking it to a local motor repair shop? They might be able to rewind it, put bearings in it and send you on your way. I have taken motors to the shop to be fixed figuring they were shot only to find that 50 years of dust and crud had clogged up the works. New bearing and a cleaning and I was on my way for not much money.

Michael no xx's in address

"Michael Cameron" wrote: (clip) I have taken motors to the shop to be fixed figuring they were shot only to find that 50 years of dust and crud had clogged up the works.(clip) ^^^^^^^^^^^^ I once drove 200 miles with a replacement motor for a printing press, only to find that the old one could be fixed with an air hose.

An aside: an old motor on a large, rugged frame is probably more durable than the newer, lighter one of the same horsepower.

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Horsepower is horsepower. Old motors tend to vibrate less but stall out at about the same place as a newer,smaller motor. My favorite replacement motor is a permanent magnet DC motor. I watch for them at the scrap yard I frequent, and would never pass up the opportunity to get one if it were 1/4 to 1 1/2 horsepower. I also watch for big variable voltage transformers. These two items plus a big bridge rectifier gives me variable speed. DC motors tend to be better balanced than induction motors. I suspect that when they turn the commutator etc that they also balance the rotor. Plus the push-pull magnetic field is missing. DC motors tend to be longer, and may not fit in your mounting area. The smoothest motors I have are three-phase motors on an old grinder. I think they were made by magicians, maybe Tesla himself. Older motors which are induction-repulsion (AC-only motor with brushes) are lovely, if you don't need to reverse the motor. To reverse them you have to take off the end plate, rotate a plate, and re-assemble the motor. VERY smooth starting but may or may not be smooth running. The fact that they are difficult to reverse is a problem on a lathe.

A NEMA book might be available at your local library. It will list all the standard frames, winding connections etc for any NEMA rated motor. You could look on your motor to see if it has some kind of NEMA markings.

I presume you have checked your capacitor?

brownnsharp

try taking it to an electrical motor repair shop... probably be less then getting a new motor and probably work better than a new one also.. if they cannot rebuild it they will tell you and also sdvise you of what kind of motor you need and will be able to guide you on to what you need..

What you say may be true in theory, but in my experience it is not the case. I had an old air compressor with a heavy cast iron body, 1 hp motor on it, and was going to"improve" it. The newer sheet steel bodied motor would not run the unit without bogging. I switched back, and all was well. At work, we have up to 50 to 60 year old B&S screw machines. I have replaced those old motors temporarily with same horsepower newer type, to allow the original motors to be rewound, and it consistently takes a newer type motor of 2 hp larger to do the same job without the machine bogging. The screw machine foreman is chomping at the bit waiting for his older motors to be returned and put back into service when they are in the shop. I have one of the older cast iron frame motors with the shaft snapped off even with the end housing laid back to change out the newer one on my phase converter. It takes two men to pick it up. I can pick up my modern 5 hp with one hand on the shaft. I think mass and diameter of the rotor is a key factor in these motors bogging less in use. Also I notice everyone says use these heavy motors for phase converter. I don't claim to be an expert here, these are my real-world experiences and observations, no offense meant to anyone.

RJ

I doubt you are going to find a motor shop to rebuild such a motor cost effectively, especially for rewinding. If the start cap went bad maybe they could fix it for a few bucks, otherwise a replacement motor from Grainger will run you $150 ~$175 for a 56 frame, if you go to a surplus place you can get one for much less. I would probably look for a 1 hp replacement.

Tony