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Need input on a lathe motor

Tonyonehundred

Plastic
Joined
May 31, 2018
A friend of mine bought a new motor for his lathe I harbor frieght 2 HP compresser motor, and the old motor was a 3/4 HP induction. We hooked it up it works but gets hot after a few minutes. I thought maybe we have the wrong motor but he doesn’t think so. So thought I would come on here and ask someone if they could help me out with this
 
A friend of mine bought a new motor for his lathe I harbor frieght 2 HP compresser motor, and the old motor was a 3/4 HP induction. We hooked it up it works but gets hot after a few minutes. I thought maybe we have the wrong motor but he doesn’t think so. So thought I would come on here and ask someone if they could help me out with this
You do make it sound like he has the wrong motor, but there is no useful information in your question upon which to base advice.

Any motor from Harbor Freight is probably wrong, but maybe you know that.

Larry
 
Use a multi meter with amp clamp. Check volts and amps on hot legs. No or light load, the amps with be under whatever the motor is rated for. If amps are higher than its rating, then it would be overloaded.

If you have a hand held photo tach you can check its rated rpm's also.

Some motors are better than others, and may run hotter or colder.

For checking amps, you amp clamp one hot wire at a time. Clamping multiple, or neutral and ground wires at the same will give no reading, or bad reading.
 
Sorry Larry first time posting on here. I guess the main thing i wanted to know. Is a compresser motor capable of running a lathe? It seems to me that it wouldn’t. But the guy he bought it from said it would be fine to run a lathe with it. Didn’t know the difference between and induction motor and a compresser motor
 
Another consideration, follow the chain of parts that motor is turning. Does it spin free, or is it froze, locked up, dragging hard or other wise not spinning well.

Edit* a compressor motor is more heavy duty, so that by itself is fine. In fact those types of motors are better for gear head lathes as well.
 
It’s spinning great no bogging or anything. I am just not sure if that compresser motor can run a lathe is it to much of a load. I have checked Amps and voltage and it all checks out
 
It’s spinning great no bogging or anything. I am just not sure if that compresser motor can run a lathe is it to much of a load. I have checked Amps and voltage and it all checks out

See my edit, from my last post.

You can use a compressor motor on other things, but not a regular motor on compressor.
 
The Harbor Freight motor is also an induction motor. "Compressor" refers to the rated duty cycle (e.g. rated for partial duty like 15 minutes for every hour, or continuous duty) and service factor (e.g. maximum peak HP that can be delivered for a short duration). Compressor motors should be continuous duty and usually have a 1.15 or 1.25 service factor to give 15% or 25% more horsepower for short durations.

A lathe motor needs to be the right RPM, continuous duty, 1.15 or higher service factor and sized so that the power extraction rarely exceeds the nameplate HP rating.

Some others posted good advice, verify the installation - is the motor turning the proper RPM, is RPM too high, is there any binding or resistance in the equipment being driven?

Harbor Freight would not be my choice for a replacement motor, reputable motor manufacturers will provide detailed specifications including the expected winding temperature under load which allow the end user to verify that the motor is operating within specification.

Ryan
 
I agree with reidry, i'd just say in layman terms compressors are a harsh start for electric motors, as well as an uneven load throughout running operation, which is also pretty rough on an electric motor. Thats why electric motors for them are specified for compressor use. Compressor specified motors usually have no trouble running an even load, or easier start up aplications.
 
I've seen the insides of a few HF motors, I was less than impressed. Many "compressor" motors are wound so they have high starting torque, if you see SP in the HP rating it is a dead giveaway. Quite common to see small tank mounted compressors with motors listed as HP 5 SP, yet if you look at amperage rating it is clearly not a 5HP motor.
 








 
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