Electric motor question

[Witchgrass]

Hey guys, I’ve got a Homemade wood lathe that I’m fixin to pull out of storage. It has a 1HP, 1732 RPM electric motor on it. It has a couple of step up/down pulleys that work OK, but I’m wanting to add a rheostat type controller to slow it down. I don’t no know how these things are rated. Can anybody help me out with info on what kind/switch to look for?
Thanks,

[Arrow-Tek]

They will probably be rated by voltage and amperage for the motor your trying to control.

[Reel Screamer]

If it’s not a shaded pole type motor I believe it won’t work that way. Your pulley system or change to a gear reduction type motor.

[Witchgrass]

If it’s not a shaded pole type motor I believe it won’t work that way. Your pulley system or change to a gear reduction type motor.

I Kinda follow that..
When I built this lathe, 20 plus years ago, it worked mostly, but was still spinning a little fast for certain work. I added a ceiling fan switch, to slow it down, which it did, but at slow speeds, it lost all torque when I would dig in with the bowl gouge. The theory, was correct (I believe), but wrong use of the (ceiling fan) switch. So I’m just trying to figure out what switch will give me high enough torque at slow speeds.

[Tom]

DC motor is the only way to get low speed / high torque. this is not a switch issue but the application for the motor you have and what you want is incorrect. You can get a good DC motor for not too much money.

to vary the speed of an AC motor you need to vary the input frequency and not the voltage so it is much more complex than a standard rheostat.

[175gr7.62]

Hey guys, I’ve got a Homemade wood lathe that I’m fixin to pull out of storage. It has a 1HP, 1732 RPM electric motor on it. It has a couple of step up/down pulleys that work OK, but I’m wanting to add a rheostat type controller to slow it down. I don’t no know how these things are rated. Can anybody help me out with info on what kind/switch to look for?
Thanks,

There are 2 ways to change the speed in an AC motor. You can vary the frequency or the voltage with resistance. The normal way to do it is by changing the frequency. It is more efficient but typically costs more than a rheostat. The problem with reducing the voltage to control speed comes from "slip". At the rated voltage/frequency the motor slip is pretty close to zero. When you reduce the voltage you are reducing power to motor. The motor poles don't receive enough power to produce sufficient EMF and the motor slows or stalls pretty easily under load.....the slip increases.

You can get AC motors with multiple taps that work better with reduced voltage but you just get step functions in speed.....basically how a ceiling fan works.

The only way to really keep your torque and reduce the speed though is with a variable frequency drive. You can get an Amazon quality one starting at about $100.

[Witchgrass]

There are 2 ways to change the speed in an AC motor. You can vary the frequency or the voltage with resistance. The normal way to do it is by changing the frequency. It is more efficient but typically costs more than a rheostat. The problem with reducing the voltage to control speed comes from "slip". At the rated voltage/frequency the motor slip is pretty close to zero. When you reduce the voltage you are reducing power to motor. The motor poles don't receive enough power to produce sufficient EMF and the motor slows or stalls pretty easily under load.....the slip increases.

You can get AC motors with multiple taps that work better with reduced voltage but you just get step functions in speed.....basically how a ceiling fan works.

The only way to really keep your torque and reduce the speed though is with a variable frequency drive. You can get an Amazon quality one starting at about $100.

^^^^Thank you! This is what I was needing. You the MAN!

[mudkat]

https://www.harborfreight.com/router-speed-control-43060.html

you could try one of these and see if it works i have one i used with a inline die grinder and it worked ok

[Witchgrass]

There are 2 ways to change the speed in an AC motor. You can vary the frequency or the voltage with resistance. The normal way to do it is by changing the frequency. It is more efficient but typically costs more than a rheostat. The problem with reducing the voltage to control speed comes from "slip". At the rated voltage/frequency the motor slip is pretty close to zero. When you reduce the voltage you are reducing power to motor. The motor poles don't receive enough power to produce sufficient EMF and the motor slows or stalls pretty easily under load.....the slip increases.

You can get AC motors with multiple taps that work better with reduced voltage but you just get step functions in speed.....basically how a ceiling fan works.

The only way to really keep your torque and reduce the speed though is with a variable frequency drive. You can get an Amazon quality one starting at about $100.

Is this what you are referring to?
Most of these show to be 220v, and lots of them are for 3PH. My motor is a 110v, 1PH. If this is not what you are referring to, could you possibly post a link to one?
Thanks again,

[HogHunter34]

Your choices for 110v single phase VFDs will probably be limited. Most VFDs are built for 3-phase
I think they are out there but might be HP limited or FLA limited. Keep searching

[RifleBowPistol]

Years ago, I went to Woodcraft Supply and bought a controller for electric motors. At the time, I was using it or my electric 1/4" die grinder. It only had on and off. I needed to slow it down. That controller worked great for that motor.

I have a Chinese made small mill, lathe and drill press. I has two motors, one for the lathe, then one for the mill head. I mainly use that as a lathe, since I have a Bridgeport 2 hp mill now. I think the lowest speed I can get out of the lathe is something like 600 rpm. Which is way too fast for harder metals, it will burn bits up quickly. I tried my controller, that I bought from Woodcrafters years ago. The cheap Chinese motor on my lathe, will not do anything with that variable speed controller inline, unless I switch to full power, basically no resistor in line. I would need to change the motor out, to get it to work. I thought about trying to make some different size pulleys or get some different size pulleys made. I really need a larger lathe, so that's on my list of next large tool to buy. I want one with at least a 48" bed. I want to be able to do all of my rifle barrels myself, once I get that lathe.

You can try one of those rheostats/variable speed controllers, it may work for your wood lathe, that's what Woodcraft sells them for. But if your lathe has a cheap Chinese motor, like my metal lathe, it is not going to work.

[Witchgrass]

I just heard back from Woodcrafters. They do not sell speed controllers, and least not anymore. The motor that I have is probably not a Chinese made motor. I pulled it out of a scrap yard in the mid 90s. Do know the brand off hand, but it’s a HD motor. As I mentioned the first post, I originally wired it up to a ceiling fan switch to slow it down, but it looses all torque when it looses speed. Maybe I ought to go with a step pulley system since I can’t seem to find the electronic controller to make it work.

[banzai]

Harbor Freight sells a router speed controller for $15. It runs single phase, 120 volt., up to 8 amps which should cover your 1 hp.

https://www.harborfreight.com/router-speed-control-43060.html

[Jason Fry]

As stated, DC drive or an AC motor and VFD are the ways to go.

For the VFD, you can use 110 or 220 single phase input, and the VFD puts out three phase. You need a 3 phase motor to do it that way.

This is a very common question in the world of knife grinders, and I have never seen any other answer besides these two options.

[Witchgrass]

As stated, DC drive or an AC motor and VFD are the ways to go.

For the VFD, you can use 110 or 220 single phase input, and the VFD puts out three phase. You need a 3 phase motor to do it that way.

This is a very common question in the world of knife grinders, and I have never seen any other answer besides these two options.

Any chance that you could post a link to a website, or a direct model motor that you are suggesting?
TIA