Newbie electric motor questions

PIndelicato

PIndelicato

Joined
Sep 16, 2002
Messages
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I've been sort of keeping one eye open for used electric motors thinking someday about building a NWGS and/or disk. When I look at the KMG or similar products online, I see a 1 or 1.5 HP motor as max for a 110V circuit, and then 2-3 HP motors requiring 220V. However, I've seen a couple of used Baldor motors that are 3 HP/110V/single phase.

I would be grateful if someone can fill in the gaps for me and explain what I might be seeing and/or what to look for. Would this type of motor I'm seeing be a good choice?
 
1.5 is the limit with 110. I just upgraded to a 2hp and it is 220. Do not even look at a 1hp. 1.5 and up is where it is at for a KMG or a clone of one. I looked for months for a used 2hp Lesson with no luck. Ended up purchasing a new one for $199, best price I have found.
 
3 phase + VFD is the way to go, if you can save. 3 Phase motors are much cheaper, more honestly rated, more efficient and with VFD, you get variable RPMs and less tangible goodies like programmable spin up/down time and ability to reverse.

You will be getting that "stimulus' check , right ? Use it to stimulate yer hobby :) !
 
There are 746W in 1HP, so provided a motor could reach 100% efficiency, you would be able to get 3.7HP out of a 25A circuit @ 110V. Most motors are more in the 60% efficiency realm, putting you just over 2HP on a 25A circuit. Look at how many amps the motor draws to get an idea of if they are totally exagerating the HP. On a 15A circuit, you'd have to get a 70% efficient motor to even reach 1.5HP.

After saying all that, I don't think you need anything larger than 2HP, I've worked only on 1.5 and 2hp grinders and had not problems with bogging down the motor. I think most people that bog down motors are putting a lot of surface area on a platen and pressing hard. Just let up a little bit, or hog your steel with a wheel first and you'll be fine.
 
It just draws twice as many amps at 115V. You'll need a 30A circuit to run it on 110, which means you'd probably have to put it in yourself. Most houses don't have anything larger than 20/25A 110.

That's a lot of money for a motor, especially considering you can get a nice motor from Rob with a VFD for less. You can get a 3HP setup from him with a VFD for the same money.
 
I'm sorry AcridSaint, I should have clarified that link was just for an example of specifications. I've seen a couple similar to that one, one supposedly brand new for ~$150, and another similar one for maybe ~$75 refurbed.

I only have 110 in the garage and doubt I would upgrade to 220 nor am I handy with electricity. I just thought these seemed like reasonable buys, but was confused by the apparent HP rating of these vs. what I had seen at places such as Beaumont Metal Works.

Not in any hurry here, just keeping one eye open to see what pops up and want to know what the differences are so I don't make a mistake in the future.
 
The problem you'll run into is the amps. Your garage probably has 14Ga or 12Ga wire in it and won't be rated for a 30A circuit, so if you want to go that high you'll have to pull new wire. If you're pulling new wire, there's really no point in not running 220 instead.

Also, according to what I understand, if you want to run a vfd on 110V, you'll be limited to about 1.5HP. Rob Frink posted somewhere on here in more detail about it.

The thing to keep in mind is that the volts don't really limit your HP or wattage, it's how many amps you can multiply by. 220 won't give "more power", you just get more total watts because of the amps.
 
It is extremely rare to find a circuit in straight 110 of greater than 20 amps. If you are going to go to the trouble of putting in an additional circuit, the extra cost to go to 220 is very small, so there is no sense to not just put in a 220 outlet...
 
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