Compressor Motor for Belt Grinder?

G

Greebe

Joined
Aug 2, 2009
Messages
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I am putting together a belt grinder and was looking for a motor. I was hoping to find a used one because I am limited on funds right now. Anyways not being able to find a used motor I am trying to find something that wont break the piggy bank.

I did some searching about compressor motor's and got conflicting results. Some say they are great while others say don't use them.

Anyways I found a 2HP Compressor Motor at Tractor Supply for only $130. Why are they so much cheaper than general purpose motors? I know it is not enclosed, but I could mount it under the bench to keep it from getting ruined.

So what do you guys think about using these for belt grinders? It seems like if it can run my compressor that it should be able to run a grinder.

One thing that I saw mentioned from a few people was that compressor motor's are not meant to be run for long periods of time, since most compressors only cycle on and off. I would disagree with this though as I have a 60 gal compressor with a 5 hp motor that will run for hours at a time when I am doing large batches of work in the blast cabinet or when using certain air tools for extended periods of time. Been doing this for a long time without any problems.

Anyways let me know what you guys think.

Thanks
Greebe
 
It mostly has to do with being totally enclosed. Putting it under the bench won't really help much to be honest.

Keep an eye on eBay and craigslist and you may find better deals.

-d
 
Thanks. I have spent a lot of time looking on ebay. Deals aren't really to be found anymore on ebay. Everyone wants new prices for used stuff these days. It seems like with the economy taking a dump, people all of a sudden think their old stuff is worth a lot more.

You don't think that if the motor was enclosed under the bench that it would stay clean?

Thanks
Greebe
 
One good reason to fill out your profile is that we would know where you are.

Someone could steer you to a local scrap yard or surplus center near you where a TEFC motor might be found for a song...........if they knew where that was.
 
I have been using a compressor motor on my grinder for a few years. I occasionally blow it out (shut off) and I cut a piece of air conditioner filter to fit over the vents on the motor to help keep metal dust out. It has shorted out once, but I just shut it down as fast as I could. I had to tear it apart and do a good cleaning, but it is still running today. Here is the catch: I paid $0 for it and would be pretty nervous about dropping $130 on one when that would get you most of the way to a tefc motor. Tell everyone you know you are looking for a 1.5-2HP motor, and there is a good chance you find one for very little or maybe nothing. Good luck.

-Mike
 
Yeah, compressor motors are kind of iffy and there is not a lot of useful info about them online. Manufacturers and retailers will of course say that they are good to rated horsepower and are high quality. Some won't even list whether it's rated for continuous duty or not. The only way they often distinguish a compressor motor is "designed for high torque startup applications." Well jeez, that sounds like something that would make a motor cost more, not half as much.

They are not created equal. Watch out for motors rated for "peak horsepower." This is total crap, usually they are way underpowered.

General duty open frame drip proof motors cost nearly as much as tefc new most of the time, so I can't see that being most of the cost difference.

Some compressor motors seem to really kick ass however, and there are lots of hydraulic presses that use them, for instance. It's an inconsistent and shady field of products and still puzzles me a bit.

Otherwise, these motors are very often 3450 or 3600 rpm which is a little fast for a belt grinder motor, especially if single speed. Just something to consider if you can help it.
 
Having started out my knifemaking career using "open" motors, I can speak from experience. At first I couldn't understand why everyone was telling me to purchase a TEFC motor that was 2-3X as much.....and even after burning up two motors, I was still too hard headed to listen. After burning up the third "open" motor in a year, I decided that I wasn't so smart, and spent the money on a TEFC motor....and that motor is still in service today.....nearly 25 years later!

Compressor motors have three major flaws when considering them for belt grinder applications....
1. Open frame (already mentioned)
2. They are built specifically for intermittent use (will not hold up long with continuous use)
3. They generally only come in 3450rpm, which I consider too fast for a grinder application (of course it could be slowed with the proper pulley sizes)
 
Hi - I have firsthand experience using a 2HP compressor motor on a grinder.

I was able to start and run the motor on a 15A 110 circuit. I've seen 2HP TEFC motors blew 20A circuits at start. I could easily stall the compressor motor, where I have to put a good bit of effort into stalling my Bader and every other 2HP grinder I've worked on. Compressor motors generally don't have high efficiency ratings, meaning that in order to perform at 2HP, they need more power than their farm and industrial brethren.

I never had problems with metal dust blowing the motor up or any problems running the motor too long for its duty rating. I'm not saying it won't happen and I'm not saying that I think an ODP motor will last 20+ years under those conditions. I am saying that it probably won't break as soon as you turn it on ;)

If you are going to buy it, I'd at least get the specs off of it first and do a bit of online research.
 
Greebe said:
Thanks. I have spent a lot of time looking on ebay.
Deals aren't really to be found anymore on ebay. Everyone wants new prices for used stuff these days. It seems like with the economy taking a dump, people all of a sudden think their old stuff is worth a lot more.

You don't think that if the motor was enclosed under the bench that it would stay clean?

Thanks
Greebe
Click to expand...

I've noticed that, Garbage or Gold, depending on if you are buying or selling, but you can find some deals.

Shipping kills any deals for me, try local adverts. for pickup.

Try Wayne Coe, he quotes CONUS shipping included
 
I think there are still some deals on ebay. I got a new/old stock 1.5 Dayton TEFC 115/230, reversible for $100 shipped just 5 months ago. But I looked a lot. Keep looking for a TEFC. Any dust that doesn't go in my bucket, goes under the table.
 
Thanks, guys. I will pass on any open motor or compressor motor.

Indian George. What kind of error are you getting? I will try to PM you with my email address and see if that would work.
 
Greebe said:
Thanks, guys. I will pass on any open motor or compressor motor.

Indian George. What kind of error are you getting? I will try to PM you with my email address and see if that would work.
Click to expand...

Greebe,

You may have your motor by now, but I wanted to let you know that I proved my earlier point about ebay deals today. I picked up a new in box Dayton 2HP, TEFC, 115/208-230V, 1 Phase, reversible for $149 shipped. It sells at Amazon for about $400 shipped. I've only been looking for 3 days.

If you aren't finding anything, adjust your search methods. Don't just search "TEFC" or "1.5HP electric motor." Find the right category and try browsing the entire category with "buy it now" or "lowest price" or "ending soonest" as filters. Sometimes people don't list their items especially well, which is good because it keeps the traffic and interest down.

That being said, the industrial 3 phase motors are by far best deals going. This is most likely the last single phase motor I buy for any real money. A VFD or 3 phase rotary converter is in my future.
 
I'm still looking. I check ebay pretty frequently. It is getting pretty frustrating. I have found a few 1 hp 1750rpm TEFC motors in the $150 range. I wish I had some spare change to just go out an buy a new motor. Would a 1 hp motor be alright. There seems to be a pretty big price gap between a 1hp and a 1.5 hp motor.

Thanks again,
Greebe
 
alb1k said:
Greebe,

I just sent you an email with a link for a 1.5HP single phase you may like.
Click to expand...

I saw that one too but it appears to be an open frame motor. It does not appear to have the external fan cooled shroud and so forth. Maybe it is enclosed but it is hard to tell without a picture of the end.

Thanks
Greebe
 
Greebe said:
Deals aren't really to be found anymore on ebay. Everyone wants new prices for used stuff these days.
Click to expand...

I found that searching for a wide variety of different terms went a long way for me on Ebay. I got my new 2hp 3ph TEFC 56c frame motor for about $60 shipped and he had another one exactly like it that sold for $45 shipped. True in that case you have to use a VFD but I was seeing single phase ones too.
 
I went ahead and bought a 1 hp Leland-Faraday for $75. I hope that 1hp will be fine, but I got tired of looking so the heck with it that is what I will have. I figured that since it was an American made motor it might have a little more oomph than all the 1.5 hp Chinese motors on the market.

Thanks for the help.

Greebe
 
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