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Discussion Starter #1
Hey guys I've got a speedaire 30 gallon unit with a 3 phase motor on it at my shop and I'm transporting to the house for home use and I'm looking for a 115/240 v motor to put in place of the 3 phase motor. Any recommendations? Here is the link of the compressor that I have.

Compressor, Air, 3.0 HP - Stationary Electric Air Compressors - Air Compressors and Vacuum Pumps - 4B237 : Grainger Industrial Supply

I found this 2 hp 120/240 motor on craigslist and it looks like a good possible swap candidate but I am going to be operating it on 115 volt and just wondering if this motor can handle the speedaire pump. It's rated at 1750 rmp's. I could buy a motor that is rated at 3450 rmp but it's new at grainger at lot more expensive.

Air compressor motor 2hp 115/230v ac - BRAND NEW

The price on this craigslist motor is right but I just want to make sure this is going to run my pump and not strain the motor too much or anything. I've got a welder and fabrication skills as well as some minor electrical making a motor bolt up and run is not an issue for me. What I don't know is if this motor is properly sized for the pump. It seems like it should be fine. It's the motor that came on the Dewalt D55580 twin 8 gallon tank emglo type compressors. My boss used to have one when I was doing construction for him and that was a solid compressor.

Anyhow any help or input is appreciated. Thanks
 

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Discussion Starter #2
Also, What is the benefit if any of a higher rpm motor? Can someone explain this? I know I see common rmp's of somewhere around 1700 and the other is somewhere around 3500. Pros? Cons? thanks in advance.
 

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Discussion Starter #4
The HP on the 3 Phase motor is 3 HP. The RPM rating on Graingers site for my compressor is 1020. The rpm of the motor I want to put on it is a 1750 and it's a 2 HP motor. I think it seems fairly closely matched and should operated okay but I'm no expert. Thoughts? I know I can make it happen but question is will I destroy my motor? The price is right on the motor so worst case scenario I run it and see how it does and replace it if necessary I guess.
 

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The RPM difference shouldn't make too much difference, you don't want to go above the 1750 tho. I would be more concerned with the HP being lower, but should work only pull a few more amps than the a 3 hp since it will be using most or all the 2 hp motor has. :D
 

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if you can get a 220v plug at home i would go with a 3hp 220v , but if 120v is all u can do i think you will be ok with the 2hp
 

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Discussion Starter #7
Yeah I'm planning on running a 220 circuit at the house anyway. (just gotta wait til my landlord goes outta town so I can get it all in) haha. So, Ideally I would get a 3 HP 1750 rpm motor from grainger but the price tag on that is upwards of 500 bucks. The 2HP one on CL is posted at $120 and seems a little flexible so it's really the price tag that's hanging me up at this point. Wish I could find a 3HP Craigslist motor deal.
 

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If you try to use a 2HP motor on a 3HP compressor, you will have to slow the compressor down to about 7-800 RPM instead of 1020, because at slower speeds compressors use less HP. This will require new pulleys on both the motor and compressor, since the motor speeds are different, and you have to change the compressor speed. Sounds like this will be a pain and add expense, so I would keep looking for a 3HP, 3500 RPM, 230V, single phase motor.
A 1750 RPM motor will last longer than a 3500 RPM one and run quieter as well. Just like with a compressor, slower equals longer life and is better.
 

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Discussion Starter #9
You mean keep looking for a 3HP 230v 1750 rpm motor yeah? I think that's what I'd like to do. If I get that Christmas bonus I'll go for a nice dayton. As far as the 1020 rpm rating of the compressor now and jumping to the 1750 rpm motor. Should I worry about swapping pulleys to get the rpms down to the 1020 or does it' really matter? Guess it depends on if I can find a 3hp single phase motor that the current pulley fits on or not otherwise if I have to get a pulley anyway then I could figure out the math to get the rpm's down if it's worth my time. Thoughts? thanks
 

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Seen the Lasers. I just stick to a straight edge or string line to line them up. Cheaper and just as good I think. String line has been used for many years as the way to align pulleys.
Leeson makes decent Motors.
 

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Discussion Starter #13
Finally dragged the thing home..

Thanks for the response sonny. String line should do just fine. So, I finally dragged the thing home today and didn't really have time to play with it but I did notice right off the bat that it has an Emerson motor on it and the rpm rating was 3450 which tells me this thing has already had at least one motor swap and they didn't replace it with the right motor so I'm kind of concerned now if my pump is shot too. I bought this thing sight unseen from my work from a shop that went out of business and left it behind. I guess we will just have to see. I've got some questions for you all as far as the plumbing and It had some automatic drain thing plumbed into it with a large sight glass. Not something I have ever seen before. Something to do with draining the water out of the tank automatically I assume. I'll post up some pictures as soon as I get a chance and then I'ts time to take the plunge to track down a motor and hope to god the pump isn't toast. Is there a way to run a compression check on a pump like this like in an automobile? thanks
 

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Discussion Starter #14
I dunno it all appears to be in pretty good condition. I pulled the fan cover off tonight and spun it over by hand and everything seems okay. Guess I'll find out when I find a motor. Anyone have a 3HP single phase 1750rpm motor they need to get rid of?
 

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Discussion Starter #15
Baldor motor

Okay guys I need some help as I found a motor on the local CL that fits the HP and RPM /voltage that I need to a T except for it's a general purpose motor with a "C" type NEMA mounting design and it's "footless". Any idea whether or not this will run a compressor pump? Take a peek at the specs and let me know what you think. Welding on a mounting plate is not a problem I just need to know if it will work. This is a nice motor.

Baldor Electric Motor

Here's the specs.

VL3609T Baldor Single Phase C-Face Motor, TEFC, 184TC Frame (3 HP, 1800 RPM)

thanks
 

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Discussion Starter #17
Okay so I finally got around to taking some pics. It looks like this thing comes with an auto-drain thing of sorts. Anyone know anything about that? You can see in the pics theres an threaded opening in the drain valve. Not sure what's supposed to go there. Also looks like 1/4" street 90 they used to come out of the tanks snapped off inside the tanks. That will be fun to get out and replace. I've also got to re-do the copper tubing that's bent and kinked. I've never seen the type of compression fitting they used though. It doesn't look like a standard flare that you would do with an HVAC swedge.







Not sure what goes into this NPT opening here. I didn't un-install this thing.

 

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Don't know about the drain thing, but it's not that hard to crack the drain valve once in a while.
They make pipe "easy outs".
I've also used a cold chisel to remove old threads.
 

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Discussion Starter #19
I figure if I've got the auto-drain there then I may as well use it. I'll figure it out at some point.

Here are the two motors I'm debating on. They pretty much have the same specs but one is Leeson the other is WEG. both farm duty 3 HP 1740 rpm. Weg is shipped for 400 and I think leeson is shipped for 460. Any thoughts on brands vs. price? It appears that the WEG motor has a slightly better efficiency rating.

Leeson Farm Duty Hi-Torque Motor - Model 131542 | QC Supply

New 3 HP Electric Motor 1740 RPM 182T Frame 230 Volt 1 PHASE Free Shipping! | eBay
 
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