Piecing together a 7.5HP 2-stage compressor

Schroeder

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Has anyone ever done this? Brand new compressors (tank, motor, and pump) fully assembled seem to cost $2k-$3k online. Those are the Quincy prices on eBay anyway. I have a 60gal tank and single stage compressor set up already. Would it be wise of me to buy a 7.5HP motor for $500 ( https://www.ebay.com/itm/271956786548 ) and a cast iron 2-stage compressor for $600 ( https://www.ebay.com/itm/391668039922 ) and just mount them on the tank I already have? In some previous posts you guys said my compressor wasn't big enough. This route would only cost me $1100. I realize I may have some more money in the retro fit, but it shouldn't go over $200. This route could save me $700-$1500 I figure

I'm not a shop. I'm doing 1 car. I may do another one in the future, but this is a rare occurance and only a hobby. I am a farmer though, and my compressor does fall behind with the regular use of air tools. It may be time for an upgrade anyway.
 
anything using a 3450 rpm motor is junk. IR is a good example . buy a compressor that runs slower. my old one used 1750 motor and ran at 850 rpm. the new ir i bought runs high rpm and makes a ton of moisture not to mention it will like only live a few years .
 
Here was another idea presented to me. I have 2 shops both with a 5hp single stage compressor on a 60 gal tank. What if I pulled the 1 from the shop I won't be painting in, brought it to my paint shop, and hooked it to my other compressor tank!? 2 single stage 5hp compressor setups on a total of 120 gallons of air.
 
i have only a 5 hp in my shop. my old champion was far better than the ir . if you have a true 5 hp then it is all you need. a 5 hp electric motor is heavy as hell and will have a lifting loop on it . the pulley is a 7 in .
 

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Thanks for the reply. I'll go look at my compressor and see if it's truly 5hp. I doubt it, so back to the question of hooking 2 compressors and tanks together. Wouldn't that be beneficial?
 
I've been happy with my compressor that I purchased from Eaton about 5 years ago. It was reasonably priced and seems to be very durable.
 
find a compressor shop and see if they have a champion rebuilt. avoid the Chinese built compressors. most are over rated and run at high speed to make u for it. like the pos ingersal rand i bought . has to run twice as fast as a champion and delivers less cfm and more heat.
 
See if you can find a deal on one of these..
http://www.ebay.com/itm/Ingersoll-Rand-T30-air-compressor-with-Baldor-Industrial-Motor-/182740449624
I have a 5hp 80 gallon version

Shine is ripping on the IR, but I am guessing he is talking about the new, beige Chinese ones. The old grey ones are work horses...
I got mine off Craigslist and paid 700 or 1200.. cant remember. But it is content to run all day if it has to. Only problems I ever have with it is in the motor theres some flyweights that go to a clock spring as from what gather is part of the start cap wiring. Once every few years I need to take the motor cover off and clean them up.

Water on mine isnt a problem unless I have been doing A LOT of constant duty stuff. Like if I am media blasting something big, then working through the 2K and filler stages with the sanders, after a few weeks the lines will start spitting water. I drain my drops and drain the tank and good for another several weeks-months. FWIW, my compressor sits outside and 75-100% humidity is common here.
 
i bought a new ir 5 hp pump to replace my old champion. the ir is junk and like everything else it is Chinese . having my champion rebuilt . getting an older rebuild is better imo .
 
Getting a 7.5hp motor and pump unless you know what you are doing is stupid. Do you know what to look for in a motor? how about a pump? do you even know how to set-up the pulley's properly so you don't over/under drive things? Why look for a 7.5? unless you look for the proper pump to get the most out of it you are wasting your time and money. The CFM gains on a standard 7.5hp set-up is not much more then a 5hp except they spin the pump faster (but I'm sure you did your home work on that). There are units out there that you will see a benefit from getting a 7.5hp one example is the Champion but you have to look at the one that uses the 10hp pump not the 5hp pump.
 
Thanks for the reply. I'll go look at my compressor and see if it's truly 5hp. I doubt it, so back to the question of hooking 2 compressors and tanks together. Wouldn't that be beneficial?

You clearly don't know what you are doing and hooking 2 together is like making your own Duplex unit, I use a Champion 10hp ("R" series) Duplex (twin 10hp setups) on a 250gal tank daily. To make that work you will need to make one a "lead" pump and one a "lag" pump so they both don't fire up at the same time. You will have to set up a switcher box so each one alternates during the run cycles and if and when the demand requires will let the other fire up to keep up with the CFM demand. If you even think of firing both at the same time I promises you will fry your breaker box, the demand will exceed 80 surge amps every time. You want to do that buy a Duplex unit it is plug and play. The tank sizes are what they are so you get the most out of the motor/pump's life and keeps the run time where it needs to be without unnecessarily warring the pump out.

I highly recommend you get a Champion "R" series compressor and forget what you are thinking, that is a hacks way of doing it. There is no way you will ever kill it they are bullet proof and made in USA. You want to play you need to pay, buy once cry once.
 
Another vote for Champion! I would also look for Saylor Beall 705, older Quincy 325, or Kellogg American. However, the Champion is the easiest and cheapest to work on and repair.
 
Heres my work in progress. The blue tank is the only remaining piece of my Eaton 10hp POS. I paid 300 for the lower 7.5hp Quincy that had been tipped over and the electrical motor broken. I repaired the motor and rebuilt the 340 pump. Probably have 600 into it. The blue 325 pump is a craiglist special. I paid 400 for the pump on a 30 gallon tank. Was a backup from a drycleaners that had never been ran. Picked up the antique motor from craiglist also. It's between 3-5 hp but it's superior to the new stuff. Enough windings in it to wrap around the planet. Lots of pulley calculators on the net. I clocked the output of the old motor with a handheld tach. Dialed the compresser speed to 450 rpm's. It's quite and doesn't make much heat. I use the small one daily and turn them both on to run my big pressurized blast cabinet.

50 bucks for the electric air dryer from craiglist. Not refridgerated but it doesn't need to as it's way oversized. I did buy a new Sullair coalescing filter (green thing) and into a desicant tower I scored from my old job. Water isn't ever a problem for me.

Lots of good deals for old Saylor bealls, Quincy, Kellogg American, IR. Parts available and easy to rebuild.

The framework is coated in SPI epoxy. Sorry, had to insert an SPI plug.
 

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If your dead set on a 7.5hp then hell yes, that is the one you want, no if's, and's or but's that unit is a bad ass. That unit has a V pump which is 2-5hp (the same one that comes on the 10hp compressor) pumps set in a V and the RPM's are turned down to run slower then a 5hp but gives way more CFM. I believe the pic shows it with a factory installed after cooler but the description does not mention it but it is worth having it even if you have a ref. air dryer.

Just have to make sure your electric can handle the load.
 
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The other 7.5hp they make comes with the 5hp pump, it's just sped up a little to give more CFM (not much more) and is geared to the people that just have to say theirs is 7.5hp, purely marketing but will still out last any other 7.5hp out there you just don't gain a hole lot more CFM compared to the big boy 7.5hp.
 
That champion is too much money for me when I’ll only need this for one or two cars. I want to make what I have work. Even if that means having to do a couple extra steps or something to allow the compressor to keep up.

DATEC, you said I don’t know what I’m doing. You’re right. I don’t. If I did I wouldn’t be here. You asked do I know what I’m looking for in a compressor and pump. No I don’t. That’s why I started this thread. There are many threads like this. I’ve searched and read. Everyone is always in their own little situation though with its own circumstances.
 
Schroeder, sometimes just because you want to do something doesn't necessarily mean it can or should be done. Datec is harsh because he is trying to get it into your head that not knowing what you are doing and trying to cobble together pieces and make a air compressor can kill you or anyone else who happens to be around. What if that is your kid or your wife? If your intention is only a car or two, then go with something like the IR 5hp 2 stage. It'll have plenty of air for what you need it for. It's relatively affordable and when you get done doing what you are doing, sell it on Craigslist for at least half maybe more of what you paid for it. If you need a compressor for occasional farm use it would work well. They are actually made in India not China and for the most part hold up well. I know of one that a guy bought in 2001 (Indian made) and it lasted 12 years of heavy use and abuse. Intake filter rarely got changed and neither did the oil. When it quit pump was still good the motor finally quit.
 
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