Air Compressors

[Mike Switzer]

In 1993 I bought the biggest air compressor Craftsman sold, a 5hp 30 gallon single stage. At the time it was the biggest single phase 220 volt compressor you could buy. The tank has developed a pinhole leak & a replacement is no longer available. I was going to buy a 60 or 80 gallon tank for it, then I saw how much that would cost & I started looking at 80 gallon 2 stage compressors. I was considering the Kobalt that Lowes sells for $950 (made by Campbell Hausfeld) then I discovered the pump life rating is only 10,000 hours. Looking at the automotive & shop equipment suppliers there seems to be a wide range of brands (and varying reviews on quality) in the $1000 - $1700 range.

For those of you that have 2 stage compressors in your shops what brands seem to work good & which ones should I steer clear of? Thanks.

[CraigCantwell]

Mike: 40 hours a week, 52 weeks a year for just under 5 years to get to 10,000 hours..... If you want a real workhorse, 2 stage, then the commercial level IR, Quincy and Champion are the brands to go with. I've got an IR T-30 that was built in '62 that is about to come out of storage, and I can still get parts for it if needed.

One option for you is to buy a dead compressor off of Craigslist and remount your power unit to it.

You can also find used 3 phase units fairly cheap at times too, but changing over to a single phase motor is going to be several hundred bucks. If you choose this route, make sure you buy noting bigger than a 7.5 hp unit, or replacement motor and shop wiring are going to eat you alive.

[martymayes]

I have a similar air compressor from the 1970's that developed a leaky tank. Still looking for a tank because the compressor is otherwise still going strong. My 20 y/o C/H upright probably has ~7-8000 hrs and it's giving me trouble. The new "sealed" motor/compressor rigs are annoying loud.

Don't run away from an industrial compressor with a three phase motor. Just install a VFD and you can do some neat stuff with it.

[Mike Switzer]

I went to the local Rural King store today & was looking around (they had a clearance sale & some new guns), They have a 80 gallon Dewalt compressor for $999, more CFM than the Kobalt. Turns out it is made by MAT Industries in Long Grove, IL. The same compressor is sold under a 1/2 dozen different names, including Sanborn. (The painted over ASME tag on the tank says Sanborn on it). Can't find any info on pump life rating though. TP tools has some nice Champions (made by Gardner Denver) but they are a bit more $$.

I have been looking at Craig's List & local ebay listings but haven't found anything yet that I am interested in. I sure don't want to buy a used tank that may also spring a leak & possibly turn into a bomb.

[CraigCantwell]

[QUOTE=martymayes;74897
Don't run away from an industrial compressor with a three phase motor. Just install a VFD and you can do some neat stuff with it.[/QUOTE]

Where you have to be careful about the VFD is sizing and having the available power to run it. Most VFD manufacturers tell you that for compressor usage, the drive needs to be rated to handle 2 to 2.5 times the nameplate hp of the compressor motor. For example. a Spedestar PC1-100 is rated for a 7.5 hp motor, but it pulls 72 amps when running that motor. To hang one in the shop is over a grand, and you would most likely have to add in the cost for an electric unloader so that you could program it to soft start the compress and not exceed the current limitations.

I had been looking at going the VFD route with my big compressor, but decided to drop less than half the cash and swap it over to a single phase motor and only need a 40 amp circuit.

[dclaxon]

In about 1959 or '61, (don't remember the exact year, but I was in 2nd or 3rd grade, and I graduated H.S. on '70.) my Dad bought a reman Quincy, 2 stage, 60 or 80 gal, 5 hp, and it was still running when the motor burned up a couple of years ago. Unfortunately it is still sitting there waiting for a new motor, because 5 hp single phase motors don't come cheap, and as long as my 1 hp 30 gal compressor is keeping up with about 90% of what I ask of it, it is difficult to justify the expense,
Dave

[vaflier]

In about 1959 or '61, (don't remember the exact year, but I was in 2nd or 3rd grade, and I graduated H.S. on '70.) my Dad bought a reman Quincy, 2 stage, 60 or 80 gal, 5 hp, and it was still running when the motor burned up a couple of years ago. Unfortunately it is still sitting there waiting for a new motor, because 5 hp single phase motors don't come cheap, and as long as my 1 hp 30 gal compressor is keeping up with about 90% of what I ask of it, it is difficult to justify the expense,
Dave
You can probably have the motor rewound for way less than the cost of a new one.

[Mike Switzer]

You can probably have the motor rewound for way less than the cost of a new one.

Yea, we did this all the time when I was a maintenance engineer. Way cheaper than buying a new one. Most places that sell electric motors for industrial use can rewind them (or send them out to be done).

[FlyingRon]

For what it's worth, I've found Tractor Supply to be the best place for compressors and other air related things around here.

[Mike Switzer]

One thing I have figured out, I am probably going to have to do some electrical work if I upgrade. I currently have a 220V 30 amp breaker feeding 10 ga stranded wire running approx 70 feet in EMT. The current 5 HP motor says it pulls 13.8 amps. Anything I am looking at pulls between 22 - 28 amps for a 5 HP compressor. I figure I will split the 2 hot wires I have now to make 2 30 amp 110 circuits & have to put in a new 220 circuit with 6 or 8 ga wire on a 40 or 50 amp breaker if I upgrade. Wouldn't be a big deal except my shop is so full of crap & unfinished projects I will have to empty it out to run a new circuit. I have a bad knee I don't like ladders.

[BJC]

...I currently have a 220V ... 5 HP motor says it pulls 13.8 amps.

I am looking at pulls between 22 - 28 amps for a 5 HP compressor..If those are full load amps, it is too big a difference to be based on motor efficiency. Almost looks like a three phase verses a single phase motor.


BJC

[CraigCantwell]

If those are full load amps, it is too big a difference to be based on motor efficiency. Almost looks like a three phase verses a single phase motor.


BJC


The 13 amp one sounds like some of those "Magical Mystery Motors" from years ago that claimed horsepower ratings greater than known electrical norms... Like the shop vacs getting 6 hp from a 110/20 amp circuit....

[FlyingRon]

Note, you can not put 15 or 20A recetpacles on this repurposed circuit unless you also drop the breaker down to 20A. Also note that if this is a garage or an accessory structure at or below grade 110 15 or 20A receaptcles require GFCI protection. If you want to use this MWBC (i.e.,shared neutral) you're going to have to be careful how you do your GFCI protection. Either use a 2 pole (with load neutral) GFCI in the panel or GFCI receptacles at each point where the neutral is still shared (you can't have one neutral connected to the protected side of multiple GFCIs.).

[dclaxon]

You can probably have the motor rewound for way less than the cost of a new one.

I tried that already, the shop said it was too toasted to repair. The problem was that they could also not get me another motor like it any more, it was a 5 hp motor built on the frame for a 7.5 hp. The options were to get a 5 hp on a different frame, and change the mounts and the pulley, or get a 7.5 on the same frame. But I don't think the electric service to the property would handle the bigger motor, the whole house would dim momentarily whenever the old one kicked in. And as I recall, when Dad bought it back in the day, he had to have the service upgraded to the airport where his shop was.
Dave

[Mike Switzer]

The 13 amp one sounds like some of those "Magical Mystery Motors" from years ago that claimed horsepower ratings greater than known electrical norms... Like the shop vacs getting 6 hp from a 110/20 amp circuit....

Could be. It is a GE motor & on the GE motor sticker where the HP is supposed to be listed it is blank.

I do remember however when I bought it the instructions called for a dedicated 30 amp circuit.

[CraigCantwell]

Mike: What's the frame number, shaft size and RPM? Changing over might not be as bad as you think.

[Jerry Jackson]

You can probably have the motor rewound for way less than the cost of a new one.

Get quotes from some re-wind companies, you might get lucky. I got a re-wind quote that was higher than the cost of a new motor from Leeson. Air comressors put a heavy start-up load on motors and cheap motors may not survive that duty.

Jerry

[Mike Switzer]

Does anyone have any recent experience with Quincy? Specifically do they honor their warranty? I was looking at this 60 gallon compressor available at several places for $1299, specs are as good as many 80 gallon units, it is advertised as 50,000 hour pump life. I was going to pull the trigger on it then I found several very negative reviews regarding the warranty & customer service, & I discovered that to get the extended warranty you need to spend another $150 on the extended warranty kit (basically several quarts of oil & some filters).
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