Shop Compressors

Let'sgoflying!

Let'sgoflying!

Touchdown! Greaser!
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Dave Taylor
I need one for my garage (no airplanes involved).
Tires, blowing stuff clean, filling a portable tank. No air tools planned. May take on some riveting later.

a) What volume will work best. Don't want p falling off when using it on a big job. But if its empty(I might leave it off), don't want to wait for a month while a big tank fills.

b) Is a 120v job going to work? Last?

I am thinking 30gal, 120psi, 240V right now.

Any brand prefs?
Any features I should look for?
 
My cheap ass 110 V Sears compressor is about 20 years old. Works fine but it's noisy. Real noisy. But it works. It's an oilless compressors so it is noisy. Really noisy. The covers have fallen off the gauges. It makes a lot of noise, but it compresses air. And makes a lot of noise.
 
My old shop compressor is a double pump 20 gal, 230vac.. Its actually a Cambell Vanhausfield.
 
Sears compressors, among others, overstate the horsepower ratings. They'll say, for instance (and I'm making up some numbers here) that it has a 3-hp motor, but it only draws 10 amps at 110VAC. That's impossible. 10 amps times 110 volts is 1100 watts; divide that by the 746 watts per horse and we get much less than 2 hp.

Direct-drive oilless compressors sure do make a lot of noise. A proper belt-driven, oil-sump unit is quieter and will last a lot longer. Not so important at my age, maybe:)

Dan
 
I traded a Sears 3hp 20 gallon tank oiless for my smaller oiled (carry by hand) compressor (To my Dad.... he got the better deal). I miss the small one for filling tires and blowing stuff off.

The big one is never full when I want it. Noisy as crap. I mean..... really noisy. And it doesn't keep up with the bigger air tools anyways.

Id recommend a small oil-filled unit. If you want to go big..... go as big as you can afford. (Large motor and two stage compressor, oiled, belt driven, 80gal tank).
 
I have a 26 gallon unit that fills to about 135 psi. It was roughly $250 and does what I need just fine (fill tires, impact wrench some, air ratchet some).
 
Let'sgoflying! said:
so no issues with the lower voltage ones?
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No. I may have the same 20 gallon "5 hp" Sears compressor as another poster. Loud, but worked well through the building and painting of my RV plus a thousand other projects.

They have re-rated compressors since I purchased that one. The old 5 hp rating was based on inrush amperage when the motor started. A bogus metric. Today, that compressor would be rated at ~1.5 hp, based on motor efficiency and running amperage.

If your max planned activity is riveting, you don't need a particularly big tank or high hp motor. A 10 gallon tank and 1 hp motor would probably be fine. Drilling, grinding, and painting are activities which typically require much more air than riveting.
 
kyleb said:
They have re-rated compressors since I purchased that one. The old 5 hp rating was based on inrush amperage when the motor started. A bogus metric. Today, that compressor would be rated at ~1.5 hp, based on motor efficiency and running amperage.
Click to expand...

About time. I figured they must have be cheating somehow.

Dan
 
Dan Thomas said:
About time. I figured they must have be cheating somehow.

Dan
Click to expand...
There's an old industry standard for electric motor horsepower rating that basically gives the maximum HP the motor can deliver (briefly). They start with the motor unloaded and gradually apply increasing torque resistance while measuring the torque and RPM. Then they graph the product of torque and RPM to find the peak HP. Never mind that the motor will overheat and burn out if it's called on to deliver that much HP for more than a few seconds or that the motor current will greatly exceed the nameplate ratings.
 
At my previous home, the prior owner had the compressor set up downstairs in the furnace room with a relay-switched 3-phase outlet next to the main panel. It was plumbed into the garage with a hose-reel and some taps over the workbench. If you needed air, you could switch it on with a green/red pushbutton box at the workbench. Sadly the industrial compressor was an exclusion in the purchase contract.
 
Let'sgoflying! said:
I need one for my garage (no airplanes involved).
Tires, blowing stuff clean, filling a portable tank. No air tools planned. May take on some riveting later.

a) What volume will work best. Don't want p falling off when using it on a big job. But if its empty(I might leave it off), don't want to wait for a month while a big tank fills.

b) Is a 120v job going to work? Last?

I am thinking 30gal, 120psi, 240V right now.

Any brand prefs?
Any features I should look for?
Click to expand...


For what you're talking about, any Sears, Lowes or Home Depot compressor will do. You could get one of those air compressor/ jump box combos and keep it in the car even.

Now, when it comes time to run that river gun and other tools, then you'll need more and you get a Quincy.
 
I got a cheap Harbor Freight thing that uses oil and was far less than $250 for little stuff like tires and blowing stuff around in the garage.

It's been fine. Has a ten gallon tank I think. Bought a cheap not-very-flexible hose with it and that thing's a pain. Will probably upgrade that to a wall-mount reel with a real hose.

Little too heavy to drag to the hangar though.

A high-volume bicycle pump works well for the airplane tires and gives a minor workout in the process. ;)
 
Usually it's volume, not pressure that gets in the way of a given project. You can add volume temporarily to a smaller unit with a couple of portable pressure tanks, t - fittings, quick connects and some extra hose.

I have a 10 gal 5hp 120v that I stretch to fit occasionally.
 
Chip Sylverne said:
Usually it's volume, not pressure that gets in the way of a given project. You can add volume temporarily to a smaller unit with a couple of portable pressure tanks, t - fittings, quick connects and some extra hose.

I have a 10 gal 5hp 120v that I stretch to fit occasionally.
Click to expand...

Wouldn't it be cheaper just to buy a compressor with 5 extra gallons
 
Tom-D said:
I bought one of these http://www.grizzly.com/outlet/1-Gallon-Pancake-Compressor/H7360 to carry to annuals to pump up tire, struts, and clean plugs.. works great.
Click to expand...

I had one similar to it (probably same compressor unit, dual tanks on the side) that was $89 at the car parts store. Worked well for about 5 years of occasional use with pneumatic scissors, drill, impact gun etc. until it started 'making metal' and eventually seized. So, my compressor cost was $17.80 per year, an sum I can live with.
 
I have a large upright 240VAC compressor in my garage. I think it's a real 5HP which is near the upper limit for typical single phase motors - with honest ratings. I have it plumbed to a couple of spots along one wall and to a retractable reel on the ceiling in the middle of the garage. One of the takeoff's has an oiler so I don't have to put oil in my air tools. If you're doing any painting or sand blasting, get an electric air dryer with a compressor. I can't remember the brand but the case is blue. What a difference that things makes. At my hanger, I have a small porter-cable pancake compressor that is okay for tires and stuff.


edit - the air dryer is a Hankinson - not cheap but much better than a simple water trap.
 
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I'm looking for one also. I have a portable oil less type. I need the air to be clean and I had to clean the spray gun part at the end of the line to get all oil residue out of it. After that, it has provided clean air (other than moisture) since. I'm considering a 2 stage, oiled type for a shop like the OP. But, I am wondering from those who have used them, can they provide clean air also, or does the oil leak through to the output hose?
 
skidoo said:
I'm looking for one also. I have a portable oil less type. I need the air to be clean and I had to clean the spray gun part at the end of the line to get all oil residue out of it. After that, it has provided clean air (other than moisture) since. I'm considering a 2 stage, oiled type for a shop like the OP. But, I am wondering from those who have used them, can they provide clean air also, or does the oil leak through to the output hose?
Click to expand...


always use a filter on the out put line, a water trap is also a good idea.

I flood my shop compressor with WD 40 once per year, and then drain the tank and allow to set over night with the tank drain open.

you'd be surprised at how much stuff comes out.

Yes I pour about a pint of WD 40 into the intake ports of the pump while it is running. it cleans the inlet check valves and lubes the pistons and cleans the outlet check valves.
 
dell30rb said:
Wouldn't it be cheaper just to buy a compressor with 5 extra gallons
Click to expand...

Not if you already have a 5gal tank for portable use, and can fab a t-fitting in about 5 minutes.

I did the same thing a few years ago to blow out the sprinklers. The existing tank was just a bit short of volume, and there's no sense buying a new compressor for a once-a-year, 15 minute job.
 
weilke said:
I had one similar to it (probably same compressor unit, dual tanks on the side) that was $89 at the car parts store.
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Yep. I got mine (Porter Cable) at Home Depot during a rocking sale, it was part of a bundle with a finish nailer and framing nailer that I was going to buy anyway. The difference between the cheapie unit and buying the guns separate vs. the bundle was less than $100, so it was an easy choice.

But for occasional use (which is what 99% of us actually use them for), the cheapie units are just fine, and it's hard to justify paying 2-3x the price.
 
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I am wondering from those who have used them, can they provide clean air also, or does the oil leak through to the output hose?
Click to expand...

I have never noticed any oil residue on any tools or fittings on the oiled compressor at the hangar, and I have done touch-up jobs with no problem. I wouldn't try to paint a whole airplane with one, probably buy a dedicated unit (Croix) for that.

I wonder if this wouldn't also be a good idea.
 
PilotAlan said:
Yep. I got mine (Porter Cable) at Home Depot during a rocking sale, it was part of a bundle with a finish nailer and framing nailer that I was going to buy anyway. The difference between the cheapie unit and buying the guns separate vs. the bundle was less than $100, so it was an easy choice.

But for occasional use (which is what 99% of us actually use them for), the cheapie units are just fine, and it's hard to justify paying 2-3x the price.
Click to expand...

Same thing I did. Needed the nailers for the shed I was (am) building. I've got a Costco cheapie out at the hangar for filling aircraft tires.
 
Dan Thomas said:
Sears compressors, among others, overstate the horsepower ratings.
Click to expand...

Sears (or shop vac) HP does not equal real HP - so that number is totally irrelevent when comparing compressors. Though I see that they are now using some more realistic numbers at least for this one:
http://www.sears.com/shc/s/p_10153_12605_00916473000P?prdNo=4&blockNo=4&blockType=G4
Which is close to what I have.

The "xxx" PSI number is pretty much irrelevent as well.

Flow at psi is the thing to compare (and hope is reaonably accurate).
(example 5 SCFM at 90 PSI)

It sucks to not have enough to do what you want to do on a reguar basis, but there is not much point in buying more.

If you want to sand blast - a 110 volt compressor will not keep up. You have to blast / wait. Blast / wait. A big tank helps, but the wait is longer. That works for me because I do it so infrequently.

Spray - purd near anything will work.

Filling tires - small tank, anything will work.

Riveting - a good 110 V compressor is fine

Air grinders - check the ratings

etc.

Define you mission. :rofl:
 
My small compressor keeps up with my rivet gun OK, it will run quite often.

any airmotor tools such as a die grinder, and sand blasters will require a large amount of air, bigger compressors are required.
 
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Capt. Geoffrey Thorpe said:
Sears (or shop vac) HP does not equal real HP - so that number is totally irrelevent when comparing compressors. Though I see that they are now using some more realistic numbers at least for this one:
http://www.sears.com/shc/s/p_10153_12605_00916473000P?prdNo=4&blockNo=4&blockType=G4
Which is close to what I have.

The "xxx" PSI number is pretty much irrelevent as well.

Flow at psi is the thing to compare (and hope is reaonably accurate).
(example 5 SCFM at 90 PSI)

It sucks to not have enough to do what you want to do on a reguar basis, but there is not much point in buying more.

If you want to sand blast - a 110 volt compressor will not keep up. You have to blast / wait. Blast / wait. A big tank helps, but the wait is longer. That works for me because I do it so infrequently.

Spray - purd near anything will work.

Filling tires - small tank, anything will work.

Riveting - a good 110 V compressor is fine

Air grinders - check the ratings

etc.

Define you mission. :rofl:
Click to expand...

Finally. Someone who mentions what's important.

FLOW. In CFM. If you aren't running power tools then anything will work, even the cheap 2 and 3 gallon compressors with low flows.

If you run any sort of turbine tools then CFM is what matters. Look at what the tool needs. Look at what the compressor gives. If the flow is less than required by the tool that's where big tanks come in handy.

There is no practical reason for a 240v compressor in a home shop that's not using lots of high flow tools like drills, cutters and impact wrenches. Unless you just want it.
 
skidoo said:
I'm looking for one also. I have a portable oil less type. I need the air to be clean and I had to clean the spray gun part at the end of the line to get all oil residue out of it. After that, it has provided clean air (other than moisture) since. I'm considering a 2 stage, oiled type for a shop like the OP. But, I am wondering from those who have used them, can they provide clean air also, or does the oil leak through to the output hose?
Click to expand...


There are inline products that will clean the air to whatever specification you need. A good quality regular piston compressor can certainly be used. If you need really clean air, check out the filtration systems for SCUBA fill stations. The place where I worked when I was 12 (1977) was a car dealership with a busy shop, and at that time they bought a new Quincy 5 hp, IIRC 3 stage compressor. That compressor has been in continuous shop service since and was still functioning when I saw it on my way to OSH.
 
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Doggtyred said:
There is no practical reason for a 240v compressor in a home shop that's not using lots of high flow tools like drills, cutters and impact wrenches. Unless you just want it.
Click to expand...

The most pertinent post on a board full of aircraft owners.
 
PilotAlan said:
.
.... the bundle was less than $100, so it was an easy choice.

But for occasional use (which is what 99% of us actually use them for), the cheapie units are just fine, and it's hard to justify paying 2-3x the price.
Click to expand...

I was happy with it while it lasted, I just wanted to point out that you get what you pay for.

The fast-running 'cheap sheet from china' compressor simply wont do this:

Henning said:
That compressor has been in continuous shop service since and was still functioning when I saw it on my way to OSH.
Click to expand...

The older I get, the more I appreciate well made tools. Just a couple of weeks ago my cheap 'craftsman' 3amp drill gave up the ghost. Back to swiss made equipment on that front.
 
weilke said:
The older I get, the more I appreciate well made tools. Just a couple of weeks ago my cheap 'craftsman' 3amp drill gave up the ghost. Back to swiss made equipment on that front.
Click to expand...

Quincys are pressure oiled as well.
 
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