They say size matters.... Does it?

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CFM matters on air tools. not sure what your needs/usage is.


I have converted to cordless impacts for working on vehicles.
 
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I have an old SpeedAir I bought at an auction about 15 years ago. It was supplying a machine shop. 80 gallon horizontal tank. 3 cylinder single stage. There's a chart in the owners manual that tells what hp is needed for a desired cfm of air (which is determined by rpm of the compressor). IIRC 3hp will drive the compressor at some rpm(forget how fast) that will put out 18cfm at 175psi. I have it set up for half that. So I have a 1.5hp motor on it and the sheave I'm using runs it at an rpm to put out 9cfm at 175psi. I've replaced a couple valves, filters and gaskets. All parts still available at Graingers. I'm guessing it's 70's vintage. Good old US made machine.

When I bought it, they had been using it for painting, and painting right near the compressor. The oil was filled with grey paint from the overspray. I ran kerosene in it for a few minutes to clean out the crankcase. No problems. Use M1 10w-30.
 
ARB1977 said, "......hopefully I get my father in laws 25 gallon soon."

Doesn't look good for his FIL.

Note to FIL: Watch out for "funny tasting" fruitcake.
 
I think capacity matters depending on what you plan on using the compressor for. I have a small 5 gallon or so compressor that is perfect for airing up lawn equipment tires or for tools that only require shorts bursts of air. It is much easier to lug around than the larger one.

The larger compressor is much better for tools that require large amounts of air to run for longer time periods, such as an air ratchet or die grinder.
 
I have a 15 gallon and a 60 gallon compressor, in all honesty there is no comparison when it comes to air tool use and spraying. Size really does matter.
 
I've got an 18yr/old Harbor Freight ~4gal, 2hp unit (twin tank). It's great for tires and small usage air tools, or where portability is important. I love this little unit because it spins at ~1600rpm and is relatively smooth and quiet.

I also have a ~3yr/old HFT 21gal, 2.5hp unit. It moves a LOT more air, but is heavy, bulky and obnoxiously LOUD given all the cheap oil lubed HFT units spin at something like 3600rpm now. I don't expect awesomeness out of either given the price point, but they work for me. I really only use the bigger one for impact gun use. I think I got the 21gal for $169+ tax with a coupon back then. The little guy was $69 or so 18yrs ago.
 
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I have a 60 gallon single stage horizontal air compressor with a drain lanyard on the bottom like an old semi I can tug on to empty water out of the tank.
 
Originally Posted By: JTK
I've got an 18yr/old Harbor Freight ~4gal, 2hp unit (twin tank). It's great for tires and small usage air tools, or where portability is important. I love this little unit because it spins at ~1600rpm and is relatively smooth and quiet.

I also have a ~3yr/old HFT 21gal, 2.5hp unit. It moves a LOT more air, but is heavy, bulky and obnoxiously LOUD given all the cheap oil lubed HFT units spin at something like 3600rpm now. I don't expect awesomeness out of either given the price point, but they work for me. I really only use the bigger one for impact gun use. I think I got the 21gal for $169+ tax with a coupon back then. The little guy was $69 or so 18yrs ago.


My air compressor is in it's own room so I don't gotta hear it run while I'm in my shop.
 
I used a 60 gallon, 10.2 SCFM Husky Pro (single stage upright head, average hardware store model) until one of the reed valves gave up this summer, but within about a month I moved into my new shop which had an old IR dinosaur with a Model 30 head (V-twin compound, cooler between cylinders, etc.) and 60 gal. tank that still worked, more or less. So I plumbed the Husky Pro inline with the Ingersoll and just used it as an extra tank, but the old compressor struggles to keep up with any extended use of a die grinder, etc. so I got ahold of an Ingersoll head that'll fit the Husky (buddy has the scrap contract for the IR factory in town) and just got it bolted on last night. Gotta get a belt for it and then I'll have 120 gal. of air and at least 18 CFM judging by the dinosaur's output compared to the Husky's.

With that combo I'll stage the old compressor to kick in second to keep it in one piece longer, and shouldn't have to worry about letting up at all with a die grinder, DA sander, etc.
 
3 hp 50 gal
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I have an 8 gallon Kobalt. I now use it for tires and the odd ugga-dugga here and there.

I bought it when I was doing sheet metal stuff on the side and it did alright. It wouldn't run the hammer while it was filling but it's not a long wait.
 
Well I've never measured my CFM but I'm sure it's much smaller than most guys have....
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