Picking an Air Compressor

[Moses Ludel]

Choosing an air compressor is not a light subject.  This can be an expensive purchase, and an unwise choice is costly and frustrating.  This is not an item for "cutting corners" or bargain shopping.  You will get what you pay for...

 

When I needed an air compressor for the magazine's shop/studio, my thoughts were about air tool operation.  My previous shop was well served by a DeVilbiss 80 gallon upright compressor and a quality black pipe system.  That compressor was a two-stage (not "twin stage", avoid these!) iron compressor model that ran on 230V.  Bought it in 1995-96 timeframe from Costco for $800.

 

Our new, smaller scale shop/studio, I thought, could get by with a 20-gallon upright portable compressor and an iron, two-cylinder unit compressor head (two-stage, of course).  The Ingersoll-Rand 'Garage Mate' fit the specifications I wanted, and that purchase proved wise—initially.

 

There are jobs that require high volumes of air, and one in particular is bead blasting.  The smaller compressors, you will discover, often make higher output ratings by running the compressor's rpm up the scale, to the point that service life becomes an issue. 

 

The DeVilbiss unit, in fairness, held up in this category with its 7.5 HP motor.  (The I-R Garage Mate gets used so little that it should also last "forever".)  Horror stories about sucking a reed valve on the DeVilbiss never happened, and that unit served faithfully for fourteen years—it was still working fine when we sold the shop property and the complete air system stayed at the shop. 

 

When I discovered the need for another bead blaster (had one at the previous shop, a very nice T-P Equipment unit), I thought a smaller unit would work fine with the Garage Mate compressor.  It didn't.  After much research and study, I realized that volume is everything for blasters, and my quest turned up a terrific solution: a used commercial compressor with a huge, slow speed Champion R-15 compressor head, 120 gallon horizontal tank, and a 5-horsepower, industrial strength Baldor 220V motor with magnetic starter.   

 

If you'd like to know more about this compressor, and perhaps what amounts to my sense of humor, read this account at the magazine: http://www.4wdmechanix.com/Downsizing-and-Air-Compressors!.html.  For $250 less than the new I-R Garage Mate cost, I'm in business and so is the bead blaster! 

 

There are values like this around if you'll look and be patient.  The Garage Mate works fine for quick, shorter burst air tool chores or inflating tires.  I'll keep it, as the resale price is ridiculously low, and the unit is in "as new" condition.

 

Moses

[BadDriver4x4]

I hear you about compressors. I still have a hard time making up my mind whether I can compromise or if I should go whole hog and get the best I can find at an auction or estate sale. Craig's List can be a real headache with some things. Just missed a large "kitchen" exhaust hood and fan that would have been great over my welding table as a way of keeping fumes down in the basement. (Free too)

What do you think of soda blasting, and what compressor would be best to do the job of outdoor paint and rust stripping from sheet metal? A small blasting cabinet as well?

What I have now will power a bicycle tire fill and a small gauge brad nailer. 

I've done my homework over the years, but all of the CFMs and PSIs and Stages are blurred together at this point. I now have an electric air wrench that I bought at Sears with 350 ft lbs torque, electric 1 - 4 " and 3 - 4 1/2" grinders, and a never used Dewalt 7 1//2" dual action sander/buffer and I'm soon to have electric sheet metal shears. While my air grinder, wrench, cut off tool and other goodies gather dust waiting for a good compressor to bring them to life.

By the way the name's Allen (Haven't used it yet. Don't know why.)

Edited February 21, 2016 by BadDriver4x4

[Moses Ludel]

Allen, Happy New Year!...Soda blasting is great for pot metal castings like carburetors.  You've likely been through the TP Tools catalog, most of us have...I've owned two TP blasting cabinets, the first one commercial grade with enough width for a Jeep axle housing (without brake parts attached).  Their products are good, and soda blasting or dual-mode equipment is available.

The real issue is the compressor volume and pressure.   You need a tremendous amount of both to run any blasting cabinet.  I invested in a new I-R Garage Mate, thinking I didn't need a big compressor any longer, it works okay for light air tools and tire inflation.  It was completely inadequate for the TPI 360 cabinet I now have in my downsized shop/studio.  I got very lucky finding an industrial strength compressor from a body shop that was on its way out of business.  The unit had been used with water filters and drained automatically.  It has a 120 gallon horizontal tank and huge Champion compressor.  Even with plenty of reserve air capacity, great sealing and big piston displacement, the unit still comes on plenty when I'm bead blasting!  You need volume and pressure for high output air tools as well...

I've had an 80-gallon upright two-stage compressor ($800 DeVilbiss) with iron lined cylinders (two) that was okay for basic shop use, including most tools and the blasting cabinet.  Avoid, however, "twin-stage" compressors, make sure the cylinder is iron and two-stage design.  I'd hold out for a commercial grade compressor like mine, just make sure it's in good condition if you buy used...Rust, scale, worn piston rings and bad bearings or a damaged crankshaft are some areas to consider...

Moses

Edited January 4, 2016 by Moses Ludel