Air Compressor Advice - Big or Small?

[zoinksjaguar]

Looking for any recommendations on a small, economical ($200 or less) air compressor to run a 3/8" impact ratchet for an upcoming brake job (need to replace front & rear brake pads & rotors) to loosen a few 14/19 mm bolts torqued to approx 75-80 ft-lbs. Have had problems in the past with rusted bolts that took **forever** to loosen (even after applying lots of penetrating oil) and I'm trying to work smarter, and not harder, in my old age

Can I get away with a small "pancake" type compressor that only has a 4-5 gallon tank and that's rated at 3 cfm @ 90 psi? Or will I need a larger compressor? The smaller "pancake" compressors seem geared towards running a nail gun. Not sure if these can also be used for running an impact ratchet for some small jobs.

Thanks in advance for any feedback!

 

[another Todd]

They will run an impact for very short bursts. You would be better off IMO with a compressor that has more CFM and a larger tank---say 20 gallon. Personally I do not like the oiless compressors as the ones I have seen vibrate all over the garage. But if $200 is your limit, you may not have much of a choice.

 

[Craig in Canada]

Oil-less isn't what makes it vibrate all over, it's whether it's single-stage direct drive or not. I have a cast iron, oiled single stage 8gal that is probably what you're talking about. In my case I got the compressor and a bunch of (cheap) tools, hose, fittings for $200CDN and a bit. A belt-driven, quieter compressor is over $500CDN with nothing but a power cord, by comparison.

I would certainly not get a pancake type, and if you're trying to stay around $200 and buy new I think you'll probably find that direct-drive is the only thing in that range. C-H makes a couple of direct drive units that are still an oiled type. I would whole-heartedly agree with that recommendation for longevity.

 

[Dave H]

I would suggest you get the biggest, most cfm you can afford. My 4 gal, 2.5 hp, 5.XX cfm/90 psi barely runs my 1/2" impact wrench when using a standard 1/4" hose (my 3/8" hose works better with it, but is a chore dragging out because it's 40' long). I would most likely be better off with a 3/8" impact wrench, and a shorter 3/8" hose. Even a 3/8" air ratchet on mine will only run in short bursts.
When I get the chance to replace my air setup, a bigger, much more powerful compressor is at the top of my list. The twin tank or pancake types are good for general stuff around the house (brad nailers, air brushes, inflate tires, etc...). But they (atleast mine) lacks when it comes down to automotive work and stuck fasteners. I usually end up using a breaker bar and cheater pipe for really stuck stuff, which defeats the purpose of my getting a compressor and impact wrench.

Dave

 

[i_r_teh_noobz]

My impact is almost useless for stuck bolts. I find that the gigantic wrench of doom works much better - especially when combined with the BFH.

 

[Craig in Canada]

DaveH: I think you just need bigger tanks. 5.xx scfm@90psi isn't all that bad, but 4gal is a little small. For a lot less money would could try putting an extra air tank in that setup to run the 1/2" impact for longer bursts.

When taking off tires, I find that my 8gal 4.5scfm@90psi will usually come on once per tire. Its max tank pressure is 125 and it comes on just under 100psi. If something's stuck, it'll run well under 90psi but that might be the fault of the gun.

I have a cheap ____ 1/2" impact gun. I'm working on getting a used pro tool somewhere, with something more like 400-650 ft-lb of loosening torque available. On a quick study of the different mechanical builds of different guns I've found that some are very wasteful of air, and some make the most of it. I'm not sure what kind of gun DaveH has - it could be very inefficient like mine.

Where I find my setup could be lacking is in continuous duty like painting or sand blasting. This work is done at 40psi, and the compressors are rated with scfm at 40 and 90psi. I think mine is 5.5scfm@40psi. I'm not sure that it can keep a full sized sprayer going for very long without taking a rest to build pressure in the tank. It hasn't let me down yet however.