Compressor recommendations

You can get by with one of those you have named -- all the homeowner brands -- but you will not like them. And by "getting by" I don't mean you'll be able to do whatever you think you need to. You won't have enough air with that thing to run a die grinder or any kind of rotary air tool. They are made mostly for nail guns. And they are *cheap* used.

The prevailing wisdom on thig NG is to buy used industrial gear. No, it isn't shiny anymore, and yes you have to know a little bit to get something useful, but I see really usable industrial air compressors all the time in my area in your price range. Try your local craigslist - visit

and pick the closest city, go from there. Watch it for awhile.

GWE

How much air do you want? Where are you? Can you get to a used dealer in a big city? Have you looked in the classifieds in your area?

I owned a "Harbor Freight pancake compressor" and hated every minute of owning it.

for a good reason.

Compressors are very easy to get. Yes, used industrial gear is way superior to the "cheap stuff", in the medium run. I second the recommendation to look for a used good honest compressor. Do not waste time and money on consumer grade crap. (unless you need portability, for example you are a home improvement contractor)

If a compressor has a label saying "Peak HP" or "Maximum developed HP", or "Peak CFM", stay away from it. An easy rule of thumb is to look at amp rating of motors. 1 HP is roughly 6 amps at 110V. The amp ratings are more realistic.

i

Ignore the HP ratings. The only meaningful rating is free air CFM at

90 PSI. There are a few "consumer" 5 HP units that will deliver about 11 CFM at 90 PSI. They're OK for occasional use, and they will run most tools including a diegrinder, DA sander, chisels, sprayer, impact wrench, etc.

A true 5HP 220-volt motor draws at least 20 amps. There are plenty of 5 HP compressors that still don't deliver much air -- and there are some industrial pumps that can do > 11 CFM with 3 HP. Small pumps are all inefficient, but there is a huge variance in how inefficient. Theoretical power +15% friction to deliver 11 CFM at 90 PSI with adiabitic compression (no cooling during compression) ) is only 2.15 HP!

Look at the pulley sizes and motor RPM, do some arithmetic. Low pump speed (1100 RPM or less) is quieter and lasts longer. Stay away from direct drive units.

The industrial jobs (Quincy, Ingersoll, et al) are definitely better machines, but if your use is "weekender" type where the thing will run for a few hours on some weekends, I think you'd be happy with one of the better "consumer" jobs -- as long as it can deliver enough air. I know several guys that have had them for over a decade. I saw one a few weeks ago at a Farm & Fleet for about $450 that looked OK.

I would avoid brands like Campbell Hausfeld and Coleman. I'm not familiar with Husky.

Hm. Check out

from Northern Tool for $430. It's only 3.6 HP, 15 amps but delivers 11.2 CFM at 90 PSI.

I'll second that and suggest ignoring any unit that can't produce at least

12 CFM @ 90 PSI with at least a 20 gallon tank.

I bought a Porter Cable "Job Boss" [model 3151 iirc] that was "rated" at 6.2 CFM @ 90 PSI. It won't keep up with a Campbell-Hausfeld 6 CMF die grinder. Oh, it'll run it for a short period but not continuously and a sander is out of the question.

If you have any desire to do any sand/bead/shot blasting you'll need up to

30 CFM.

Just a data point, I can run my air angle grinder, or orbital sander, on my compressor all day long. I tried. I have a 3 HP compressor (3 honest HP, with a big Baldor motor). I am not even sure what my compressor CFM is, probably about 11-12 CFM.

i

That's another issue - just as these consumer-grade air compressor vendors overrate the CFM ratings for compressors, so they underrate the CFM on their air tools. I have yet to see an air die grinder which doesn't require a solid 15 CFM at 90 psi to run the air pump at 50% duty cycle or below which is what you should have to avoid wearing out your compressor.

Not 6 CFM. Not 10 CFM. FIFTEEN CFM.

GWE

A small blast cabinet with an S-25 siphon gun from TP Tools works fine on 10 CFM. Not for big jobs, but it's great for small stuff.

Which sez your diegrinders need about 7.5 CFM. Diff'rent strokes for diff'rnt folks. Weekend workers are not gonna be running a diegrinder 16 hours per weekend most weekends. Sauce for goose 'n gander, etc.

I don't know of any "weekend shop" guy that hasn't been satisfied with his "consumer" 11CFM or so compressor.

I think we "advisors" should separate "whut I have" from "whut you should have" when needs of askers may be different from ours.

Well said, Don. Every guy has different needs. A consumer-grade compressor might suit you well. If you want a brand new compressor, don't want to spend time tinkering with it, and don't mind a machine which might need replacing in a few years, go for it. But if you like tinkering, want a compressor which will last, and the air to drive your

43 CFM Ingersoll-Rand die grinder (they do make one, I'll find the model number if you like) go for the ex-industrial unit.

Chris

I have a Porter Cable "7HP" 60 gallon compressor that keeps up with every tool I have, die grinders, air drills, DA sander. Granted it will not run 24 hours a day powering the tool, but with my use the worst that happens is the compressor runs constantly while the tool is in use. The pressure never drops enough that I have to stop and take a break for the compressor to catch up. For the weekend warrior 10 CFM is just enough. Greg

All too true, Chris.

One of my key considerations was portability and this one fits nicely between the tailgate of my pickup and the fifth-wheel hitch. It also sits 6" below the bed rails.

It runs easily from a 15A 120V circuit - available on the outside of my RV - when the generator is running. This allows me to use a few basic pneumatic tools such as an impact wrench and ratchet in the event of a flat tire "in the middle of nowhere".

Don: here's one "weekend shop" guy that's going to be looking for something in the 15+ CFM range with as much storage capacity as I can get that'll run on 240V single-phase. [Emphasis on the "+"]

My goal will be to have enough capacity to consider doing light-to-medium sand/bead blasting and, if the comments posted here are even "near the ballpark", there are few pneumatic applications that require more airflow than that.

Unfortunately, for me, the "stuff" that I'd like to clean up won't quite fit in it.

You can save a lot of $$$ if you make your own 3 phase electricity and buy used 3 phase compressor and other tools.

i

I am quite happy with the performance from my $12 die grinder powered by my 1/2 HP, 2CFM compressor. Of course if I found a 15 CFM compressor and appropriate motor for the money invested in the present setup ( less than $10 ) I wouldn't turn it down. Gerry :-)} London, Canada

You can get an 18 CFM Ingersoll single stage for about $800.

Since you want storage capacity, I'd encourage you to look at a two-stage. They are noticably more efficient (more CFM per HP), and their capacity is nearly the same at 175 PSI as it is 90 PSI. Having your reservoir at 175 PSI rather than 125 PSI more than doubles its capacity for given volume, for shop air regulated to 90 PSI.