How do I choose a stationary compressor?

[Brian Elfert]

I'm looking to buy a stationary air compressor for my shop to do various things including running air tools to do body work on a vehicle.

Anything special I should look for in a compressor? I'm thinking one of the 3 HP 60 gallon compressors like the Husky at Home Depot for $399. I believe the Husky is made by Campbell-Hausfield. It does have a cast iron compressor unlike some of the others with aluminum. I believe Sanborn also makes a unit for the same price, but not sure if compressor is cast iron or aluminum.

There is a local company that makes really nice compressors, but they charge over $500 for basically the same as the Husky or Sanbirn unit.

I've looked on Craigslist, but a lot of folks think their compressors are made of gold. Older units that are don't look the best are same price as new. There is one listed now made by a local company for $500 that I am considering. It is a $1200 compressor new and is big enough to run any air tool. Not sure if I want to spend the additional $100 over new or not.

[Jim Becker]

Brian, the local concern or a top line manufacturer's product might look like the Husky, etc., at the 'borg, but they are much better products and worth the extra cost. The better compressors are also easier to repair in the future because the don't cut corners on the plumbing, etc. (Ask Dennis Peacock about his experience with a 'borg compressor...or see if you can find it using the advanced search here at SMC) This is one of the reasons I went with an IR 60 gallon 3hp unit for my own shop. I caught a sale at Tractor Supply for about $500 and couldn't be happier. Note I'm not saying that the Husky, etc., are "bad" machines...just that they are not built to the same quality as those from companies specializing in the trade rather than the mass market.

Oh, and some of those older compressors, despite looking yucky, are darn good machines with high-quality manufacturing. 'Requires some homework, but don't rule them out.

[Randal Stevenson]

First gather all your current tools specs!
Then gather the tool specs of your planned future tools.
Find out the MAXIMUM CFM that they require (this will most likely be a sander, or grinder/body shaping tool, not a impact)
Buy a compressor that will exceed that! Cast iron is good, larger tank then expecting, is good (oversize your airlines, and they act as a extra tank, aka 3/4 instead of 1/2), oil lubed is a REQUIREMENT on one of this size. (prolong it by proper maintainence, like a car).
Twin cylinder is better, but I worked in a garage where we did have/use a single cylinder (effectively homeowner) style. While there are a lot of homeowner ones, there aren't that many run for 40 year style anymore (can be found online and at a few commercial places).


EDIT, Not twin cylinder, TWO STAGE (brain fart). We used a single stage one after a failure of the 40 year old two stage one, since the place had been remodeled, and there was no physical way to get the new two stage (of the same size), in there.

[Mike Goetzke]

I'm by no means a compressor expert but here's my thoughts:

I currently have a 25 gal. oil-less compressor and a 6-gal. pancake compressor. I use the smaller one probably 95% of the time for my pin/finish/brad/crown stapler-nailers. For automotive and spray gun I use the larger one.

I'm currently looking for a larger compressor too for two reasons: 1) the oil-less compressors are so LOUD! 2) my larger compressor has a 90psi cfm rating of 5.7 and can barely keep up with my HVLP gun.

The Husky you mentioned doesn't have a great rating as far as cfm. I also have been looking at CL and noticed many want new or better prices for their used equipment. Two compressors that caught my eye were at Lowe's. They have a Campbell-Hausfeld 60 gal and 80 gal.. The 60 has a rating of around 11 cfm at 90 but the 80 has around 16. The 80 was $650. I read somewhere that you should look for a compressor with a cast iron pump - not aluminum with CI sleeves. One thing to remember is that these larger compressors require 220V power.

[Brian Elfert]

I am absolutely going with an oiled compressor. I want one with a motor and belt. There are a few oiled ones that are direct drive.

The C-Aire compressor for $500 is probably one of the best deals I will ever find. It is true 5 HP with a two stage compressor. It also does over 20 SCFM at 90 PSI. C-Aire is a local manufacturer that make some real nice, but expensive compressors.

[Steven Wilson]

Brian, the C-Aire is fine and that's a decent compressor especially at that price point. You may want to consider the next one up with a larger tank as you mention the use use of autobody tools.

[JayStPeter]

I have the 60 gal/3HP CH compressor. It hits it's limit pretty often with auto tools. 2-stage is definitely the way to go.

[Brian Elfert]

Brian, the C-Aire is fine and that's a decent compressor especially at that price point. You may want to consider the next one up with a larger tank as you mention the use use of autobody tools.

The compressor I am looking at is used. The step up from an 80 to a 120 gallon tank would be extremely expensive. Only C-Aire's most expensive line has a 120 gallon tank available and finding one used is not likely.

[Jim Thiel]

The C-Aire compressor for $500 is probably one of the best deals I will ever find. It is true 5 HP with a two stage compressor.

Should you decide that you don't want that deal, LMK. I'll come by and kick you in the shins until you change your mind.

Seriously, a 5hp two stage for five bills? You don't have it yet?

Jim

[Brian Elfert]

Should you decide that you don't want that deal, LMK. I'll come by and kick you in the shins until you change your mind.

Seriously, a 5hp two stage for five bills? You don't have it yet?

I've exchanged emails with the guy and will call the guy shortly.

[Ben Cadotte]

I have had very good luck with my 3.5 hp (actual) 45 gallon Kobalt. Longest waranty of any large department / borg store. It has a respectiable CFM capacity, little higher than even some 60 gallon units. It will run down with an air sander held wide open though. But I don't use it all the time so I felt the 45 gallon tank was a good size for me. Much quieter than my Craftsman 25 gallon noise maker. Not silent but wont scare you when the shop is quiet and all of a sudden it kicks on.

[Joe Jensen]

In my quest for my latest compressor, I read a ton on the subject. I think there are some myths in this thread.
1) 2 stage is necessary for PSI over 100-120. If you only need less than 100 PSI, a similar price point 2 cylinder 1 stage will make more air per HP than a 2 stage. For example, Quincy makes a 2 stage model 325 that takes 3-5HP. Their comparable 1 stage is a model 240. It also takes 3-5HP, and it makes more air at 100PSI than the 325 with the same HP.
2) Tank size is not the critical factor. In any high volume application the tank will empty very quickly. This is easy to prove to yourself. Fill your tank and then see how quickly the pressure drops below your working pressure. I read that you want at least 1 gallon of tank for every CFM the compressor produces. Larger tanks let the compressor cycle less often but as you approach the max CFM the pump can produce, tank size becomes irrelevent.

Here is a good link to truth in compressors.
http://www.truetex.com/aircompressors.htm
I like the rules of thumb listed here from the link.

Rules of thumb:

• A good compressor, per true HP, will deliver about 4 true CFM at 100 psig.
• The tank should be sized to be at least 1 gallon of volume per CFM of the compressor.
• Uncooled compressed air is hot, as much as 250 to 350 deg F!
• Many tools require more CFM at 90 psi than what is physically possible to get from the power available through a 120 VAC outlet. If you don't observe this physical reality, then either your tool won't run right, or you won't be able to run it at a decent duty cycle.
• Beware also, that the CFM figure given as the required air power on many tools (e.g., air chisels/hammers, sandblasters) is for an absurdly low duty cycle. You just can't run these constantly on anything but a monster compressor, but the manufacturer still wants you to believe you can, so you will buy the tool.

[Brian Elfert]

Dang it! The guy sold the compressor literally 10 to 15 minutes before I would have been there. I was on the road over to his house when he called to say it was sold. He did tell me when I called that someone else was also on the way over. I should have called right away Sunday evening. Oh well, at least I wasn't too far from home.

Maybe the malfunctioning traffic light and the accident on the freeway were omens that I shouldn't buy a compressor right now. I probably spent 15 minutes or more sitting in traffic.

I should probably just buy a compressor at Home Depot for $400 as I have a need for a compressor in the next week or two. I could probably search Craig's List until next fall and never find another deal as good as the one I missed. With my luck all I would see on CL is gold plated compressors or ones that are rusty and worn out.

[Brian Elfert]

Yes, I realize any decent compressor will require a 220 volt circuit. I can fairly easily run one out to the garage where my shop is for now.

[Brad Shipton]

Only thing I will add is that you will need between 10 - 20cfm to run many autobody tools continuously. They are much worse than woodworking tools since most are open ports and you need to run non-stop. Having tried running one on less than required I can say it is a royal pain to do so.

Brad