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What type and size air compressor (HP, Tank Size, CFM, direct drive/2 stage... etc) would be suitable for a home garage where I'm going to do small amounts of maintenance but nothing major?
So I would need to be able to use a tyre inflator and a impact wrench, I'd like to be able to do small amounts of spray painting but I don't plan to respray an entire car.

(I'm not asking about specific brands or a models, I want more general info than that)

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2 Answers 2

up vote 7 down vote accepted

I would suggest looking at the tools you plan to purchase for use with the compressor.

Air tools will list what CFM @ X PSI they need to operate.

That is the most important number, to make sure it can supply the air flow your tools need to run.

Beyond that, horsepower and tank size are going to be how much money you are willing to spend.

A larger tank will be able to supply air for longer, higher horsepower will be able to fill a tank faster.

Horsepower typically goes up with tank size otherwise the fill times would get severely long but check the ratios of Power to Size. For example I've seen a 2.5HP 8 gallon and a 2.5HP 10 gallon in the same product line. So in that case, the 8 gallon can fill faster and was actually rated to provide higher CFM.

Inflating tires, pretty much any compressor can do.

Impact Wrench (guessing that is what you mean be Rattle Gun) I've seen call for 3-8 CFM @ 90 PSI depending on drive size, torque rating and manufacturer.

Air Ratchets, I've seen 3-5 CFM @ 90 PSI.

The tools that really eat up your air supply are the ones that you keep on for longer periods of time such as grinders and cut off tools. An impact wrench should do its job with a couple quick pulls of the trigger whereas a grinder you can have on for several minutes at a time when you are working on a piece.

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[+1] on the ** 3-5 CFM @ 90 PSI** portion. That's what I was about to suggest. –  jp2code Jun 14 '11 at 17:39
So basically, a smaller tank will need to be filled up more often, so the motor will run more often... Can it affect the tool performance if the motor is running? –  Gabriel Mongeon Jul 14 '11 at 13:33
@Gabriel, the more HP the motor has the quicker it is going to be able to fill the tank or the more CFM outbound it is going to be able to make up for. –  ManiacZX Jul 14 '11 at 15:53

Painting tends to use a lot of air (CFM) at low pressure (<50psi, typically). So do sanders. Air sanders are great if you are planning on doing bodywork of any kind.

Review your air tool requirements as @ManiacZX recommends. Painting is an enjoyable activity with challenges; getting paint that matches exactly is almost impossible. You will need an oil/water separator for tools like paint sprayers and sanders that run much longer than most tools.

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