Thread: air compressor

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going to start to learn how to paint a car. have alot of old spare metal to pratice on. my question is what is the minimum air compressor psi that i need to do a good job.

It depends on what kind of gun you get. The compressor must exceed the CFM rating of the paint gun... Usually for home use a 5 hp with a 60 or 80 gallon tank is more than sufficient.... Buy a bigger compressor then you need right now!!! Once you start using air tools and paint guns you'll just end up getting more!!!!

One that puts out a lot of CFM. Most paint guns, HVLP or even suction, require at least 9.5 cfm for uniform performance. Many require up to 16 cfm or more. Regardless of the PSI rating or the HP rating, the CFM is usually the most important factor. Now to get that level of output, you'd probably be looking at a 60 gal to 80 gal twin cylinder compressor at the least. Most smaller compressors won't handle the cfm requirements of automotive paint guns.

That's not to say that you can't do paint work with a smaller compressor, it's just that it requires more effort and time to get a good finish. I know a guy who has painted a number of cars with excellent results using a 30 gal compressor with a 6.5 cfm rating. Because of the smaller tanks these units have to work much harder than those with 60 or 80 or larger tanks. With the larger units there is less time lost waiting for the compressor to catch it's breath. There is also a huge difference between industrial grade compressors and your general grade of compressors. As with many things, quality and value comes with a cost.

I am sure some of the others here, like Hotrodpaint, can give you a far better and more precise answer than I can. They've probably done more painting in one year than I will do in 20 years.

I notice you are asking about PSI. Again, it depends on the kind of gun, but with the gravity fed guns I have, I have been shooting at about 30-35 psi. Primer seemed to need a little more, as it is thicker.

If you are concerned about compressor capacity, the bigger ones really make life easier and can keep up better, as the guys suggested. But for years I got by with a little Sears 2 HP/20 gallon portable compressor, and painted a few cars and a couple of boats with it. It just ran constantly though, and sometimes I would have to wait for it to catch up.

This is one of those instances where bigger really is better.

Don

I am in need of a bigger compressor and just waiting for next tax return I guess and some kindness from the wife. Bigger at the beginning is definitely better, as you'll likely need it later and could have put the money towards it to begin with.

I have a small single stage Quincy, 30 gallon tank, only about 3cfm. I want to start doing some sandblasting (not car related) and it isn't going to be enough. I plan on getting a big Quincy on an 80 gallon tank (quincy are like the rolls royce of compressors, very high quality, you find them in a lot of shops and businesses that need reliable equipment). I'm looking at about 1700 including tax for the one I want.

You want to get what I think they call a Pilot Valve unloader. basically rather tahn the compressor running and then kicking off when at pressure and then kicking on again when it gets low enough you can use the pilot valve to keep it running all the time (less stress on the motor and pump) and the unloader lets the air pass when it hits the top of the pressure level you have set. I think I explained that right, from how I understand it.

Red

thank you everyone for all the great answers. i will let you all know how i get along with my new endeavor

I have a big dryer/water trap on mine, must be about 4" diameter and about 8" tall. It is bottom drain, but since it is a horizontal it's not as effective as if it were on the bottom of a vertical tanked unit. I plan on getting vertical for space reasons as well.

The compressor I want, 19cfm at 90psi

One other thing to think about too. depending on the size of the space you are using for your shop/paint booth etc. you can take the compressor and mount it outside, or out of the way, and run hard line (pipe) to different locations with quick connects. really beats dragging a hose around everywhere. Just another thing to think about.

Red