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Old 05-25-2007, 01:29 PM
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beginner question on compressor cfm

Hi Im new to painting cars and shopping around for compressors.. on a low budget. I looked around the forum alot and reading how you must have a compressor with enough cfm.
My newbie question is... so if I had a gun that requires 10cfm @40psi but my compressor supplies 8cfm, what happens exactly? Does the air shoot out with less power(as a result cant utilize the guns atomizing capability)? or is it a matter of the tank running out quickly and having to refill often?
Thank you
Kevin

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Old 05-25-2007, 01:45 PM
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What will happen is when you get to a certain pressure your compressor runs out of air that produces the correct amount of air for atomization of the paint. You'l get spits of paint out or terrible orange peel. What might be handy is if you get to a point to where you can tell the difference..and you can...stop spraying and let the compressor catch up. Try to keep the areas you are painting in sections...the wait a while...however long it takes for the compressor to catch up. You want to make sure you finish a section because then you will have a different problem. One way to get around low air pressure is to paint your car apart, fenders, hood, doors, trunk lid and so on. That way you can paint a door and let your compressor catch up..paint another door let your compressor catch up. Know what I mean?
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Old 05-25-2007, 05:31 PM
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thank you for clearing that up.
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Old 05-25-2007, 06:26 PM
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If it is close you should have no problem, remember the gun is not spraying anywhere near 100% of the time.
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Old 07-26-2007, 12:38 PM
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i use a 60 gal compressor that puts out around 12 cfm and my hvlp gun sucks up every bit of it. But when the compressor kicks on, i trigger the gun for air only and i dont see any pressure drop so i keep painting until im done that panel. Then i wait for it to catch up before starting the next panel. I havent seen a noticeable diff in the finish, but I assume i would if i kept going continuously. Its a devilbiss gun that needs around 15psi when triggered...i usually set the regulator at the compressor at around 45ibs, then turn it down on the gun to around 15.
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Old 08-07-2007, 12:09 PM
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I also have a question. I have been looking around for compressors to rent and the CFMs that I am finding are ranging from 80-185 CFM. Would that be safe to use? All of the guns I find are rated no where near that.

Thanks for the help!
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Old 08-07-2007, 01:19 PM
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That sounds more like a jack hammer compressor.
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Old 08-07-2007, 01:19 PM
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That makes sense. Thanks. I guess I'd better keep looking.
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Old 08-09-2007, 05:02 PM
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Quote:
Originally Posted by tommyt
I also have a question. I have been looking around for compressors to rent and the CFMs that I am finding are ranging from 80-185 CFM. Would that be safe to use? All of the guns I find are rated no where near that.

Thanks for the help!
Are you sure you're not confusing cfm with psi? I've never heard of a compressor with that kind of cfm, but that is the typical range for psi.
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Old 08-09-2007, 05:10 PM
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Since these are from a rental place they probably are diesel powered industrial compressors that can run that much CFM and more. You probably could paint a car with one however that would be sort of like using dynamite to rid your yard of ants, it would work BUT
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