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Old 05-20-2006, 04:18 PM
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Help me buy my 1st compressor

Hello all. Newbie here looking to start getting into painting cars. I'm in college so don't have much to spend, around $500 for a compressor. These are the two I'm looking at

Coleman 7hp 60 Gal

Kobalt 7hp 60 Gal

The Coleman says it puts out 12.3 CFM @ 90, the Kobalt says 13.3 SCFM @ 90. Should they really be that much different since they are both 7 peak HP 60 Gal? Is it worth spending the extra $70 to get the Kobalt? And do you think that the Coleman, if I got that, would work good enough for painting assuming I use new painting technology (HVLP etc.)?

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Old 05-20-2006, 08:02 PM
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Shyne, Ratings on the home shop type compressors have gotten ridiculous in the last few years, to the point of being almost meaningless. Both of the compressors you mention are about the same from a performance standpoint and unfortunately they are both overrated somewhat. Those HP ratings are not even close and both are around only 3 1/2 HP actual power output and you really will only be able to count on about 11-12 SCFM@90 PSI. The good news here is that those figures are not really all that bad it is just that we have become accustomed to all the garbage numbers these rascals have been listing the last few years so when we look at honest numbers it looks like poor performance when it really is not. You can look at the AMP rating on the motor and get an idea of the real power, a 5 true HP motor will be rated around 24-28 AMPS@240 volts and I am willing to bet both of those outfits are only 15 AMPs but that does not mean they are under powered, at least not in that price range. HP by itself really does not determine the CFM and tank size has nothing to do with it. The only numbers that really matter a lot is the CFM and most of the outfits today, while they may not be outright lying, are so reckless with the truth that even those numbers are usually suspect. No matter what the claims most 15 AMP motor, two cylinder, single stage, inline pump designs (by far the most common) are pretty much the same with the V type designs fairing a little better. Either of those compressors should do the job for you but you may find yourself waiting on it to catch up when using something as air hungry as a DA and it is minimal for a HVLP but it should still work just fine.

If you look closely at the Coleman CFM numbers I think you will find you are a bit mistaken, that 12.3 CFM is at 40 PSI and the 90 PSI rating is only a little over 10 CFM. While the Kobalt does claim to have over 13@90 PSI I really beleive them to be about the same it is just that the Coleman is giving honest figures for CFM. Also if you look at the Coleman 80 gallon vs the 60 gallon you will see that the CFM rating is EXACTLY the same yet they want another $220 for that extra 20 gallons Basicaly both of the Colemans are identical it is just that the one with the bigger tank will have fewer (but longer) on/off cycles during any given time period but the air output is exactly the same.

Last edited by oldred; 05-20-2006 at 08:22 PM.
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Old 05-20-2006, 10:21 PM
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Shyne, I have the Kobalt and it works fine for all my guns and also my palm da.

On the gun side I have all the finex types from sharpe, a devilbiss gfg-670 plus a devilbiss SRI, a Iwata lph-400lv. So if you intend using any of these or
similar you will be good to go.

I believe if you look closely at the pump you will see that the kobalt offers more cooling of the air. Before the air leaves the pump it goes through an
additional bolt on finned arrangement to the pump that cools the air.
"Less heat, less water in the tank".

The motor on the kobalt is rated at 16 amps 230v. I have never run out of air with mine. Running it in the heat of summer here in GA I found it to only produce a small ammount of water.

For the home garrage or small shop, I think you will do fine with the Kobalt.
If you decide to get it your going to need a external water seperator and high
flow 3/8" couplings and 3/8" id hose. BTW Modern air pump design is more efficient than air pumps of old, Hence the need to not have a giant motor to drive a efficient air pump that will roduce good scfm ratings.

><
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Old 05-21-2006, 07:19 AM
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I saw a review of a compressor online somewhere where is said the inside of the compressor was not coated and should be epoxy coated before use. Is this something someone would suggest I do when I buy a new compressor or is it not necessary? Thanks.

~Don
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Old 05-21-2006, 07:30 AM
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If I remember right, Coleman and Kobalt are made by the same company. Do a search in the Garage forum for the thread about choosing an air compressor and I think I posted a list of who makes what compressor. There are only about 4 manufacturers for all of the air compressors. If you are going to get into painting cars, I would save up a couple of more hundred and get a two stage compressor. You will be way happier in the longrun. A single stage has too much run time to catch up and generates heat. With the heat comes moisture. With the moisture comes paint problems unless you are setup with the system to catch all of the moisture. A two stage with a bigger tank has less cycle times and pumps up faster than a single stage so less heat, so less moisture. That and a single stage is quite a bit louder. If you can't swing the money, before you buy, shop around for a good used two stage compressor. Trust me, you'll be glad you did. If you do buy a single stage and are serious about your work, you will be upgrading in a year or two and your used single stage will only be worth around $100-200 on the market.
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Old 05-21-2006, 11:47 AM
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Kevin, What you are saying about the two stage is excellent advice. I could not get that dang Lowes site to load so I could not get all the info on the Kobalt and from what x711 is saying it would appear that it has a slight power advantage at 16 AMPs and probably a cast iron vs aluminum pump which accounts for the price difference. However I still have doubts about the 13.3 CFM claim although it will probably outperform the Coleman somewhat. When I still had my shop I did repair work on these things (several different brands) quite often and I found that in spite of the wide differences in performance claims the actual output of most popular brands of the same basic design and power range was about the same, these were checked with a flow meter and I was not guessing.

Shayn, Don't attempt to coat the inside of the tank with anything. Just drain it regularly and you won't have a problem.

x711, "less heat, less water in the tank"- not quite true. Since you will be cooling the air before it enters the tank that means you will be condensing the water vapor into liquid water before IT enters the tank resulting in more water collected in the tank, not less. This however is just a technicality and not a problem since the tank has to be drained anyway.
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