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Air compressor suggestion
http://luthiersforum.com/forum/viewtopic.php?f=10101&t=42577		 Page 1 of 1
Author:  sprouseod [ Wed Jan 29, 2014 7:47 pm ]
Post subject:  Air compressor suggestion
So my HF 8 gal compressor finally died. I'm looking for new with the best value. I use the compressor mostly for blowing off debris, some small tools i.e. small nail gun and ordinal sander. I have a Fugi Turbine spray system but I also have a good Walcom Slim S HVLP that I would like to be able to use as well. Keeping price in mind what would you suggest?

Thanks
Richard
Author:  Spyder [ Thu Jan 30, 2014 12:28 am ]
Post subject:  Re: Air compressor suggestion
Look at the specs of your equipment, the HVLP and others, and find the air requirement, if it is listed. Remember that in compressors, what is important is CFM AT PRESSURE, not Max CFM, or HP. Get one with the highest rating you can afford.

If the one that just died was sufficient for your needs, look up the specs for it, and find another with at least that much output.

Hope this helps,
Author:  sprouseod [ Thu Jan 30, 2014 8:25 am ]
Post subject:  Re: Air compressor suggestion
The Walcom hvlp uses 6.6 CFM at 29 PSI. One small compressor that l looked at was 45.cfm@90 and 5.5cfm @40. How do I figure out what the CFM is at 29PSI? Also is there any difference in quality of the pressurized air. It seems like my old one would spit out very small amounts of oil at times.

Thanks
Richard
Author:  chiptheshrink [ Thu Jan 30, 2014 9:39 am ]
Post subject:  Re: Air compressor suggestion
A little bigger than you need is better than barely big enough... As for the oil, a good filter is really essential, I use two in line. It's not that different from a car, if you use oil to lubricate a piston and cylinder, a certain amount of it will get through to the "exhaust." And a longer run of hard pipe between the compressor and end use, with a drain at a low point, will help as well, especially with condensation, which is also inevitable as warmer compressed air cools. The condensation issue is helped by a larger tank as well, so that you aren't taking a small volume of recently compressed air, which will be hotter as a function of compressing it, and then letting it expand and cool immediately. Hope that helps!
Author:  Tai Fu [ Sat Feb 01, 2014 3:59 am ]
Post subject:  Re: Air compressor suggestion
What kind of orbital sander do you have? I thought they all require at least 20 CFM @90 psi (meaning you need at least a 5hp belt driven compressor).

I would say if you can find a belt driven, at least 2HP. It should more than suit your needs.
Author:  Clay S. [ Sat Feb 01, 2014 9:18 am ]
Post subject:  Re: Air compressor suggestion
"The Walcom hvlp uses 6.6 CFM at 29 PSI. One small compressor that l looked at was 45.cfm@90 and 5.5cfm @40. How do I figure out what the CFM is at 29PSI? Also is there any difference in quality of the pressurized air. It seems like my old one would spit out very small amounts of oil at times."

It's difficult to calculate the amount of cfm for a given pressure as it depends on the design of the machinery, so it is usually measured at a couple of different pressures. Assuming you are spraying guitars and it has a reasonably sized air tank that compressor would probably work fine.
The air sander is usually the real air hog and that compressor might not keep up if you do much sanding with the orbital.
Author:  Spyder [ Sun Feb 02, 2014 12:19 am ]
Post subject:  Re: Air compressor suggestion
In a past life, we had performance curves for our compressors. That way you could look up the pressure you want, and it would tell you the flow rate. Not sure if they are available for the compressor you're interested, might be worth a check on the net.

If you need 6.6 cfm at 29 psi and the compressor gives 5.5 at 40, my guess is the compressor will be running close to full time to keep up.

Again, I would suggest looking up the performance specs for the one that went blooey, and go from there. Was it enough? Need more air? Etc.

Oh, and that would be 4.5 cfm at 90, not 45! [:Y:]
Author:  RusRob [ Sun Feb 02, 2014 4:32 pm ]
Post subject:  Re: Air compressor suggestion
I painted cars for years and still on occasion do a few small custom jobs here and there so in my opinion you want to get about 4X the compressor than you think you need. There are a couple of reasons, 1. Larger tank will hold more volume so your compressor will not run nearly as much. It will run longer to fill the tank but if the compressor motor is large enough it will fill the tank quickly. 2. Running less will extend the life of your compressor motor.

I have had a number of compressors and have also burned out a number. The ones that have burned out quicker are small ones that can't keep up. Depending on the tool you are using they can use up a lot of CFM. I not only have my spray guns but also a die grinder, regular grinder and Dual action sander which I use on guitars. I also have a large and small impact wrench, hand held buffer and air chisel that I use on other things around the garage and of course my nail guns. Even though I have not been in the body painting business for 30 years I would have a hard time living without my compressor and air tools. They are lighter and smaller than most electrics and don't burn out ( have not had to replace a single air tool I have ever bought).

As for regulator/ filters, It is a really good idea to get a self draining filter, mine is an old DeVilbiss but it self drains by "spitting" every so often which keeps the crap out of the line. For spraying I always use a disposable in-line filter which attaches to the end of the line and filters out anything the regulator doesn't so you get perfectly clean air at the end of the line. A hose with compressed air will produce water no matter what you do especially as the outside temp rises. So a cheap disposable filter is a must for spraying.

Here is the type I use:

http://www.ebay.com/itm/DISPOSABLE-INLINE-Moisture-AIR-WATER-FILTER-Paint-Spray-Gun-Tool-IN-LINE-FILTER-/191056529302

So from an old body shop guy.... Much bigger is always better... laughing6-hehe

Cheers,
Bob
Author:  sprouseod [ Sun Feb 02, 2014 9:29 pm ]
Post subject:  Re: Air compressor suggestion
Thanks for all the input. Picked up a 33gal upright compressor from HD on clearance. It should take care of my limited needs

Richard
Author:  Tai Fu [ Mon Feb 03, 2014 8:07 am ]
Post subject:  Re: Air compressor suggestion
I heard automatic drains can clog.. so just remember to drain the thing. Plumbing isnt necessary if you dont mind extending air hoses. However noise suppression is probably necessary if your neighbor is close...
Author:  Tai Fu [ Mon Feb 03, 2014 9:13 am ]
Post subject:  Re: Air compressor suggestion
Copper pipes do not exist in Taiwan, only option is either steel or PVC. When I ask about compressor plumbing they tell me to use PVC. Maybe I can use refrigerator piping (which is copper)?

My compressor doesn't get that much use so I just use a hose. It's not large enough to make permanent plumbing beneficial.
Author:  Clay S. [ Mon Feb 03, 2014 10:53 am ]
Post subject:  Re: Air compressor suggestion
"When I ask about compressor plumbing they tell me to use PVC"

PVC is not a great choice. Although cheap and easy to install it has a tendency to shatter unexpectedly and send fragments flying through the air. I would rather tack an air hose to the wall (with all the resultant losses) than use PVC. Black iron is fairly cheap and holds up pretty well.
Author:  RusRob [ Mon Feb 03, 2014 6:14 pm ]
Post subject:  Re: Air compressor suggestion
Never use PVC.... It gets brittle over time and Clay is correct, it will explode.

I am trying to set up my new shop and am considering PEX. It isn't rated for more than about 100 lbs so it needs to be regulated at the compressor. It is probably the least expensive route.

Also if running any length of pipe of any kind it needs to slope down hill to the compressor to keep the moisture from running TO the tool. A good practice done in most shops is to create a U in the line just after the compressor where you put your water trap. Usually lines run about waist high and the U goes down almost to the floor. That seems to do a pretty good job of removing any moisture from the lines. And I always use a disposable filter at the end. I use snap connectors on my hose and tools so I put a male on the inlet of the disposable and a female on the exit. I can then either plug it in right at the tool or run a short section of hose from it to my tool. On my spray guns and air brush I run the small section so the filter is not in my way.

Bob
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