Hi all,
I recently adopted an older compressor – I’m guessing it’s about 20 years old. I really want to start getting into spraying finishes after having only brushed or hand rubbed my finishes to date. Lacquer, in particular, is my goal.
The problem I have is that I have no idea what the cfm rating is for the compressor, so it’s hard to match this against a suitable spray gun which I will need to purchase. I do know it is rated at 1.5 hp. When I talk to people about this, they quickly jump to the conclusion that it will only spit out 3 (or so) cfm. When I look at some of the new compressors on the market rated at 2 or even 3 hp, I can’t help but think mine easily matches them in output. Though rated at a higher hp than mine, they only draw 8-12 amps. Mine has a Doerr motor that draws 21 amps (on 115) and has dual cylinders. I don’t want to make a mistake a buy a gun that it can’t power, but I also don’t want to invest in an expensive touch up gun when I could have purchased a more powerful unit. Is there any way I can measure the cfm rating? I’ve searched the net for info on the specific motor and came up empty. I’ve heard stories of older 1.5 hp units pushing 10 cfm, and can’t help but think mine may be in that category or close to it. Any thoughts? Many thanks.
Replies
Would say that a compressor as you describe would have no trouble with most spray guns.
Of course, it has to be in decent working order, have the presure switch cut-off set right, and a presure regulator, also set correctly.
Would suggest you can start with an inexpenssive gun and THEN determine your further needs.
For furniture, guns are not as critical as for automotive spraying.
HVLP conventional guns would say are the better option, with a cup on top. They have low-cost ones at e-bay for about $20.00, and at grainger, one that is pretty much all needed for furniture is about $120.00
However, the compressor is used in the shop for many, many uses.
Use will tell you if the compressor is OK. If any thing not quite OK, they are not hard to fix, unless the heads are bad. The rest is accessories.
Good luck.
-mbl-
If you want to find a good gun at an unbelievably low price go to
http://order.harborfreight.com:80/EasyAsk/harborfreight/results.jsp and get 43760-1VGA.
For $15 you can't go too badly wrong.
The tank's capacity is important to maintain
the volume of air needed to do constant spraying
and keep or build up a reserve during rest periods
It must have time to re fill to keep up. If your tank is not large enough, it is relatively easy to add an auxiliary tank to increase your capacity.
Steinmetz.
Edited 1/8/2005 11:59 pm ET by steinmetz
Joel,
I did a quick search at google.com for "calculating cfm air compressor" and got some links that look promising. Here's one of them - http://www.aircompeq.com/formulas.html . It looks like you should be able to figure out the CFM by timing the compressor as it fills the tank to a set pressure.
Website
Thanks for all your advice everyone. Paul, the website you pointed me to was very useful. As I suspected, my compressor is pushing out in excess of 6 cfm according to their calcualtions.
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