Replies

1. 
   forestgirl | Aug 29, 2002 07:19am | #1

   Steve, were I in your position I'd start by looking at the various air-powered tools and deciding which ones I'm most likely to need and buy in the next year or two, then look at the CFM and air pressure required by those tools.  Then start deciding on a specific compressor.

   forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl   ;-)

1. 
   rickkk1 | Aug 29, 2002 08:37am | #2

   if you have the room, get yourself a five horse,60 gallon tank, single stage is fine

   two stage is better but expensive. I have mine outside my garage in its own little

   hut and then just piped the air in (less noise) its pretty easy to set up. you can

   pick one up at a home improvement store for probably around $350.00 . for the

   money compared to what they get for small ones its your best buy, and like most

   things you can't have to much air.

2. 
   DennisS | Aug 29, 2002 09:17am | #3

   Steve -

   Sandor Nagyszalanczy's book "Setting up Shop" has a nice section on air compressor systems. See if they have it at the library. One thing to consider (based on Sandor's book) is if you intend to use the compressor for finishing. Don't overlook the possibility. Oil-less systems provide "cleaner" air for spray work.

   I would agree - bigger is better with respect to an air compressor. I've got a 3hp unit I got from my Dad that I've tried using for sand blasting (two stage unit). This takes *lots* of air, both pressure and volume, to get results (talking metal here).

   'course, if you never intend to do such things, that's another argument (grin)

   Dennis in Bellevue WA

   [email protected]

3. 
   riverr1 | Aug 29, 2002 06:58pm | #4

   IMO, the compressor is a tool that needs to decided on after you decide what you are going to use it for and what tools you are going to use with it. High end HVLP guns, quality air tools, etc. are not going to run properly with a small compressor. My Sharpe's HVLP's require 14 cfm alone, or they don't work right. There are some nice pnuematic clampling systems also that require a lot of air. Nail guns and blowing air doesn't require much of a compressor. One nice thing about compressors is the high end ones have an "hours of use" list for the compressor mech. itself. I bought a new Ingersoll Rand in the spring. At the time I saw that Porter Cable offered some large compressors at a much better price. I got a lesson on compressors by asking for comparisons. Things you don't see and aren't spec'd like if the pistons and rings are cast or steel make a big difference on the life of the compressor. There's a considerable difference between a life expectancy of 3k hours and 8k hours for another 3 or 4 hundred bucks.

   Don

4. 
   JeffKurtz | Sep 02, 2002 04:39am | #5

   Steve,

   I bought one of the oil-less models a couple years ago since I didn't really plan to use it a lot.  Boy am I glad!!! Not because I bought the compressor, but because I don't have to use it very often.  That thing is so noisy it drowns out the sound of my planer!  Carpenters were here a couple weeks ago putting a new roof on the house (I don't climb.) and they had a Dewalt with the two small tanks (looked like scuba gear) and I was amazed at how quietly it ran.

   Jeff

   
   

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   Edited 9/5/2002 6:29:29 PM ET by Jeff

5. 
   Glendo | Sep 02, 2002 08:18pm | #6

   Hi, I'd just like to add a few thoughts.

   Do not get an oil-free compressor, it won't hold up.

   Get the best filters you can afford, and also the best oil injectors if you plan to run air tools.

   Buy a larger one than you think you'll ever need.

   Lastly, replace the drain valve on the bottom of the tank with one that is easier

   to use...  and use it a lot! 

   Good Luck! ;~)

              Glendo

1. 
   Hannexx | Sep 11, 2002 05:08pm | #16

   I am currently getting into conversion HVLP spraying and have a question about air filtration. I have come across multiple statements similar to your “get the best filters you can afford” and “spend close to $100 for the filter” but cannot find a $100 air filter. I do not want moisture to be a problem so I am willing to spend the money now to prevent any hassle later. Can anybody offer a brand name, part number and supplier for a top-of-the-line air filter?

    

   Thanks,

   Don

1. 
   riverr1 | Sep 11, 2002 05:28pm | #17

   Check out Binks, Sharpe or even ingersol rand. They should have what you need. A good filter is a must. If you have water or oil coming out with your coating, you'll immediately know why as the stuff beads up and doesn't level out.

   Don

   Here you go:

   http://www.sharpe1.com/air-page.htm

   http://www.autobodystore.com/Filter/regulato.htm

   Edited 9/11/2002 10:31:42 AM ET by Don C.

   Edited 9/11/2002 10:34:59 AM ET by Don C.

6. 
   kahanj | Sep 10, 2002 10:31am | #7

   I'm an intermediate woodworker myself.  Fortuitously, I live in a neighborhood of carpenters:  GC next door, prop maker (set carpenter) across the street, construction coordinator (set carpenter who owns tools) up the street.  On any given weekend, all you hear are the screams of children and their fathers' saws, punctuated by the irregular thwaps of nail guns.  I purchased my first compressor a couple of years ago and, surprisingly, became the air king of the neighborhood for $150.  From this, I hit upon the central dichotomy in the air compressor world new versus used.

   Say what you will for the oil/oil-free debate, new and used has a clear winner -- used.  People turn these machines over constantly for a fraction of what they cost new.  For $150 I care a lot less if I have to rebuild an oil-less compressor far sooner than its lubricated brother.  Besides, with all the air tools the seller threw into the deal, the compressor was essentially free.  But I digress.

   Like you, I did not have a clear mission in mind for my compressor.  I had a couple of nail guns, wanted a blow gun, a tire chuck, a football needle, and a spray rig.  I recall reading a Chris Minick article in FWW, which I cannot now locate, in which the author said 5hp/20 gal. machines were the smallest practical machines for spraying.  Accordingly, I set that as my goal, notwithstanding my normal desire to over engineer every aspect of the shop by at least a factor of five.

   Here's why I didn't splurge on a giant industrial sized machine:  Giant industrial compressors are enormous and my shop isn't, they require a 220V feed and my sub-panel is essentially full, they take forever to charge and empty, and are typically lubricated -- requiring extra maintenance and an oil filter for both spray guns and my oil-free nailers.  The charging/emptying time is not something you should overlook.  If you want to shoot 3-4 nails or blow out one dirty tool on a Saturday afternoon, you don't want to wait 10 minutes while your compressor fills with air, 98% of which you plan to empty immediately after completing the job.  (The lubricated machines may be quieter filling, but every compressor is equally mind numbing with air hissing out of the bottom valve.)  If you live in a cold climate, the lubricated machines can be balky, if not downright recalcitrant about starting in the winter -- another drawback for those of us working in detached garages.

   Here's why I didn't buy one of those adorable little contractor deals with a pancake tank, or double hot dog (Emglo, Hitachi, DeWalt and the like):  They don't provide enough air to do anything other than shoot nails, they don't have wheels but the robust ones weigh an awful lot, even the lubricated ones are really loud, and they cost about as much as the 20 gallon machines.  Ultimately these small machines are built for accompanying their owners up ladders or into job sites.  I have no desire to pay for, much less make use of, such portability.

   All of this puts you, like me, in the mid-size compressor market (20 to 30 gallons/5 to 6 hp).  Whether Minick's article exists or not, the basic wisdom of the 5hp/20 gal. rule has proven true.  (As yet another in an endless stream of asides, let me hasten to add that this alleged 5hp rating is of the "peak" variety -- but all the manufacturers seem to use it, permitting you to compare apples to apples.)  My GC neighbor, upon whom I used to rely for an Emglo to power my nail guns, found his own rig really straining to run an HVLP conversion gun.  For a few months, he borrowed my compressor quite regularly and found it wholly satisfactory for spraying lacquer on large pieces of furniture.

   I have not personally sprayed finish with the compressor, but regularly run 100 feet of hose from my garage to the front of my house to drive nails.  Despite the pressure loss over the hose run, I have had no difficulty powering my finish gun or my brad nailer, both of which get sort of anemic if fed much less the 100 psi.

   Two more points:  If you can, get a vertical tank -- it'll take up less floor space and you lose nothing in mobility (of which you will have precious little, as 20 gallon cast iron compressors are heavy).  And if you do buy used, be unrelenting in the search for rust.  When the tanks rust, they can EXPLODE.  At 135 psi that 100 lb compressor represents a pretty substantial threat whether it breaks into pieces of shrapnel or simply takes flight as the world's least aerodynamic ballistic missile.  Besides looking for rust on the tank and fittings, fill the machine with air and empty it.  The water that comes out should run clear.  Otherwise, move on, there's a better bargain somewhere in the classifieds.

   So there's my $.02:  buy a used (hopefully charismatically ugly), oil-free (yeah it's loud, but you're a woodworker and can build it a little house or put on a pair of muffs), 20-30 gal., 5-6hp. machine.  Stick it in a corner with its own circuit breaker and congratulate yourself for purchasing all the machine you need for relatively little money.

   
   

   ---

   Edited 9/11/2002 3:04:54 AM ET by KAHANJ

1. 
   forestgirl | Sep 10, 2002 06:54pm | #12

   KAHANJ -- what a great post!  Thank you for getting my muscle-sore body off to a smiling start.  If I were a magazine editor, you'd be on my list for op-ed writers!  And, of course, thanks for the info.  I'm not in the market for a compressor today, but who knows about tomorrow, LOL!forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl   ;-)

2. 
   salinasteve | Sep 13, 2002 11:55pm | #18

   Thanks for a diatribe that is right up my alley.  Good information and very practical.  I've been amazed by the number of responsed I've received.  Thanks!

7. 
   LRutherfor1 | Sep 10, 2002 06:13pm | #8

   Forest Girl hit it right on the head.  Calculate your CFM demand and buy accordingly.  You get four (4) cfm per horsepower....A five (5) HP compressor will give you 20 CFM, but be careful choosing a hose.  A 3/8" hose will only allow 15 CFM, 1/2" will allow 25 CFM.

   Len (Len's Custom Woodworking)

1. 
   riverr1 | Sep 10, 2002 06:29pm | #9

   Len,

   Are you listing 4 cfm per hp as an example for the hoses? If not, I think you'd be hard pressed to find a 5 hp compressor that delivers 20 cfm. The 7 hp Porter Cable which is an inexpensive, but low quality compressor, only delivers 17.3 cfm at 40 psi.

   I could be wrong on this, but I don't ever remember seeing a compressor that delivers a high cfm being oil less either?? I think they just generate too much heat at that cfm not to have a reservoir of lubecoolant.

   Don

1. 
   LRutherfor1 | Sep 10, 2002 09:26pm | #13

   Please don't think I'm being a smart-aleck about this, but my wife owns a company that supplies compressed air (and natural gas, water, drains, etc) for tradeshows, conventions, and events here in Las Vegas.  They size their compressors to the demand of the total cfm for the show, and that's the formula they use (straight out of the Master Plumbers' books).

   You are right about the part of your post concerning the rating of the compressors.  They list the total continuous running CFM, and not demand.  Most of us will not use enough CFM to make our compressor run continuously. 

   Hope this helps.

   Len (Len's Custom Woodworking)

1. 
   riverr1 | Sep 10, 2002 09:54pm | #14

   Len,

   Smart alec? Never entered my mind. Where Im coming from was in needing a compressor that would run my Sharpes HVLP with a gallon pot. I needed a minimum of a constant 14 cfm or I couldn't get the right spray pattern. I also like using a pnuematic ROS that also sucks the air. That 4 cfm per hp is a new one to me. I did a lot of studying before buying my compressor and never came across that.

   Don

1. 
   LRutherfor1 | Sep 11, 2002 03:26am | #15

   No problem.  I use a Craftsman, 5.5 HP 30 gallon (verticle) for my shop, and I've never run out of air yet.  I do use my sprayer on it.

   Len (Len's Custom Woodworking)

8. 
   CRAIGCONEY_M | Sep 10, 2002 06:35pm | #10

   Steve,

   Take the time to analyze what you really want to do with your compressor before you buy.  I boutght a PC 3hp 4 gal pancake, with using it for nailing/stapling and some jobsite considerations, plus doing some 'very' conservative spray finishing in mind- mostly small projects using a small gun.

   Yes, its oil-less and loud, but the induction motor is much quieter that the univeral motor models.  But then again, is shtere really a 'quiet' air-compressor? 

   2 months after purchasing the unit, I found out that I needed to finish kitchen cabinets that I was building.  So, after some research, and deciding on an HVLP gun, my pancake doesn't supply what is realy required for spraying with a larger gun.  (My neighbor is graciously allowing me to use his HVLP system in the meantime.)

   If you can afford the extra space, extra money, and do not require portablitlity, go for the bigger unit by all means.   

   Craig

1. 
   riverr1 | Sep 10, 2002 06:44pm | #11

   Craig,

   I know a muralist that picked up a Binks gun and 1 qt. pot that works on low cfm for small compressors. Of course for the price of the set up you can get a nice compressor! 6 of 1, half a dozen of the other!

   Don