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Buying a compressor, need help!

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  • Buying a compressor, need help!

    Can anyone help me? Buying a compressor and I am looking at the Ridgid OF45150(compressor alone $398) and the PC CFFC350C (which is the compressor and framing nailer $499) There appears to be 2 different readings on the Ridgid OF45150 twin stack compressor. At and on the actual box and machine the ouput reads 4.9 SCFM@90PSI but at the official RIDGID site and on many reviews it reads 6.2 SCFM. Does anyone own this machine? What is the actual output? It is just for home use (ie. some home reno and wheel rotation) Compressor wise will I really notice a difference? Or are things like tank size and the small approx. 1 scfm difference much of an issue for occasional user?

  • #2
    Hi petjat,

    Welcome to the forum.

    I am not an expert on compressors, but here is what little I know. You need to decide what your basic use for it will be as well as any limitations it may have. For instance, if you do nothing but use it for air nailing, flow is not important. Air nailers use it for the pressure to hammer in the nail. If you use it for painting, another story altogether. Spray guns (paint sprayers) will say what flow at what pressure they recommend.

    The SCFM will vary with pressure, generally speaking. The higher the pressure, the more flow.

    Tank size also is somewhat dependent on what you do. If you plan on using it for the air nailers, one of these "pancake" compressors offer sufficient volume and because of the smaller tank, more portability. If you plan on spray painting, the bigger tank will be necessary. Obviously, the bigger tank will also affect how often the compressor has to come on and go off so some wear and tear factors come into play there.

    Hope this helps.

    It is impossible to make anything foolproof because fools are so ingenious.


    • #3
      Don't have a real clue as to why the difference in the ratings. That being said, hows this for a WAG? While the Ridgid US website rates the compressor in SCFM(Standard Cubic Feet per Minute), maybe the Canadian website and the export packaging rate the compressor in SCMM(Standard Cubic Meters per Minute).
      I decided to change calling the bathroom the "John" and renamed it the "Jim". I feel so much better saying I went to the Jim this morning.


      • #4
        Your compressor needs to be sized for the use. If you are going to be using rotary air tools, like a DA sander, grinder, etc. where you need continuous air flow, you will need close to 7 CFM at 90 psi with at least a 20 gal tank minimum. I have a Campbell-Hausfeld Extreme duty 5HP with a 26 Gal tank and a cast iron compressor (rated at 6.8 SCFM at 90 psi). I have painted houses with a traditional spray gun/pressure pot set up, and used it to sand boats for bottom painting with a DA (dual action) sander and it met the job. I burned up two Craftsmen 3 HP with 10 gal tanks (got them cheap) before I bought the current compressor. I had to continually wait for the compressor to catch up, and both were extremely noisy. The cast iron compressor will be much quieter than an aluminum one if that is a concern. One drawback to my current compressor is that it is heavy (about 350 lb). Its okay if you have a low trailer, but its a bear to get into the back of a pick-up, even with ramps.
        Another tip: buy 3/8 ID air hose instead of 1/4" if you are doing anything more than changing tires. You will lose a lot of air volume (and that leads to lower pressure) with anything more than 10' of 1/4" hose. A 1/4" ID hose can't carry enough air to meet the demands of most air tools for more than a few seconds.
        Practicing at practical wood working


        • #5
          I bought the pancake combo pack the porter cable put out back when it only came with two nail guns for about $300, and it worked great, but as the others stated it limits what you can do, when I decided to buy an HVLP sprayer, I bought this one, HUSKY
          5.5 Peak / 1.7 Running HP, 26 Gallon Husky Compressor, Model WL6507, Price: $259.00/ea

          I like it because it stores falt and one it's end, it is easy to load in the back of my truck by my self when I need to, not that often. And I can either run hose from it into the house or take the pancake one in if I need to work inside.
          Last edited by kdurhamjr; 02-12-2006, 11:38 AM.


          • #6
            Both readings are correct. Manufacturers usually put a SCFM @ 40 psi and 90 psi. AFAIK the 40 psi rating is always a higher number. Depending on what you plan to do with it you need to consider those numbers. If your spraying (approx. 40psi) you will want a larger tank, but can get by with a high SCFM and a smaller tank. If you are just shooting guns you will want to look at the SCFM @ 90psi.

            Knowing your SCFM ratings on your compressor will help when it comes to buy tools for it. Most tools list a required minimum SCFM on the box, or on the tool.


            • #7
              As previously stated, compressor capacities are usually stated as flow (volume) in Standard Cubic Feet/Minute (scfm) at both 40 psi and 90 psi. These two numbers are indicative of maximum that the compressor will handle and therefore the limiting parameters that an air-tool application needs to consider.

              The second parameter that needs to be taken into consideration, is the size of the tank which stores the pressurized air. Tools like nailers require a single high-pressure shot of air to operate tool's mechanism. Therefore something like a "pancake" compressor works very well. These tools usually require something in the neighborhood of 90 psi at only about 1 or 2 scfm.

              Mid-use tools like impact wrenches, drivers, etc. will require more air to operate thier rotation or spin and will therefore require more volume. Typically, you'll find this type of air tool requiring 5 to 7 scfm at 90 psi. This would be a bit much for the typical pancake compressor, because they simply don't have the volume and the small tank would provide no reserve should you drive a bolt or nut for more than a few seconds.

              Larger volume applications like spray finishing, sanding and other fairlly continuous tool operations require good volume that can be maintained with consistant pressure. For instance, a "finish" type spray gun will require at least 10 scfm at 40 psi or more. In such applications, you need a compressor that not only has good displacement, but also one which has a fairly good sized tank.

              So, the bottom line is that your tool/application is the driving factor in selecting any compressor. If you feel that your only needs will be to drive a single nailer, inflate your tires, or drive an impact wrench, then the Ridgid would be fine. If you forget about the impact wrench, you could get by with just a pancake compressor. But if you look "down the road" and feel that you might want to get into other shop uses and/or doing some painting or varnishing with a spray gun, then you'll need to consider getting a larger compressor. (Although a smaller gun, like a "spotting" or touch-up gun requires substantially less volume.)

              A couple other things that need to be considered. Generally speaking, lubricated (oil in the crankcase that is also used to lube the cylinders) compressors usually will last longer than non-lubricated (NL) compressors. NL compressors use teflon rings and bearings or similar 'dry' methods to lubricate.) Similarly, cast iron compressors will last longer than aluminum. For most home uses, aluminum is used for non-lubricated, high RPM compressors. Cast iron units are usually lubricated, lower rpm, and used in mid-price range designs. Although there is some overlap in price, the cast-iron units are more often used in stationary designs, with larger tanks. Cast iron, lubricated compressors are usually less noisy. There are of course, cast iron, NL units, but these are mostly commercial grade. In such cases, the running gear is oil-lubricated, and the cylinders NL with special cylinder liners and/or teflon-like piston rings, wear bands, or whatever.

              I hope this helps,



              • #8
                Oil less or oil lube

                Not sure which one you are looking into, but a colleague has the oil less twin stack and it has enough air to power two framing nailers easy.

                *****The downside*******
                Although lots of power for the nail guns, this unit is considerably louder than an oil lube and it is a power hog on the circuit breaker. Wouldn't run this on an extension cord.
                Last edited by tkholck; 04-08-2006, 02:55 AM.


                • #9
                  OF45150 SCFM Rated flow @ 90 psi

                  FYI: I was getting ready to pick up one of these compressors and also noticed the the spec for 90 PSI changed (was 6.2 SCFM @ 90 psi, now its 4.9 SCFM@90 psi).

                  Was the higher number a typo, or did they change the compressor (or the way it was rated)??


                  • #10
                    I think the difference is the Home Depot rating should have been 6.2 at 40scfm the cfms are always higher at 40 and I believe that is the difference