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Thread: Another compressor/nail gun question

  1. #1

    Another compressor/nail gun question

    Hello,

    Even though I am a newbie when it comes to nail guns and compressors, I thought that I understood how my new Porter-Cable FN200C nail gun and Craftsman 3 gallon 1 HP compressor was supposed to operate.

    Hereís my question:

    Before I begin, let me assure you that EVERYTHING was correctly set up. Even though Iím a newbie in this area, I know how to set this stuff up.

    Here goes.

    When I start up the compressor, it builds up pressure to 125 psi on the tank gauge, then it cuts off. I set the regulator gauge on the output side to 70 psi, then I begin to nail 2 inch finish nails.

    After I nail about seven or eight of them, I notice that the tank pressure is down to 100 psi, but the regulator pressure is now BELOW 70 psi (the place where I initially set it).

    My question is, WHY, if the tank pressure is still above 70 psi, has the output pressure dropped? I assumed that the output pressure would never have to be reset. I understand that as I use the nail gun, I am using up part of the pressure in the tank and therefore the tank pressure will show a lower pressure than the initial reading, but
    I thought that as long as the tank still had at least as much pressure as the regulator setting, it would not require me to reset anything.

    Surely, I am not supposed to have to continually reset the regulator pressure as the tank depletes.

    What am I missing?

    Thanks,
    Louis

  2. #2
    Join Date
    Nov 2006
    Location
    Little Rock, AR.
    Posts
    642
    There is a range of pressure between where the regulator will relieve to and where it will build to. When you started the compressor up, it sounds like you allowed the hose end to build to a pressure higher than 70psi, and adjusted the regulator until it relieved down to 70. Then as you dumped pressure using the nail gun the regulator allowed the pressure to build back. You approached the pressure setting from two different directions - doing so will often not yield the same result. Also there is "some" proportionality to the setting - a setting of 70 in front of a tank pressure of 125 may often yield a reading of 69 or so at a tank pressure of 90. It takes a very precise (read this to mean high dollar) regulator to overcome this - but usually it is within a range not noticed by most tools.
    The opinion of 10,000 men is of no value if none of them know anything about the subject.
    - Marcus Aurelius ---------------------------------------- -------------

  3. #3
    Join Date
    Jul 2008
    Location
    Central Ky.
    Posts
    153
    Louis, I usually set my regulator while using a small blow gun. Also my nailer manuals specify 90 psi so thats what I use, LOL, Craig

  4. #4
    Join Date
    Jun 2007
    Location
    Newburyport MA
    Posts
    294
    Louis

    After the compressor shuts off, try dialing the pressure to below 70 and then back up to 70. I am not familiar with your set up but that seems like an awfully quick drop off in pressure.

    Bob

  5. #5
    Join Date
    Nov 2006
    Location
    N.E. Ohio
    Posts
    4,104
    Hello,
    How much hose are you running?

    The same thing happens to me when I run 50' of hose or more.

    I added a 10' long 1/4" whip end w/a regulator between the whip end and the main hose.
    Also - for long runs of hose - 100' or more - I stick a 5 gal aux tank at the end of the hose and run the whip end on the off side of the tank.

    A decent regulator can be had for around $20.00 or so.

    The ones from HF will work, but,being HF - the actual settings on the regulator may or may not match the actual air pressure.

    BTW - 70psi is a bit on the low side. I usually run 75 to 80 psi. on my PC nailers. I found the results were more consistant.
    PC makes a decent nailer, just not as efficient as others in that same price range.

    The only gun I run @ 70 psi is my Bostitch framing nailer.
    Any more psi in that beast & it blows 3 1/2" nails almost halfway into a 2x4.
    try to remember that the very first step in finishing a project is choosing the material. You want to select wood that has the color and grain pattern than best suits your requirements as "covering up" those things after the fact makes your work much, much harder - Jim Becker

  6. #6
    I'm running 25 feet of 1/4 inch hose.
    Louis

  7. #7
    I think that I'm ok now. I've continued to work with it, and now the regulator pressure seems to be holding steady. Thanks for your help.
    Louis

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