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Thread: Gravity Gun Cup Leaking

  1. #1
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    Gravity Gun Cup Leaking

    I'm getting my feet wet with spraying in preparation for a bunch of small projects for Christmas presents. I have a big 2-stage compressor, so I decided to go with a cheap HVLP conversion gun to start. I got the one from Harbor Freight that seems to have good reviews there and on Amazon. It seems to be working well except I'm getting leaks where the cup screws onto the top of the gun. Should there be any type of sealant or gasket on that connection?

  2. #2
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    Make sure the mating surfaces are clean. If it still won't seal when tightened by hand then put some Teflon tape on the threads.

    And, yes, the purple HF gun that you can often buy on sale for $10 sprays low viscosity materials very well.

    John

  3. #3
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    If it leaks, it needs thread sealant at least. Ordinary Teflon thread tape works. Cheers

  4. #4
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    Thanks, I wasn't sure if it was ok to use sealant or not on those threads. I'll try that tomorrow. I'll be spraying General Finishes waterborne poly mainly.

  5. #5
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    You will need to thin any of them in order to spray them well through that 1.4 mm N/N. How much depends upon which product you want to use. The best approach is to get yourself a cheap #4 Ford cup and use that to determine how much you need to thin them to get the viscosity down below 40 seconds, preferably around 25.

    John

  6. #6
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    Not to diverge, but... John, would that gun be well suited to spraying water soluble dye? "Enquiring minds want to know..."
    --

    The most expensive tool is the one you buy "cheaply" and often...

  7. #7
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    Quote Originally Posted by Jim Becker View Post
    Not to diverge, but... John, would that gun be well suited to spraying water soluble dye? "Enquiring minds want to know..."

    Yes, the purple HF gun with a 1.4 mm N/N sprays water or alcohol based dyes very well, and Sealcoat shellac, too.

    John

  8. #8
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    Thanks, John...I've been meaning to ask and the OP's thread jogged my memory, especially when you got into the viscosity thing. I need to move to spraying the dye on my tack trunk commissions for better results. We now return you to your regularly scheduled thread...
    --

    The most expensive tool is the one you buy "cheaply" and often...

  9. #9
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    I was spraying straight denatured alcohol as a test last night and it worked great other than the leak. The pattern and atomization seemed fine.

  10. #10
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    Jason, I wonder if the threads are buggered? I'd try the tape or maybe a thick o-ring if the cup tightens down far enough to seat against one.
    --

    The most expensive tool is the one you buy "cheaply" and often...

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