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Thread: "Shoebox" compressor problem...

  1. #1
    Administrator AirGunEric's Avatar
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    "Shoebox" compressor problem...

    Anyone maybe have an idea what is going on with a/this Shoebox compressor;

    3000psi model, the lock ring for the rod/spring actuator to disengage the motor when set pressure is reached has been set for 3300psi (i.e. as far out on the rod as it will reach)- and it is still sitting there, but compressor/motor is cutting out at 2000psi.

    Last time it was used a few weeks ago- it was working A-Ok at 3300psi and has only sat since yesterday when this developed.

    Anyone have any knowledge or idea why this would occur? (compressor is not exactly "heavily used")
    I'd say I care- but I'd probably be lying...


  2. #2
    Moderator rsterne's Avatar
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    Likely an O-ring starting to go.... I have to replace one about every 75 hours.... Post on the ShoeBox forum and you will get an answer quickly about where to look....

    Bob
    Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
    Airsonal: Too many to count!

  3. #3
    Administrator AirGunEric's Avatar
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    Well- funny enough- I've had it for just under 2 years- but it probably only has about 75 hours of run-time on it (don't get anywhere near as much shooting done as I'd like). Maybe it's time to strip the whole thing down and clean it up.
    I'd say I care- but I'd probably be lying...


  4. #4
    Moderator rsterne's Avatar
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    I found the inner high pressure O-ring (lower cylinder, second one in) is usually the culprit.... First time I rebuilt mine I just swapped the inner and outer and got another 75 hours.... second time I replaced them both.... still going....

    There is an excellent video on the website explaining how to rebuild the ShoeBox.... dead simple....

    Bob
    Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
    Airsonal: Too many to count!

  5. #5
    Administrator AirGunEric's Avatar
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    Going through things (the forum posts and the online videos) any idea why lithium grease is used on all the o-rings instead of silicone grease?
    I'd say I care- but I'd probably be lying...


  6. #6
    Moderator rsterne's Avatar
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    I don't know why.... but I DO know what I use.... and in fact I'm kind of running a "trial" for Tom with it.... I use Texaco Molytex EP2 Grease (contains a small % of Moly).... I asked Tom if the flash point was high enough, and he said it should be fine.... I have been using it for over 200 hours with no problems.... The first grease I used was a "bio-based" Lithium which was a DISASTER and resulted in the machine siezing up after only a few hours.... and a warning being posted about it on the ShoeBox Forum....

    Bob
    Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
    Airsonal: Too many to count!

  7. #7
    Administrator AirGunEric's Avatar
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    What is the minimum flash point he wanted to see to keep things from getting explosive?

    I really have never liked lithium greases...
    I'd say I care- but I'd probably be lying...


  8. #8
    Moderator rsterne's Avatar
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    Can't remember.... best to PM Tom....

    Bob
    Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
    Airsonal: Too many to count!

  9. #9
    Senior Member SeanMP's Avatar
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    You might try this as an alternative

    http://l-36.com/superlube.php

    it has a higher flash than lithium and lower coefficient.

    I use it almost exclusively for the triple stage compressors on the ship.

    And it's food grade Oring compatible
    Sean

  10. #10
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    I believe it is stated on the shoebox forum that lithium grease is recommended because it stays on longer that silicone grease.

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