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Thread: How does this Crush Washer work?

  1. #21
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    I have not used a crush washer yet that would crush. If you need another 1/4 turn or more you're outta luck in my experience..... I like to be light-handed torque-wise on these and don't like to just turn it on harder to get there. I always wind up calculating how much of a turn I need and what that translates to in washer thickness, then I surface grind the washer until I get the indexing I want at the lightish torque I want. I don't have a spec but I'm gonna guess I go 15 foot pounds or less (just going by memory here, I think my Yamaha DT3 called for 25 ft-lbs on the spark plugs and I don't go that tight on FH's).

  2. #22
    cebuboy Guest

    Question

    Quote Originally Posted by AR15barrels View Post
    The "military silver aluminum crush washer" is NOT a crush washer.
    It's a peel washer.
    You heat it up with a lighter and it delaminates into MANY layers.
    Then you "peel" away as many shims as you need to so that the muzzle device torques into proper alignment.
    How hot should I heat the peel washer? I busted my lighter heating it and it still did not delaminate, it just turned yellowish white.

  3. #23
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    Quote Originally Posted by cebuboy View Post
    How hot should I heat the peel washer? I busted my lighter heating it and it still did not delaminate, it just turned yellowish white.
    Forget the lighter. I've had peels that didn't do anything when heated too. Just get a sharp razor blade and be careful not to slice your fingers.
    "You people have too much time on your hands." - scottryan

  4. #24
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    Quote Originally Posted by demigod View Post
    Forget the lighter. I've had peels that didn't do anything when heated too. Just get a sharp razor blade and be careful not to slice your fingers.
    One side of the peel washer is a solid washer.
    That part won't delaminate no matter how hot you get it.
    The other side will though.
    Pliers and a torch is where it's at.
    Randall Rausch
    AR15 Barrel Guru
    California Precision Rifle Club founding member

  5. #25
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    For using crush washer what I do is that I have about 7-8 crush washers on my work bench and keep trying one until I find one that'll allow the FS'r to align without more than about 20ft lbs.

    For peel washers I either use a utility knife and a small set of pliers or put a peel washer on a piece of wire hanger and heat it really hot with a propane torch to get it to come apart.
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

  6. #26
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    Quote Originally Posted by AR15barrels View Post
    One side of the peel washer is a solid washer.
    That part won't delaminate no matter how hot you get it.
    The other side will though.
    Pliers and a torch is where it's at.
    Hmmm.. I've never tried torching the poor thing.

    I haven't done more than 3 or 4... so I just slice the sucker out of impatience.
    "You people have too much time on your hands." - scottryan

  7. #27
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    Quote Originally Posted by gotm4 View Post
    For using crush washer what I do is that I have about 7-8 crush washers on my work bench and keep trying one until I find one that'll allow the FS'r to align without more than about 20ft lbs.
    Re using a crush washer.
    You know you're not supposed to do that.

    I do it too and I (like you) know when you can and when you can't re-use a crush washer.
    I also have a big collection of used crush washers to try.
    If they are all too thin, I grab a new one and crush it as required.
    Randall Rausch
    AR15 Barrel Guru
    California Precision Rifle Club founding member

  8. #28
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    Crush washers are machined from 302 stainless steel. As with any grade of steel this can exist in a multitude of heat treatment conditions and as such all crush washers are not equal. The best I have found are from YHM. These seem to be the softest to work with.

    While we are discussing crush washers we should also consider the installation. The washer was designed to install with the bevel against the barrel (the opposite of how they are commonly fitted). This allows the washers to compress much more easily but the flash hider is now pulled up against the smallest diameter of the washer and if the threads are not well formed in both parts the flash hiders can cant slightly. To elleviate this problem the washers are commonly reversed but this will increase the installation force for equivalent displacement.

    One trick that can be applied in installing the washers is to measure out the amount of rotation that is required to index the flash hider and then use an old barrel stub to precrush the washer to just below what is needed. This way it is possible to adjust the intallation torque to suit.

    Peel washers are a convenient way of indexing a flash hider and are the item of chioce if the axial alignment is critical such as a QD silencer mount. They are typically 316 stainless and are laminated with a phenolic resin. This allows a washer to operate at temperatures up to 250 and the resin should not degrade until +500. Installed washers that are subject to heating above this will not relax substantially but the washers should not be heated to temperatures that cause delamination prior to installation. A sharp knife is the prefered way to remove laminates.

    If available the best method to index a flash hider remains a machined shim. Turned from bar stock these are surface ground to provide the exact thickness required. Beyond match rifles the availability of peel washers renders this method overly intricate.

    Bill Alexander

  9. #29
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    Good info!

    Now that I think of it... My last three FH installs have been AAC Fast attach flash hider/mounts which require NO indexing or washer of any kind.... similar to the Smith Arms Vortex install.
    "You people have too much time on your hands." - scottryan

  10. #30
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    Question CRUSH WASHER HELP!!

    Simply stated which direction does the crush washer face when installing the flash hider? Concave to the threads of the barrel, with the pointed side to the flash hider or the other way?

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