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Thread: Romanian '3' Front Trunion

  1. #11
    Indian Admin Winn R's Avatar
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    Quote Originally Posted by Tommo View Post
    It is easy to push a standard size Romanian barrel into it with light finger pressure. .
    It's barely an interference fit to begin with -- the chamber end has a taper so starting is not a problem. The tape can be coated with an anti seize. I've got an old thread here somewhere, I'll see if I can find it.

    Edit -- couldn't find that one but did run across another way of handling the same problem.

    http://www.gunco.net/forums/f163/epo...ounting-39748/

    It's still working fine after all these years. It's the method used now to hold in barrel liners.
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  2. #12
    GuncoHolic Tommo's Avatar
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    Thank you very much for all the information!

    Might try knurling the chamber end of the barrel. I am worried about using aluminum tape or epoxy. Could the tape melt or the bond of the epoxy break-down from the heat?

  3. #13
    No Hope For Me 1biggun's Avatar
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    Could the tape melt or the bond of the epoxy break-down from the heat?
    YES

    IMO ITS BETTER TO HAVE STEEL TO STEEL CONTACT . THE BARREL HAS TO COOL THE BETTER THE FIT IS TO THE TRUNION THE MORE HEAT WILL TRANSFER TOT THE TRUNION KEPPING IT COOLER LONGER AN ALLOWING IT TO COOL FASTER .

    ID THINK AN EPOXY WOULD WORK LIKE AN INSULATER .

    THESE GUNS ARE NOW WORTH $500 - $1000+ WHEN BUILT RIGTH NOW IS NOT THE TIME TO DO A COBBLED BUILD.

    THE FIRST HING YOU NEED TO DO IS FIGURE OUT HOW MUCH CLERANCE YOU HAVE . YOU NEED TO KNOW WHAT THE ID OF THE TRUNNION IS AN THE OD OF THE BARREL BEFORE YOU CAN MAKE ANY DECISION.. IF IT GOES TOGETHER BY HAND THATS PRETTY DAMN LOOSE . I KNUREL BARRELS WHEN THEY PRESS FIT TO LOOSE OR A MALLET CAN BE USED TO GET IT IN. YOU CANT MAKE ANY DECISION UNTIL YOU KNOW YOUR SPECS.

    IF YOU KNURLYOU NEED TO USE A PATTERNTHAT IS GOING TO GIVE YOU AS MUCH CONTACT AS POSSABLE . A HEAVY LARGE PATTERN WILL GIVE MORE OD TOTHE PART BUT YOUR GOING TO LOOSE CONTACT . A SMALL PATTERN WILL GIVE LOTS OF CONTACT BUT YOUR PART STILL MIGT NOT BE TIGHT ENOUGH.

    YOU CAN ALSO LIKELY TURN IT TO AROUND 19MM AN MAKE A SLEAVE THAT FITS CORRECTLY.

    I DONT SEE HOW TAPE WILL GET IN THERE UNLESS ITS REALLY LOOSE AN IM NOT SURE HOW WELL ALUMINUM WILL HOLD UP ON VIBRATING BARREL THAT HEATS UP AN COOLS DOWN.

    IM SURE THERE ARE GUYS HERE WHO CAN KNURL IT FOR YOU FOR VERY LITTEL . ITS A EASY JOB AT ANY MACHINE SHOP SHOULD TAKE ABOUT 15 MINUTES .

  4. #14
    GuncoHolic Sprat's Avatar
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    I think big gun is right the solder would tend to lossen over time with trunnion and barrel, steel to steel is best

    barrel liners do hold and are a great solution when relining the whole barrel and distubting the heat and i could even see using this method for the front site or gas block as winnR stated

    tape i don't know, if it were way out then maybe a collar around the barrel end but the tolernances are to tight here
    Sprat and sprat1 are one and the same.

  5. #15
    Gunco Rookie Hueto's Avatar
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    Anybody have any figures for the maximum discrepancy that has been successfully overcome with knurling? My #3 trunnion's journal measures in at .910"-.913", and my M70 barrel (#3) is between .906"-.907".

    After reading all of AKBlue's advise both here and on the Files, I just ordered the Enco hand tool. We'll see what happens.

    I played around with a center punch, and after about a minute or two of stippling, I increased the tension enough that the trunnion will now stay on by itself if I hold it upside down. Haha, that's good right?
    Last edited by Hueto; 04-10-2013 at 04:16 PM. Reason: typo

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    Gunco Regular akblue's Avatar
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    I do not know the nominal diameter increase you can achineve with the knurling tool. It is substantial. As you rotate the tool 360 degrees a couple of revolutions you tighten the knurling wheel and then turn again in the same spot. This raises the knurled area diameter more each time. Far more coverage and uniformity than hand knurling., particularly when the diameter gain required us large.
    Last edited by akblue; 04-10-2013 at 07:24 PM.

  7. #17
    No Hope For Me 1biggun's Avatar
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    Anybody have any figures for the maximum discrepancy that has been successfully overcome with knurling? My #3 trunnion's journal measures in at .910"-.913", and my M70 barrel (#3) is between .906"-.907".

    After reading all of AKBlue's advise both here and on the Files, I just ordered the Enco hand tool. We'll see what happens.

    I played around with a center punch, and after about a minute or two of stippling, I increased the tension enough that the trunnion will now stay on by itself if I hold it upside down. Haha, that's good right?
    hMMMMM you need a better tool to meaure with if you cant tell with ina .003" range what you have.

    you will want a about .0015 interference with a knurled set up . if tis not knurled a little less will work I like .001 for a barrel im making my self.

    The part needs to press on fairly tight if it dosent it will wear an get looser.

  8. #18
    Gunco Member ak mastertech's Avatar
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    Here is a bit of insight into the process and what a correct pattern looks like
    http://r-mceachern.com/data/edu/Curr...0standards.pdf[/

    In a condition where knurling is used, Less than half of the surface area of the barrel journal may be in contact with the trunnion ID, not a 100% interference fit.

  9. #19
    White Cracker 4thIDvet's Avatar
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    Most or some Romanian barrels should have 4 numbers on the top of the barrel, toward the back.
    Why? Smart thrifty people over there.. In America, if a building tool requiring very tight tolerances wears, we heave it..
    To save money during the cold war years, nothing was heaved..
    Not a machinist so bare with me here.. As the tool wore, tolerances changed ever so slightly.. Holes became smaller with wear..
    Frist number should represent front sight.
    Second. Gas port fixture.
    Third. Rear sight.
    Fourth. Trunion..
    As a part was needed to complete the weapon, workers would go to say, barrel 4 for the correct trunion..
    If they drank to much vodka the night before, they did not give a damn..
    That is why de-milling some Romanians, you need a bulldozer to get the barrel out.. Lite sanding and lube to get it back in.. Or vise versa, loose fit..
    Look at your Romanian barrel, you should see the 4 numbers..

    The BIG Guide To Romanian AK Variants And Accessories! - Weapons Cache Forums
    Go too "Other Markings" about a third of the way down the page..
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  10. #20
    Gunco Addicted for life j427x's Avatar
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    Quote Originally Posted by 4thIDvet View Post
    Most or some Romanian barrels should have 4 numbers on the top of the barrel, toward the back.
    Why? Smart thrifty people over there.. In America, if a building tool requiring very tight tolerances wears, we heave it..
    To save money during the cold war years, nothing was heaved..
    Not a machinist so bare with me here.. As the tool wore, tolerances changed ever so slightly.. Holes became smaller with wear..
    Frist number should represent front sight.
    Second. Gas port fixture.
    Third. Rear sight.
    Fourth. Trunion..
    As a part was needed to complete the weapon, workers would go to say, barrel 4 for the correct trunion..
    If they drank to much vodka the night before, they did not give a damn..
    That is why de-milling some Romanians, you need a bulldozer to get the barrel out.. Lite sanding and lube to get it back in.. Or vise versa, loose fit..
    Look at your Romanian barrel, you should see the 4 numbers..

    The BIG Guide To Romanian AK Variants And Accessories! - Weapons Cache Forums
    Go too "Other Markings" about a third of the way down the page..

    that is the way it was-- if you ran too much scrap you ended with a real job on a work farm on some gulag--

    if you made 500 working ak a day you got a bowl of turnip soup!

    socialism --you got to love it!

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