What welder for pin/weld of barrels?

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Replies

  • BigDanSBigDanS Senior Member Posts: 6,797 Senior Member
    JasonMPD wrote: »
    We want to offer it as a service ultimately. And it's a skill I've wanted to dabble in for some time anyhow.

    The "pin and weld" method of compliance is industry accepted. Daniel Defense pins and welds their muzzle devices for the 16" OAL compliance.

    My plan, if all goes well, is to use an appropriate size inexpensive endmill to do a very shallow plunge cut into the barrel using the drilled hole in the muzzle device as a pilot. This will create a cylindrical hole and if the pin I make is cut squarely, when the pin sits in the divot it will be squarely sitting in the divot...no taper on the pin or divot due to a typical drill bit. Harder to shear with a long wrench.

    Sent from my SAMSUNG-SM-N910A using Tapatalk

    Of course, to avoid BATFE non-sense and the variability of tools, measuring devices, etc., my opinion is it should be 16.25"

    D
    "A patriot is mocked, scorned and hated; yet when his cause succeeds, all men will join him, for then it costs nothing to be a patriot." Mark Twain
    Alcohol, Tobacco, Firearms and Explosives.... now who's bringing the hot wings? :jester:
  • tennmiketennmike Senior Member Posts: 25,957 Senior Member
    While silver soldering would work, the barrel/brake has to be pretty dammed screaming hot to make a good silver solder joint. Know what happens when you heat carbon steel screaming hot and then let it cool? It RUSTS within an hour, and in high humidity like FL, probably less time. If you think oiling it down after silver soldering will stop the rust, you're wrong. The steel pores already opened up during heating and the rust started before you even started soldering. The heat accelerated the rusting process.

    Silver solder takes a temperature of the parts to be soldered to be heated to over 570° F for the solder to flow and get a good solder joint. That happens to also be the general temperature for tempering steel at the low end, and a temperature that can weaken already tempered steel parts. And unless the entire threaded portion of barrel and brake are coated with the solder, the rust will go to town on those unprotected bare steel surfaces. And you can't see it.

    Silver solder has it's place, but this ain't it.

    TIG welding the pin and a couple of spot welds at the back of the brake is localized heat that dissipates quickly. And a little penetrating oil like Kroil on the back of the brake and at the barrel muzzle after welding will wet down the threads and head off thread rusting. And FWIW, a MIG welder won't give you the fine control needed for welding the relatively small areas of the brake and require MUCH LESS cleanup. TIG is the best choice for the job.
    Do not meddle in the affairs of dragons, for you are crunchy and taste good with ketchup.


  • TeachTeach Senior Member Posts: 18,345 Senior Member
    Mike, I realized a long time ago that someone who has his mind made up doesn't want to be confused with facts! Experience is a great teacher, but the lessons tend to be on the expensive side!
    Jerry
    Hide and wail in terror, Eloi- - - -We Morlocks are on the hunt!
    ASK-HOLE Someone who asks for advice and always does something opposite
  • JasonMPDJasonMPD Senior Member Posts: 6,104 Senior Member
    Teach wrote: »
    Mike, I realized a long time ago that someone who has his mind made up doesn't want to be confused with facts! Experience is a great teacher, but the lessons tend to be on the expensive side!
    Jerry
    My mind's not made up yet...



    Sent from my SAMSUNG-SM-N910A using Tapatalk
    “There are three kinds of men. The one that learns by reading. The few who learn by observation. The rest of them have to pee on the electric fence for themselves.” – Will Rogers
  • JasonMPDJasonMPD Senior Member Posts: 6,104 Senior Member
    And I have not had any inclination to use silver solder. I don't have a desire to drastically heat up the entire barrel like that.

    Sent from my SAMSUNG-SM-N910A using Tapatalk
    “There are three kinds of men. The one that learns by reading. The few who learn by observation. The rest of them have to pee on the electric fence for themselves.” – Will Rogers
  • BigDanSBigDanS Senior Member Posts: 6,797 Senior Member
    tennmike wrote: »
    While silver soldering would work, the barrel/brake has to be pretty dammed screaming hot to make a good silver solder joint. Know what happens when you heat carbon steel screaming hot and then let it cool? It RUSTS within an hour, and in high humidity like FL, probably less time. If you think oiling it down after silver soldering will stop the rust, you're wrong. The steel pores already opened up during heating and the rust started before you even started soldering. The heat accelerated the rusting process.

    Silver solder takes a temperature of the parts to be soldered to be heated to over 570° F for the solder to flow and get a good solder joint. That happens to also be the general temperature for tempering steel at the low end, and a temperature that can weaken already tempered steel parts. And unless the entire threaded portion of barrel and brake are coated with the solder, the rust will go to town on those unprotected bare steel surfaces. And you can't see it.

    Silver solder has it's place, but this ain't it.

    TIG welding the pin and a couple of spot welds at the back of the brake is localized heat that dissipates quickly. And a little penetrating oil like Kroil on the back of the brake and at the barrel muzzle after welding will wet down the threads and head off thread rusting. And FWIW, a MIG welder won't give you the fine control needed for welding the relatively small areas of the brake and require MUCH LESS cleanup. TIG is the best choice for the job.

    Isn't it just the top of the pin welded / soldered, so the pin cannot be removed from the brake? My understanding is a tiny pinpoint torch could heat it and get the solder over it. I suppose you could drill the hole size in the brake slightly big and use some flux to get the silver solder into the space and make a joint with more connection.

    Regarding heat and oxidation, TIG is over 11,000 F for a short period. That's hot! I understand it is only at the point of the weld but the surrounding metal has to get hot enough to temper some.

    I don't believe there is a free lunch. TANSTAAFL


    D
    "A patriot is mocked, scorned and hated; yet when his cause succeeds, all men will join him, for then it costs nothing to be a patriot." Mark Twain
    Alcohol, Tobacco, Firearms and Explosives.... now who's bringing the hot wings? :jester:
  • JasonMPDJasonMPD Senior Member Posts: 6,104 Senior Member
    cpj wrote: »
    Of course the easy solution is use a 16" barrel, and don't worry about that extra 1.5-2" worth of brake.
    Because it doesn't make one bit of difference in the real world.
    Indeed.

    But customers have money and they want to part with it for various reasons I desire to accommodate.

    Sent from my SAMSUNG-SM-N910A using Tapatalk
    “There are three kinds of men. The one that learns by reading. The few who learn by observation. The rest of them have to pee on the electric fence for themselves.” – Will Rogers
  • RocketmanRocketman Banned Posts: 1,118 Senior Member
    So where are these "check sites" and BATFE workers with tape measures? I'm sure its happened to some poor bastard before. But how often does Joe Average get screwed for barely being under 16 IF he's not doing something obviously illegal like robbing a store?
  • coolgunguycoolgunguy Senior Member Posts: 6,413 Senior Member
    JasonMPD wrote: »
    Indeed.

    But customers have money and they want to part with it for various reasons I desire to accommodate.

    Sent from my SAMSUNG-SM-N910A using Tapatalk


    I have no problem with that! :up:

    I do have to ask, why fuss with the pin at all? If the plan is to fill a 'need', and the pin is unnecessary, why bother with it at all? We've all heard the stories of how the pin was insufficient and sheared under 'testing', so other than being able to say the barrel is pinned, I just don't see the allure. :uhm:
    "Bipartisan" usually means that a bigger than normal deception is happening.
    George Carlin
  • jaywaptijaywapti Senior Member Posts: 4,506 Senior Member
    [QUOTE=BigDanS;597014 Regarding heat and oxidation, TIG is over 11,000 F for a short period. That's hot! I understand it is only at the point of the weld but the surrounding metal has to get hot enough to temper some.

    I don't believe there is a free lunch. TANSTAAFL D[/QUOTE]

    I doubt very seriously if anyone has ever reached 11,000 F with TIG or any other welding process other than possibly plasma welding , since tungsten melts at 2800F and vaporizes at 10,000 F.

    A skilled TIG welder can "feather " the heat so it doesn't melt anything, many times we would clean dirty/corroded aluminum using AC hi-freq and low heat without melting the aluminum.

    By using the right combo of copper chill bars, heat paste, and gas backing the inside of the barrel he should have no trouble welding in a pin with a very small heat affected zone.

    JAY
    THE DEFINITION OF GUN CONTROL IS HITTING THE TARGET WITH YOUR FIRST SHOT
  • tennmiketennmike Senior Member Posts: 25,957 Senior Member
    BigDanS wrote: »
    Isn't it just the top of the pin welded / soldered, so the pin cannot be removed from the brake? My understanding is a tiny pinpoint torch could heat it and get the solder over it. I suppose you could drill the hole size in the brake slightly big and use some flux to get the silver solder into the space and make a joint with more connection.

    Regarding heat and oxidation, TIG is over 11,000 F for a short period. That's hot! I understand it is only at the point of the weld but the surrounding metal has to get hot enough to temper some.

    I don't believe there is a free lunch. TANSTAAFL


    D

    It's not a circumferential TIG weld; it's three spot welds. The time and heating for three spot TIG welds is insignificant, especially when compared to getting the parts hot enough to silver solder the pin in place. The cap weld over the pin should take no more than 20 seconds to fill in and make a domed puddle on top, and the two spot welds shouldn't take more than 15 seconds each to complete. The heating to do the same with silver solder will take several minutes and heat the barrel half way to the chamber. And silver solder doesn't take touch up blue worth spit, either.

    And if you've MIG welded, you know that getting the wire started EXACTLY on the spot you want, and a small spot at that, is danged near impossible. Close only counts with hand grenades and horse shoes. Cleaning up the welded area is a mess, and spatter is a sunny beach to clean up, and so is that welded metal where it wasn't supposed to be.

    I can and have done spot welds like that with 1/16" Arc welder, but that's with a welding helmet with auto darkening face shield so I can get the rod EXACTLY positioned before striking the arc.
    Do not meddle in the affairs of dragons, for you are crunchy and taste good with ketchup.


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