Announcement

Collapse
No announcement yet.

Welding Cast Aluminum (Help or Advice)

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Welding Cast Aluminum (Help or Advice)

    Hey Guys,

    I'm about to wander into uncharted waters. I want to attempt TIG-welding (or TIG brazing) cast aluminum. A piece (an "ear") has broken away from the main casting. The "ear" is small (perhaps 3/8" X 3/8" and is about 1/8" thick).

    I have been practicing on 1/8" thick aluminum bar stock and managing the welds quite nicely BUT bar stock is not cast aluminum. So, what can you tell me about welding billeted aluminum in comparison to cast aluminum?

    I am thinking that using a silicon-aluminum brazing filler material might be superior to attempting an actual weld. The only function of the ear is to provide an opposing hole for a roll pin in the AR15"s Lower Receiver trigger guard.

    My desire is to repair ...... not buy a new receiver so please stay focused on reparation rather than acquisition.

    Your thoughts and information on welding/brazing cast aluminum would be appreciated.


    Merry Christmas To All,
    Harold
    For those having fought for it, Freedom has a flavor the protected will never know.
    Freedom is only one generation away from extinction.

  • #2
    There is a small chance that someone will post some advice, and you'll
    fully grasp that advice, and execute a flawless repair on your part.

    The greater chance is that no matter the guidance you'll struggle
    for quite some time before you make any suitable welds on cast aluminum
    no matter what you try, or what advice you take. There are so many factors
    that make it not only difficult to do at all, but even from one weld scenario
    to another what you've gained may not fully apply.

    I'd do quite a bit of trial welding using what ever advice you find
    to many different examples until you succeed more often than fail.
    It's just the way it goes, unless you were one of the few
    that were just "born to weld" a natural is another way to say it.

    I am not among those few. I've had quite the struggle at first.
    And more than a few mentors said it was the rule, not exception
    just keep at it.
    Last edited by Old Hat; 12-26-2014, 04:07 AM.

    Comment


    • #3
      Originally posted by Old Hat View Post
      There is a small chance that someone will post some advice, and you'll
      fully grasp that advice, and execute a flawless repair on your part.

      The greater chance is that no matter the guidance you'll struggle
      for quite some time before you make any suitable welds on cast aluminum
      no matter what you try, or what advice you take. There are so many factors
      that make it not only difficult to do at all, but even from one weld scenario
      to another what you've gained may not fully apply.

      I'd do quite a bit of trial welding using what ever advice you find
      to many different examples until you succeed more often than fail.
      It's just the way it goes, unless you were one of the few
      that were just "born to weld" a natural is another way to say it.

      I am not among those few. I've had quite the struggle at first.
      And more than a few mentors said it was the rule, not exception
      just keep at it.
      Hi Phil,

      Very much appreciate your honest reply. I had a feeling that cast aluminum might be a problem. Perhaps tomorrow I will go to the junk yard and see if I can find some small cast aluminum parts to use as a means of exploration in order to see what it feels like to attempt cast welding. I have been considering such for several days but then I thought I might should first seek advice from those having gone before me.

      I appreciate your reply.

      Harold
      For those having fought for it, Freedom has a flavor the protected will never know.
      Freedom is only one generation away from extinction.

      Comment


      • #4
        Harold:
        A few basics might help a little. First as a concept, welding period
        is almost an opposite discipline than machining. Not only are you
        adding metal instead of removing metal, but you are seldom adding
        the exact same alloy in welding, where in machining, obviously it's all
        the same make-up you are dealing with... Unless yer machining welds!

        But the most significant difference is "who's Boss" so to speak.
        In machining YOU are in command. You can paint by numbers and it'll
        probably work. You can push the edge of the envelope, even brake the rules
        to some extent, and as long as you provide the balancing factors
        to the elements you've toyed with, it may still work. It may even work better.

        In welding YOU are never the Boss. The metal is the Boss.
        If anything good is going to happen, it's because you've discovered
        what the metal demands from you. And the metal, at least some metals
        like aluminum behave like Women. On a good day, if you have provided
        for all the variables, it will hint at what it wants from you. On a bad day
        it will lie all together and throw you completely off the sent.

        And they're all different, even when from the same family.
        A little thicker, the rules change. A little dirty, look out, it's gonna be ruff!
        Some have tricks just below the surface. Die cast can have bubbles in it.
        These bubbles may be uniformly distributed, or densely populated in one region
        and absent all together a half inch down the road. Aluminum likes Preheat,
        Sound familiar. But not too much mind you. Too much and it's over before you start.

        Stay in one place just a tad too long and you can have the whole bottom drop out.
        Or an entire corner suddenly melt away. Aluminum lies about when it's ready for filler.
        Once it looks molten, it's way too late in the game. A few moments earlier
        she was ready for You; but you would have never known it from the appearances on the surface.

        And the metal requires you to "give it" at some certain rate, and it's not in any text book.
        A welder that can Ace all the aluminum you can throw at him, is lie-ing if he says he's in command.
        He has Aced the game, but it's still the metal's game. He's learned to 'read' the lay of the land
        before he even flips the hood down. He's become vastly familiar with all the tricks.

        He's damn good at it and makes it look easy. But it's because he's either the rare natural,
        or he's done all his homework long ago and seen it all before.
        In other words this may take you a while. Good luck!

        NOTE;
        It took me a long long while to get to where I'm not gonna botch it as a rule.
        Longer than I'd like to admit, and no way do I sell myself as accomplished
        in welding aluminum. Just usually able, at best.
        Last edited by Old Hat; 12-26-2014, 10:47 AM.

        Comment


        • #5
          The above post is written in more of an off the cuff manner to encourage
          right brain involvement when approaching welding.

          The Mr Spock, purist mindset, of applying knowns to unknowns
          isn't gonna go it! You have to be willing to wing it to a degree
          and let it come to you. And sometimes just walk away and do something else.
          Last edited by Old Hat; 12-26-2014, 11:27 AM.

          Comment


          • #6
            Harold,

            I know you want to weld this, but sometimes the approach you want to "learn on" may not be the best approach and will only cause you pain and frustration.

            My wife asked me to fix one of those molded alum decorations behind a door knob on a china cabinet. It broke while she was trying to bend it back straight, so not only did I need to straighten it, I had to rejoin it. The working area was ~1/16" x 3/8" and the short piece was about an inch long. After much thought about how to weld it and a few (miserably) failed attempts, I ended up having great success by using 2 part epoxy to butt it together then the next day a piece of thin sheet metal 2 part epoxied across the back as a support.

            An ear will be much more difficult than a knob decoration because it likely needs to look good from both sides, but it lends credence to the theory that you shouldn't over-think things unless you absolutely do NOT have any other alternative but to weld it.

            Phil,

            Originally posted by Old Hat View Post
            A few basics might help a little. First as a concept, welding period
            is almost an opposite discipline than machining. Not only are you
            adding metal instead of removing metal, but you are seldom adding
            the exact same alloy in welding, where in machining, obviously it's all
            the same make-up you are dealing with... Unless yer machining welds!

            But the most significant difference is "who's Boss" so to speak.
            In machining YOU are in command. You can paint by numbers and it'll
            probably work. You can push the edge of the envelope, even brake the rules
            to some extent, and as long as you provide the balancing factors
            to the elements you've toyed with, it may still work. It may even work better.

            In welding YOU are never the Boss. The metal is the Boss.
            If anything good is going to happen, it's because you've discovered
            what the metal demands from you. And the metal, at least some metals
            like aluminum behave like Women. On a good day, if you have provided
            for all the variables, it will hint at what it wants from you. On a bad day
            it will lie all together and throw you completely off the sent.

            And they're all different, even when from the same family.
            A little thicker, the rules change. A little dirty, look out, it's gonna be ruff!
            Some have tricks just below the surface. Die cast can have bubbles in it.
            These bubbles may be uniformly distributed, or densely populated in one region
            and absent all together a half inch down the road. Aluminum likes Preheat,
            Sound familiar. But not too much mind you. Too much and it's over before you start.

            Stay in one place just a tad too long and you can have the whole bottom drop out.
            Or an entire corner suddenly melt away. Aluminum lies about when it's ready for filler.
            Once it looks molten, it's way too late in the game. A few moments earlier
            she was ready for You; but you would have never known it from the appearances on the surface.

            And the metal requires you to "give it" at some certain rate, and it's not in any text book.
            A welder that can Ace all the aluminum you can throw at him, is lie-ing if he says he's in command.
            He has Aced the game, but it's still the metal's game. He's learned to 'read' the lay of the land
            before he even flips the hood down. He's become vastly familiar with all the tricks.
            That.

            Was.

            Beautiful.

            The phrase "I'm the boss in my house. And my wife gives me permission to say that." rings true for welding as well. You have to do the bidding of the subject before you can command it to obey you, and it's not a one-time validation: You have to KEEP being a slave in order to continue being master.

            Comment


            • #7
              Originally posted by Billy Hill View Post

              The phrase "I'm the boss in my house. And my wife gives me permission to say that." rings true for welding as well.
              You have to do the bidding of the subject before you can command it to obey you, and it's not a one-time validation:
              You have to KEEP being a slave in order to continue being master.

              Thank You Billy.
              I see you have been traveling the same road my friend!

              Comment


              • #8
                I can't help you much. The cast aluminum bracket I fixed this week was a total pain in the rear. My piece was a thin, curved, hollow bracket that holds the blade to a ceiling fan. I total pain!

                As you tackle the project, treat it like a T joint where you are joining a small bar to a large plate. Practice with a 1/8 thick tab just like the one you will be working on and a big hunk of aluminum to get a feel for the rate that it will heat up.

                If, at any time, it feels like it's going bad you need to stop and let everything cool down and start again.

                Look into what snapped off the original piece.

                If possible, match the metals. That includes the replacement lug, filler and receiver.

                Good luck with it. Pictures will be appreciated.

                Dan
                At the end of the project, there is a profound difference between spare parts and left over parts.

                Location: SF East Bay.

                Comment


                • #9
                  As a novice, if I wanted to weld THIS I would machine a chunk of copper to fit between the 'ears' to hold them the proper spacing apart, file a good chamfer in the two sides, clamp the broken ear into place on the copper sink and TIG weld it hoping that the copper would stop the tiny 'ear' from melting away.
                  Peter - novice home machinist, modern motorcycle enthusiast.

                  Denford Viceroy 280 Synchro (11 x 24)
                  Herbert 0V adapted to R8 by 'Sir John'.
                  Monarch 10EE 1942

                  Comment


                  • #10
                    Hi All,

                    Dan asked for some images so I've quickly captured four images from various positions. I apologize for the quality. Normally I don't shoot Digital, rather, Large Format (5" x 7") film negatives or trannies.

                    Harold







                    For those having fought for it, Freedom has a flavor the protected will never know.
                    Freedom is only one generation away from extinction.

                    Comment


                    • #11
                      I know you aren't going to want to hear this, but what you have there is 7075 T-6 aluminum. Any attempt at welding 7000 series aluminum is doomed to failure using conventional welding methods. Google it.

                      Comment


                      • #12
                        Originally posted by Highpower View Post
                        I know you aren't going to want to hear this, but what you have there is 7075 T-6 aluminum. Any attempt at welding 7000 series aluminum is doomed to failure using conventional welding methods. Google it.
                        I was afraid that might be the case. I didn't know from which aluminum the receiver was cast but my local buddy had already warned me that if it was 7000 series then it wouldn't weld. Glad you mentioned that!!

                        I was looking earlier at a site called MuggyWeld and they had aluminum solder that was haled as the "cat's whiskers". Here is the site:

                        http://muggyweld.com/super-alloy-5

                        Wonder if this would work?


                        Harold
                        For those having fought for it, Freedom has a flavor the protected will never know.
                        Freedom is only one generation away from extinction.

                        Comment


                        • #13
                          Originally posted by Highpower View Post
                          I know you aren't going to want to hear this, but what you have there is 7075 T-6 aluminum. Any attempt at welding 7000 series aluminum is doomed to failure using conventional welding methods. Google it.
                          We've been welding aluminum professionally for more than 30 years so our situation is a bit different but what Highpower says about welding 7075 is generally true. We "have" welded it but, considering the applications where the alloy is used, there are times when you simply should not weld it. I know you want to "repair" as opposed to "replace" but sometimes your best option is to "punt"...

                          As an aside, if we were going to repair an ear that small we would likely just build up a block of material on that corner and then re-shape and re-drill it to suit--easier, and stronger, than trying to weld something that small. Whether building up or welding on the ear you would also need to remove every trace of anodizing from any area that's going to see any welding heat...
                          Keith
                          __________________________
                          Just one project too many--that's what finally got him...

                          Comment


                          • #14
                            Try'n to follow allong here.
                            Understood about 7075 being not a candidate for welding........
                            BUT
                            I've never heard of it being cast either.
                            Is the frame machined net from solid?

                            Comment


                            • #15
                              Originally posted by Old Hat View Post
                              Try'n to follow allong here.
                              Understood about 7075 being not a candidate for welding........
                              BUT
                              I've never heard of it being cast either.
                              Is the frame machined net from solid?
                              Hi Phil,

                              To the best of my knowledge, most lower receivers are cast using 7075 then certain areas on the cast are milled and refined to mil specs. Occasionally one will run across lowers that have been cut from billeted material.

                              Harold
                              For those having fought for it, Freedom has a flavor the protected will never know.
                              Freedom is only one generation away from extinction.

                              Comment

                              Working...
                              X