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  • Thick Aluminum Welding

    So I kinda underestimated Aluminum since I've got a Big, Kickass WelderTM (Miller 330 A/BP), but I found out the hard way that I am still in for a struggle.

    I was trying to build up a 1" spigot that got turned undersize on 6061 T6. It took way more power than I have ever used before, somewhere around the 300-320 amp range to get it to puddle. I did finally get it going and almost finished when I popped my 50A circuit breaker.

    I have a lot more of this to do. So, some questions I have:
    1. I have a number 18 watercooled torch. Should be no worried there? Looks like 350 amps 100% duty cycle to me.
    2. I've been using 3/32 electrodes. Would 1/8" work better?
    3. I ground my tungsten (2% Lanthinated) off square and then put a small chamfer on it. Flat down on a 1" block of aluminum I could not form a ball even at 60% in high range (320ish amps? Hard to say.) Do I really need that much juice to ball Lanthinated? Pure Tungsten balls very easily. Should I even worry about balling it? It was working at least.
    4. I need a plug in the end of some tubes to put threads in for a fastener. 1.5"x1/8" tube, and the plug will probably be 3/4-1" thick and recessed a short ways in. Is that even a good idea to attempt? Should I try those fancy, low temp brazing rods?
    5. I was having issues with my filler melting off from the radiant heat and dripping on the floor, but if, I pulled it further back much, it was out of the gas stream, and would oxidze and struggle to re-join the puddle. Would bigger filler help? I have 3/32" currently. Would a different gas lens help? I have #8 right now.
    6. What sort of gas flow should I be looking at for this type of work?
    7. Any suggestions of what hi-freq setting to use? I was at about 4/10 on the dial.
    8. I have a lot of dissimilar-size work coming up. 1/4-->0.065, 1/2-->1/8, stuff like that. Any suggestions? Have I already dug myself into a hole with my design?
    A picture for reference. Try not to laugh too hard. I'm still learning. I intended to go back and melt it in better but didn't have enough juice.

    Click image for larger version

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    21" Royersford Excelsior CamelBack Drillpress Restoration
    1943 Sidney 16x54 Lathe Restoration

  • #2
    Might check out weld.com. They have a YouTube channel also. I seem to vaguely recall some extras in welding gas to get it to weld thicker aluminum better. Sorry. My attempts with my 212 don't look as good as your picture on the thick stuff (I did it with MIG) so I don't have a certain answer.
    *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

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    • #3
      Originally posted by Bob La Londe View Post
      Might check out weld.com. They have a YouTube channel also. I seem to vaguely recall some extras in welding gas to get it to weld thicker aluminum better. Sorry. My attempts with my 212 don't look as good as your picture on the thick stuff (I did it with MIG) so I don't have a certain answer.
      How did mig work for you Bob? We've got a Lincoln 215 with a spool gun. Never tried it, but it might work ok for what I'm trying to do.
      21" Royersford Excelsior CamelBack Drillpress Restoration
      1943 Sidney 16x54 Lathe Restoration

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      • #4
        Originally posted by The Metal Butcher View Post

        How did mig work for you Bob? We've got a Lincoln 215 with a spool gun. Never tried it, but it might work ok for what I'm trying to do.
        I have found MIG seems to work ok from about .08 to about .25 for me with .125 to .250 being pretty easy. Cleanup is insanely critical with DC MIG. Atleast in my experience. Oxide removal with stainless wire brush immediately prior to welding. (Not a half hour before either) I got mediocre to passable welds upto 3/8 with lots of preheat. When I tried welding a large round tube (1/2in wall) into 1/2 plate I got results looking much worse than your picture. It stuck... but it looked absolutely terrible. I used straight argon with DCEP MIG. The reason I tried to steer you towards weld.com is I recall them using a different gas for thick aluminum welding. Maybe 2% helium or something like that. I just don't remember.

        When I MIGed aluminum I cleaned, brushed, and then cleaned with acetone immediately before welding. I have a little Miller Spool gun.

        I tried clean up with an angle grinder, but it did exactly what the weld.com guys said. It smeared the aluminum instead of brushing off the oxide layer. I bought a Harbor Freight Bauer battery operated angle grinder to try, because it turns much slower than your typical corded angle grinder. I have not tried it yet, and I have it locked in a work bench drawer in the front office so my son doesn't grab it and contaminate the brush. LOL.

        From what I understand a lot of production aluminum work is done with an AC Pulse MIG and push/pull guns. The machines I have seen that can do that are kind of pricey.

        One positive about MIG (maybe not for AC) is you can push all the power you have without burning up your gun.
        *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

        Comment


        • #5
          Originally posted by Bob La Londe View Post

          I have found MIG seems to work ok from about .08 to about .25 for me with .125 to .250 being pretty easy. Cleanup is insanely critical with DC MIG. Atleast in my experience. Oxide removal with stainless wire brush immediately prior to welding. (Not a half hour before either) I got mediocre to passable welds upto 3/8 with lots of preheat. When I tried welding a large round tube (1/2in wall) into 1/2 plate I got results looking much worse than your picture. It stuck... but it looked absolutely terrible. I used straight argon with DCEP MIG. The reason I tried to steer you towards weld.com is I recall them using a different gas for thick aluminum welding. Maybe 2% helium or something like that. I just don't remember.

          When I MIGed aluminum I cleaned, brushed, and then cleaned with acetone immediately before welding. I have a little Miller Spool gun.

          I tried clean up with an angle grinder, but it did exactly what the weld.com guys said. It smeared the aluminum instead of brushing off the oxide layer. I bought a Harbor Freight Bauer battery operated angle grinder to try, because it turns much slower than your typical corded angle grinder. I have not tried it yet, and I have it locked in a work bench drawer in the front office so my son doesn't grab it and contaminate the brush. LOL.

          From what I understand a lot of production aluminum work is done with an AC Pulse MIG and push/pull guns. The machines I have seen that can do that are kind of pricey.

          One positive about MIG (maybe not for AC) is you can push all the power you have without burning up your gun.
          Good info, thanks. That may be useful on a lot of the tube work. Though I can tig 1/8" ok. Certainly the machine is plenty capable.

          Ah yes. Helium. That may indeed be worth a shot. I'll do some reading. IIRC you're right, it give you some extra heat from the gas.

          I'm pretty lazy about cleaning with TIG. I've been sort of letting the arc do it for me. I should do a bit more cleanup in the future. There is a push-pull mig on campus, but it was having issues last I saw and I don't get along super great with the instructor. I saw the last welds done with it. The material was pretty thick, and they stuck, but they weren't exactly pretty.
          21" Royersford Excelsior CamelBack Drillpress Restoration
          1943 Sidney 16x54 Lathe Restoration

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          • #6
            For such high amps a larger electrode will pass more of the power to the work.

            It looks like you were trying to do it in a single pass. That should be done in several passes with a smaller bead. I think.

            Preheat is definitely called for.

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

            Location: SF East Bay.

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            • #7
              One other thing I should mention. I tried way over building up the weld on the thick stuff and then machining it back. It looked terrible from the surface to as deep as I machined it.
              *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

              Comment


              • #8
                Originally posted by danlb View Post
                For such high amps a larger electrode will pass more of the power to the work.

                It looks like you were trying to do it in a single pass. That should be done in several passes with a smaller bead. I think.

                Preheat is definitely called for.

                Dan
                Well, once I actually got the puddle flowing, it was about 3/4" in diameter. With me shaking around. My filler dripping on the floor, my filler glove smoking 5" away, it's amazining I got anything in there at all. Preheating is a good idea and will be attempted in the future, especially when I have some spare manpower to run a torch.

                Originally posted by Bob La Londe View Post
                One other thing I should mention. I tried way over building up the weld on the thick stuff and then machining it back. It looked terrible from the surface to as deep as I machined it.
                Interesting. I already counted the part as scrap, more or less, and roughed in a new one. On my big lathe I can rough it faster than I can weld it anyway. But I figured I might as well try to save it and have a 2nd spare. Good practice as well.
                21" Royersford Excelsior CamelBack Drillpress Restoration
                1943 Sidney 16x54 Lathe Restoration

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                • #9
                  My suggestions based on very limited aluminum TIG,

                  Go with the 1/8” tungsten at those amps.

                  Definitely put some preheat into it.

                  It looks like you tried starting where the little journal sticking out meets the bigger flange. Start the weld at the end of the little journal and work your way in, there will be less of a “heat sink” at that end and as you work your way towards the flange heat will have been building up in it.

                  You should be able to do the tubes with the ends in it no problem. I feel confident I could do them on my TA186 and that is only a 200 amp machine.

                  And yes, iirc a 50amp breaker is undersized for that machine at full power. It probably needs more like a 75-80 amp breaker.

                  Comment


                  • #10
                    Originally posted by oxford View Post
                    My suggestions based on very limited aluminum TIG,

                    Go with the 1/8” tungsten at those amps.

                    Definitely put some preheat into it.

                    It looks like you tried starting where the little journal sticking out meets the bigger flange. Start the weld at the end of the little journal and work your way in, there will be less of a “heat sink” at that end and as you work your way towards the flange heat will have been building up in it.

                    You should be able to do the tubes with the ends in it no problem. I feel confident I could do them on my TA186 and that is only a 200 amp machine.

                    And yes, iirc a 50amp breaker is undersized for that machine at full power. It probably needs more like a 75-80 amp breaker.
                    Correct. I will start it at the end in the future. Thanks!

                    It need a 100 amp breaker for full power. 96 amps according to the manual. 50 is definitely undersized, but it was "good enough" til now. Dad doesn't want to spend a few hundred on wire and conduit to do it right, understandably so.
                    21" Royersford Excelsior CamelBack Drillpress Restoration
                    1943 Sidney 16x54 Lathe Restoration

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                    • #11
                      Power consumption on the inverter welders is a big plus over the transformer welders. I would have ended up with Syncrowave 200 (or bigger) if is wasn’t for the power requirements.

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                      • #12
                        Some success.

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                        Those are the tube ends. Ended up setting up a janky rotary jig with a 12" rotary table, 12.5" Bison 6 jaw plopped on there and an assistant to rotate. Started at 230 amps with a big 45 degree chamfer on the plug. I tried to heat only the plug as the edge of my cone would like to melt the tube if it wasn't sharp enough. The first pass sometimes touched up against the tube, but didn't penetrate. I was basically just adding material back in that I took out and heating it. On the second pass it wicked in to the tube good and I had to flow in a ton more filler, which made me confident I was actually getting some penetration.

                        The 1/2" plate... different story. I could just get it to puddle at 60%. So that would theoretically be 337 amps. When I did try to jam my rod into the the puddle it just blew it away like there was a fan on it or something. Arc blow? After hitting it as much as I dared with the Rosebud, I could get it to puddle and finally was able to lay a bead in on the 1/2" to 1/4" connection. It roasted my 3/32 tungsten, cracked end on one, off-center, globy, ballish thing on the other. So don't look too close, eh?

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                        I will say I learned more that day than any other day of tig welding. I'm starting to get a feel for when the puddle is flowing in well, the changes that tungsten grind makes, what the arc cone is looking like and it's sphere of influence, when my material is hot enough to actually penetrate, preheating, etc. Lots of success even given some failures.

                        But with that said, I've got a lot more to learn, and a lot more 1/2" plate to weld. I'll try to do it myself, but I may outsource it if I think I'll struggle too much. Preheating is definitely in order.

                        Originally posted by danlb View Post
                        For such high amps a larger electrode will pass more of the power to the work.

                        It looks like you were trying to do it in a single pass. That should be done in several passes with a smaller bead. I think.

                        Preheat is definitely called for.
                        Agreed. I'm going to look into 1/8" tungsten Monday, I think that's the biggest I can push on my 18 torch.

                        Agreed.

                        Agreed.

                        Originally posted by oxford View Post
                        Go with the 1/8” tungsten at those amps.

                        Definitely put some preheat into it.

                        You should be able to do the tubes with the ends in it no problem. I feel confident I could do them on my TA186 and that is only a 200 amp machine.

                        And yes, iirc a 50amp breaker is undersized for that machine at full power. It probably needs more like a 75-80 amp breaker.
                        Yup, yup, and yes, I think your 200 amp machine could have done it with some preheat. As said, I was up at 230 amps, but an experience welder using some tricks to their advantage could almost certainly get it done. I was well below 200 amps by the end of the pass. Especially if you can bias the AC time do direct more heat into the metal.

                        60 amp breaker made a difference. Wire never got hot at all.

                        Originally posted by Bob La Londe View Post
                        One other thing I should mention. I tried way over building up the weld on the thick stuff and then machining it back. It looked terrible from the surface to as deep as I machined it.
                        Dead right Bob. I had never even tried machining welded aluminum. Turns like pure garbage so I was wasting my time on the hub anyway. I'm going to see if I can use the furnaces at work to heat treat these back to T6ish.

                        A few more questions. Paging @nickle-city-fab for his welding knowledge.
                        1. Anyone ever tried half-wave rectification? I don't really have access to that machine, but I'd switch it if it really made a difference for Aluminum. Two figures below giving Miller's thoughts.
                        2. Max preheat temperature that I should adhere to? 700F maybe? I'm gonna buy another crayon, those are dope.
                        3. Advice for tungsten grinds for pushing max power? I don't know that I can get a nice, pretty ball without blowing a breaker. Probably not at all on 1/8, idk if 435 amps would even do it.
                        4. Cup size recommendation?
                        5. Flow rate recommendation?
                        6. Should I get some Helium? :P Getting the bottles refilled Tues.
                        7. Any other advice? If I still have trouble I guess I'll resort to a proper welding forum like suggested. Ugh, more passwords to keep track of.
                        Last edited by The Metal Butcher; 03-08-2021, 01:07 AM.
                        21" Royersford Excelsior CamelBack Drillpress Restoration
                        1943 Sidney 16x54 Lathe Restoration

                        Comment


                        • #13
                          TMB: I'm sorry I didn't get back to you sooner -- I took a short vacation from the internet.

                          YES, definitely a larger electrode, at least 1/8 or the biggest you can get for your torch.

                          Gas lens is good to have

                          liquid cooling is perfect this is the exact kind of job it was made for

                          sometimes a narrower cup dia helps keep the gas flowing further out from the tip. The cup is used most often was about 1/2" dia and 1" long on a #17 torch.

                          Far as balling your tungsten, I have had similar problems with the lanthanated stuff, so I switch back to the old-school standby using 1/8" thoriated (the red stripe ones). You cannot ball tungsten on alu. You need to keep a small block of scrap steel around and ball your tungsten over that. It will ball up within seconds.

                          YES bigger filler -- the smallest I used on alu jobs was 3/32 but 1/8 was way better.

                          Hi freq settings: I prefer a "balanced" arc or one that favors the "cleaning" action. Try starting around 5 or 6 on your dial on some smaller pieces of scrap. Experiment with the entire range of the dial.

                          RELATED to arc balance and cleaning -- I had the best luck regardless of machine settings, by scrubbing the area with soap-water and stainless toothbrush immediately prior to starting the arc. Start the arc right up on the soap-water, don't let the part get too dry. The alkaline nature of soap disrupts the aluminum oxide layer and makes the welding machines job much easier. You'll see the crap float out to the top and edges of the puddle.

                          EDIT on larger jobs like yours it was a thing to take well-timed breaks and let the heat dissipate before doing a bit more weld. Trying to do it continuous is simply not possible on some job when the thermal mass vs the thermal conductivity starts to bite you

                          I tried to avoid dissimilar sections of metal like the plague because they are such a PITA but if it was my job to do it, then I had to suck it up and do it. Aim your heat into the heavy part, favor it by a say 30 or 40%

                          Your greatest challenge in this job is the thermal properties of alu. I wicks the heat away so fast that by the time you have enough heat built up to fusion, the entire part is cooking and falling apart and etc. You can try insulating the parts that are not in the immediate area of the weld with some hi-temp wool. You can try preheating with an oxyacetylene torch on the weld area, scrub with the soap-water, and then weld -- you have to move with instant cat reflexes to do this but it can get you out in a jam.

                          The easiest way is when you can put enough amps into the metal to get fusion *before* the heat has a chance to travel throughout the piece. Alu is the second worst for this -- copper is the worst. You are fighting the inherent thermal conductivity, and even more so with different section thicknesses.

                          I would practice up on some 1/4" scrap pieces or similar, get comfy to where you can kick the machine wide open on a cold start and get a puddle in seconds. Like I said, on the heavy stuff (anything over 1/2") you might have an easier time preheating in a very narrow area first.

                          Alu and steel don't mix. You can get some big blocks of steel and clamp them onto the alu to act as heat sinks and then wide open on the machine to start. This makes dealing with thin parts easier.

                          Your overall setup is good and logical, but maybe marginal for the thickness (I always used to calculate the watts per sq area and you want a *lot* on alu, you want as much possible) -- I think it can be done, it's just a matter of getting your procedure dialed in.

                          Good luck, lemme know how it goes.
                          Last edited by nickel-city-fab; 03-09-2021, 04:40 PM.

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                          • #14
                            TMB: I forgot to add, that straight helium gives a hotter arc, but its definitely more expensive. My employers all used straight argon. Argon has a nice quiet and smooth puddle, helium had godzilla penetration but not as stable as argon. Required closer attention to arc length and travel, etc.

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                            • #15
                              TMB: even more analysis/advice:

                              what is limiting you right now is what I call the "available energy density" at the electrode. To form a puddle you have to be able to pump x number of watts in the material in y amount of time. Alu is very conductive, so the wattage requirement goes way up. if I could get a 5/32 or even a 3/16 electrode in there I would. Since the energy density is going to be constrained by the electrode diameter, and the max output of the machine. You have to be able to "slam" the part with a huge jolt of watts in getting the puddle started. But the thickness of the part is going to determine how huge that jolt is. The thickness of the electrode is gonna determain how much jolt you can give.

                              Using too small an electrode simply heats up the whole part, and doesn't give the desired result as you've found out. 3/32 or 1/8 is good for thinner metals such as anything up to around 1/4"

                              You can "overdrive" your electrode as you found out, but it usually doesn't help. I try to limit my amps to no more than 150% of electrode dia. so 1/8" is normally 125 amps, and I limit the max to 180 amps or there abouts with 1/8". Else the tools and the job just falls apart.
                              Last edited by nickel-city-fab; 03-09-2021, 04:42 PM.

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