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  • DC Tig Aluminum

    I remember seeing a thread about DC Tig on thicker pieces of aluminum, but can't find it with search. Does anybody remember this? I can't remember when it was appropriate/desirable to use DC Tig instead of AC, but I seem to remember somebody saying they preferred DC to AC on thicker stuff.

    I'm looking into buying some equipment and trying to decide what capabilities I will need vs. want vs. check book balance. I'm looking at getting something like a shopmate and a feeder for MIG, but if I spent a few bucks more (for the shopmate anyway), I can get the DX that can do lift arc DC Tig as well. Once I'm at or above 1/4" aluminum, would it be worth having the DC Tig capability, or would I be better off trying to MIG it? I haven't tried MIG on aluminum yet, so I don't know how well it works. The little MIG unit I have now will not feed .035 aluminum wire no matter what I've tried, but I would expect something like an S-22/24 feeder to be a little more forgiving, especially on thicker wire.

    PS. I set the cutoff point at 1/4" because I'm planning on getting a Dynasty 200DX, which should be able to handle everything up to 1/4" with no problem.

  • #2
    Check the Miller "Ask Andy" site, I think Hawk had some threads on welding DC tig aluminum using UTP He for gas. You can find them if you do a search in the archives for his handle. Personally I use my Dynasty 200DX for up to 3/16" then switch to a spoolgun for anything thicker, works for me.
    Regards, George

    Hobart Handler 210 w/DP3035 - Great 240V small Mig
    Hobart Handler 140 - Great 120V Mig
    Hobart Handler EZ125 - IMO the best 120V Flux Core only machine

    Miller Dynasty 200DX with cooler of my design, works for me
    Miller Spectrum 375 - Nice Cutter

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    • #3
      Originally posted by kyoders View Post
      I remember seeing a thread about DC Tig on thicker pieces of aluminum, but can't find it with search. Does anybody remember this? I can't remember when it was appropriate/desirable to use DC Tig instead of AC, but I seem to remember somebody saying they preferred DC to AC on thicker stuff.
      I have tried DC TIG on aluminum and all I can say is if you think AC TIG of aluminum can be a challenge to get a nice weld, DC TIG is next to impossible. It will weld but you will not be happy with the result. I'm told that using helium instead of argon as a shielding gas would make it a little easier but I have not tried that.

      I have MIG welded aluminum as well and as long as you can get your machine to feed it reliably, it's not much harder or different than welding steel. The one thing I noticed was wire speed needs to be fast to keep the amps up and so travel speed had to be FAST. Might just be my machine but anyway, it does MIG nicely, no big deal.

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      • #4
        It sounds like I should not bother taking DC Tig capabilities into account when looking for the CV power source. I'd probably be better off putting more money into a feeder that can reliably feed aluminum wire. Thanks for the feedback.

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        • #5
          Originally posted by kyoders View Post
          It sounds like I should not bother taking DC Tig capabilities into account when looking for the CV power source. I'd probably be better off putting more money into a feeder that can reliably feed aluminum wire. Thanks for the feedback.

          Not the case ,,,,,,,,,,,Let me hunt a minute

          One of the pro's here does it !!
          sigpicViceGrip
          Negative people have a problem for every solution

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          • #6
            post # 3 in this thread

            http://www.hobartwelders.com/mboard/...icker+aluminum

            engloid .....how-ever another guy went into details

            said it's everday buisness where he works
            sigpicViceGrip
            Negative people have a problem for every solution

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            • #7
              That sounds like the one I'm remembering. If you have better luck finding it, I would love to see it again. I'm always looking for an excuse to buy bigger/better machines.

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              • #8
                I'm outta Time for now

                a little activity and sone-one will remember

                the contributor had a long name

                aametalmaster / presisionworks ....or the like I think

                emphasis was DC helium ?
                & clean-prep

                Phil
                sigpicViceGrip
                Negative people have a problem for every solution

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                • #9
                  I've never tried it but I looked into DC tig when I first built my scratch start rig. What I read is that the majority of the heat will be directed into the tungsten and as a result you need a torch that can deal with a lot of heat and thick tungsten. Since I have neither I never bothered to hook it up.

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                  • #10
                    I DC aluminum almost everyday. It is the standard repair process for the rockets that we build. You will need lab grade helium to get nice shiney welds though. It is most definitley worth it if you are going to be welding lots of aluminum over .125 thick.
                    Two turn tables and a microphone.

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                    • #11
                      Originally posted by Pangea View Post
                      I DC aluminum almost everyday. It is the standard repair process for the rockets that we build. You will need lab grade helium to get nice shiney welds though. It is most definitley worth it if you are going to be welding lots of aluminum over .125 thick.
                      You must be pretty good at it.

                      Like I said, I tried it and it was tricky and I didn't like the appearance (but I didn't have helium). I can AC TIG weld aluminum without much trouble but trying DC was definitely a challenge and, looking at the welds I produced, I'd have to say I could not do it.

                      Other than the lab grade helium, and I assume lab grade cleaning of the work and the wire, are there other "tricks of the trade" or is it like everything else, practice, practice, practice? . . .

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                      • #12
                        Thanks Pangea. Knowing that it is pssible and even recommended for larger stuff, I may go ahead and spend the extra money now and get a CC/CV. In the case of the Miller shopmate, it's some where in the vicinity of $400 more to get the DX (CC/CV) vs standard (CV only). That's a lot cheaper than wanting to buy another welder later on (not that that would discourage me ).

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                        • #13
                          Cleaning the parent material is one of the key elements to ensure a weld that will pass the strict requirements we are held to. We wire brush with a soft stainless wheel or stiff stainless steel tooth brush to remove alodine coatings if they are present. Acid etch, wire brush again, then srape the faying surfaces.

                          On repairs we use a cutter wheel and a highspeed air grinder. The grinder has had acetone run through it, then alcohol to remove all oils. Air grinders don't last long that way. After cutting to remove discontinuities(porosity or tungsten inclusions from VPPAW) we wire brush the immediate area and weld asap.

                          The 2% thoriated tungsten is ground to a 30ish degree angle with a flat tip. The flat tip will keep you from getting tungsten inclusions from shedding. The flattened area of the tip is about .005 to .015.

                          The rest of the WPS is proprietary information. Try amperages and shilding gas flows close to what you would do with steel.

                          Terminate the weld by back tracking and tailout on your rod. Grind starts and stops to eleminate cold laps and startup porosity.

                          If there is anything else you need to know, feel free to ask.

                          Good luck.
                          Two turn tables and a microphone.

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                          • #14
                            The biggest problems I had with DC TIG on Al were that the aluminum would not flow -- it was definitely clean but still behaved as if oxidized. A real challenge to weld. The only thing I can think of is to add WAY more heat -- but then the parts would melt and drop into my lap.

                            Is that common or how do you actually do this?

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                            • #15
                              Originally posted by kyoders View Post
                              Thanks Pangea. Knowing that it is pssible and even recommended for larger stuff, I may go ahead and spend the extra money now and get a CC/CV. In the case of the Miller shopmate, it's some where in the vicinity of $400 more to get the DX (CC/CV) vs standard (CV only). That's a lot cheaper than wanting to buy another welder later on (not that that would discourage me ).
                              Try it first.

                              The guy who welds rockets has to be really, really good at it (like decades of practice). I'm serious, try it and you will see what I'm talking about. It's really hard to do. If you think TIG in general is a high skill weld, try that.

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