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MIG on Alu thoughts.

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  • MIG on Alu thoughts.

    For some darn reason I just haven't gotten around to trying this. Have had the MIG with reversible polarity for years, but have always relied on TIG anyways. So what the heck, right? Might as well spark it up. Anything to keep in mind? Clean joint, stainless steel brush? As per the usual? Pure Argon okay?

  • #2
    Unless you have a spool gun, it is really hard to feed aluminum wire.

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    • #3
      Yes pure Argon is ok, it's recomended... least oon my machine - Miller 210

      Walt
      Walt

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      • #4
        A teflon liner and different rollers. Like suggested a spool gun works real nice. JRouche
        My old yahoo group. Bridgeport Mill Group

        https://groups.yahoo.com/neo/groups/...port_mill/info

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        • #5
          I've pushed pounds of .30 Alum wire. 100% Argon and plastic line are a must. You'll have to play the feed roller presure to get it right... once set you'll be fine.

          Tim
          Wow... where did the time go. I could of swore I was only out there for an hour.

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          • #6
            Teflon liner - best used with a Miller Push/Pull Aluminum MIG machine - they really work well. I prefer TIG on Aluminum - always looks good - unlike the rat **** you can get with the Aluminum MIG especially with just the spool gun or regular feed - not pretty at all.

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            • #7
              I used to work in a boat shop- they made aluminum hulls from 12' skiffs upt to 40+ foot stern-picker fishing boats.

              They had two or three "Cobramatic" wirefeed MIGs, the ones with the fat gun with it's own wirefeed drive. These guys could lay down some fairly impressive beads with these guns, and quite quickly too.

              They also had at least one standard TIG and a heavily-modified wirefeed TIG-gun. These were used for the projects that needed better weld control.

              Now, in the years since, I have seen very few people run an aluminum MIG nearly as well. Most, in fact, suck- it's probably not the weldor, I believe it's the fact they're trying to use aluminum wire in a push-only stinger (that and in a lot of cases trying to use a 110V machine.)

              As the others said- teflon liner is a must. Needs to be a heavier machine, a 110V won't cut it except on the lightest materials. Pure Argon; although Helium is supposed to give a hotter arc with the TIG, I don't know if that holds true with the MIG as well. Keep the stinger cable as straight as possible, and keep bends to the largest conveninent radius. You'll need serrated or roughened rollers to get a grip on thew wire. Reduce spool tension to near-zero. (Just enough to prevent a snarl.)

              And cleanliness is even more important than with a TIG. Scotchbrite, stainless wire brush, chemical etch and/or acetone- and like the book says, don't clean today and weld tomorrow; clean today and weld right now!.

              Doc.
              Doc's Machine. (Probably not what you expect.)

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              • #8
                I used the teflon liner up until about a month ago. Mine is a push and uses a rubber drive wheel and a teflon liner when I switch to alum. It has always been a bit of a pain but usually only when I was putting too many bends in the cable. I got pretty good results if I kept my hose as streight as possible. Last month I forgot to change to the teflon liner. What a difference. I now have the smoothest feed I have ever had using the liner for steel wire. I don't no how long this will last but what a difference. Bends in the line seem to have no affect either. I will never go back to teflon again if I don't have to.

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                • #9
                  Largest tip possible,like an .045 or .059,put a slight bend in it to make contact.Use the teflon liner on hopefully a short whip(8 foot is okay,6 is better) and use small wire .023.

                  It helps dramaticly to preheat,sometimes just setting the part out in the sun does the trick,heat gun also helps.Don't use a propane torch,water vapor will deposit on the surface and make it a beach to weld.

                  Keep the nozzle moving,your moving too slow when you hear it pop and sizzle.It should sound like an air leak when welding.
                  I just need one more tool,just one!

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                  • #10
                    I got a spool gun and controller for my miller 175 but I have only used it once so I cant give a fair assement as it was my first attempt a welding Alu and I think I was most of my problem


                    Matt in AK
                    Matt in AK

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                    • #11
                      BTW.........why do you need reversible polarity?

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                      • #12
                        <font face="Verdana, Arial" size="2">Originally posted by gunsmith:
                        Last month I forgot to change to the teflon liner. What a difference. I now have the smoothest feed I have ever had using the liner for steel wire.</font>
                        -The probelm is that it works great for a while. Then the liner (spiral wire conduit) starts to fill up with fine aluminum dust scrubbed off the wire as it flows past. Eventually it'll clog and jam, in some case badly enough that the wire is unremovable.

                        Also, if you switch back to steel after extensive aluminum wire use, the aluminum dust contaminates the tip and weld.

                        Doc.
                        Doc's Machine. (Probably not what you expect.)

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                        • #13
                          Ah, gracias for all input. Like usual with these things, I probably won't get around to doing it for at least an hour, maybe two weeks.

                          Right, the teflon liner... Think I have some. (Y'all remember when you could buy it at the bike store? Probably a huge price hike, but convenient. Speaking of which, I'm sure most of you have noticed that wirefeed welder cable = Bowden cable = bike brake cable housing. Used it once to make a fifteen foot long one once; worked great. However, I digress...)

                          Right, then: Thrud, about the bird**** welds- Well yes, but the same applies to welding steel too, until you learn to do it properly. Like anything else.

                          Doc Nick, Weird et al, thanks for the practical tips; I'll keep them in mind.

                          And Paul, about reversible polarity: Not sure if you're asking or hinting. Reversed polarity is used on Alu to provide a sort of an electrical ion blasting blasting effect to remove the alu oxides, which have a much higher melting temperature than the metal itself. Something like that.

                          If you meant to imply that it isn't needed on MIG, maybe you're right... That's the way it is on TIG, so I just presumed so for MIG too. Now that you've raised that shadow of doubt, I'm not quite so sure anymore. Well, it won't take long to notice anyway.

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                          • #14
                            <font face="Verdana, Arial" size="2">Originally posted by Dr. Rob:
                            about reversible polarity: Reversed polarity is used on Alu to provide a sort of an electrical ion blasting blasting effect to remove the alu oxides, which have a much higher melting temperature than the metal itself. Something like that.</font>
                            Actually not just reverse polarity but an AC (alternating current) power source. The AC breaks up the thin layer of aluminum oxide.

                            It is the pulling (positive to negative) affect the positive portion of the wave form has on the weld puddle that scatters the oxide layer. That allows the next wave form (negative to positive) to melt the base material.

                            The high frequency circuit of a TIG welder accomplishes this continuously due to the amount (ratio) of positive cycles compared to the power circuits cycles (60hz). This is why we use continuous high freq. while welding on aluminum. JRouche
                            My old yahoo group. Bridgeport Mill Group

                            https://groups.yahoo.com/neo/groups/...port_mill/info

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