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  • Another new guy here, and a couple of questions

    Hi all. I've been reading this forum for a while, and finally figured out how to sign up.

    I have inherited an Airco Heliwelder 300, circa 1963. I believe it crosses with a Miller 330 A/BP. As others have posted here, 900 lbs of awesome!

    The unit has been in storage for a while I built a new facility to house it (previous owner died). It's now back together and running again, so I get to get back into practice

    Two questions:

    1. Can somebody advise me on straight polarity vs reverse? The PO could never give me a coherent answer on when you use one vs the other. Reading about it, the best explanation I've seen is that straight will produce better penetration, and reverse will work better to remove leftover crud on the surface. Does that make sense?

    2. Can anybody identify the torch in the pix below? I think it's a weldcraft, but the label is so beat up I can't really tell. I'd like to get some fresh ceramic cones for it, and I want to know what to buy.

    Thanks in advance for any info.


  • #2
    Welcome! Glad you joined up. You have a real beast there, that will still be welding after all of us are dead and gone! A true and fine classic, as long as you don't have to move it much!

    On the issue of polarity, it depends on what kind of welding you're doing. For TIG welding, you will use straight polarity (electrode negative, or EN) for all but aluminum, which requires AC rather than DC. If you try tig on reverse polarity (EP), you will toast your tungsten electrode in very short order. TIG requires CLEAN CLEAN CLEAN material. On steel, grind off any mill scale first. Clean with acetone before welding. The clean concern is doubly so on aluminum--. Safety note: DO NOT use brake cleaner in place of acetone--alcohol works but acetone is the standard. Brake cleaner + heat + argon = nerve gas--you probably only get to make the mistake once.

    For aluminum, AC is necessary to blast away the aluminum oxide so you can get down to the bare metal--it's called cleaning action, and you will see an area around the weld that is different color due to the cleaning action. Here's a link on AC for aluminum.
    https://www.millerwelds.com/resources/article-library/understanding-ac-tig-balance-control


    For stick welding, reverse polarity gives much better penetration than straight, and is good at being able to blow away rust and paint, although it's best to clean up the material first. Most stick welding you do will be reverse. The most commonly considered advantage of straight polarity is very high fill rates, but you can get great fill rates with 7018 rod on reverse polarity. Plus, the 7018 is a low hydrogen electrode; when steel is heated up (as in welding) and absorbs hydrogen from the air, it becomes brittle and cracks. The only downside with 7018 is it absorbs moisture from the air and loses its low hydrogen properties; have to keep it fresh and dry; often kept in an oven. It will still weld, just won't have the spec properties if it gets old and absorbs moisture. You can study stick electrodes here:

    https://www.hobartbrothers.com/products/stick-electrodes.html

    Can't help you on the torch; I'm pretty old, but in the old days I was only stick welding. There are plenty of guys here with far more experience than I, and I'm sure more info will be coming soon.

    Last edited by Aeronca41; 04-01-2020, 10:24 AM.

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    • #3
      Just another note--I posted the link on AC balance for aluminum, but I think your welder was in an era before balance controls, so I think you just have 50/50 balance,

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      • #4
        Thanks Aeronca. Yes, I know about AC for Al. I've done enough of that to appreciate how tricky it is I also get the clean-material thing. I should say that I've been using this welder for years, as it used to be in my friend's shop. He died a couple of years ago, and I'm just getting my own shop into shape and moving in the tools, including this unit. So I have some experience with it, though I'm far from an expert.

        On the polarity, ok, got it. Reverse only works for stick. That makes a lot of sense.

        Re AC balance, I'm sure you're right, 50/50 is all this machine can do. It's beefy and low-tech by today's standards, nothing fancy like settable AC balance.

        It's an impressive machine. They weren't fooling around when they built this one.

        BTW one of my current projects is a 1941 T-craft

        Thanks again.

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        • #5
          Looks a little like a water cooled Airco A20 series.
          A way to check is to see if the tungsten collet is one piece versus two.

          https://www.ckworldwide.com/airco.html
          Miller Dynasty 350, Dynasty 210 DX, Hypertherm 1000, Thermal Arc GTSW400, Airco Heliwelder II, oxy-fuel setup, metal cutting bandsaw, air compressor, drill press, large first aid kit, etc.

          Call me the "Clouseau" of welding !

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          • #6
            Originally posted by jrd-airco300 View Post
            Thanks Aeronca. Yes, I know about AC for Al. I've done enough of that to appreciate how tricky it is I also get the clean-material thing. I should say that I've been using this welder for years, as it used to be in my friend's shop. He died a couple of years ago, and I'm just getting my own shop into shape and moving in the tools, including this unit. So I have some experience with it, though I'm far from an expert.

            On the polarity, ok, got it. Reverse only works for stick. That makes a lot of sense.

            Re AC balance, I'm sure you're right, 50/50 is all this machine can do. It's beefy and low-tech by today's standards, nothing fancy like settable AC balance.

            It's an impressive machine. They weren't fooling around when they built this one.

            BTW one of my current projects is a 1941 T-craft

            Thanks again.
            Wish I could say the Aeronca is a current project--I like the sound of that.

            BC-12D? Got a lot of hours in one of those as a kid with dad. The L-3 is in parts in the upstairs of my garage--dad was in the middle of refurb when he died. Now "recovering" from caregiving and then loss of my wife and my mom in the last two years, dealing with estates, taxes, loads of fun. But the end is in sight! Just got a call from the CPA while typing this, and the second-to-last tax hurdle is done!

            Didn't understand what you may or may not know about welding, so maybe I got a little pedantic, but I think you understand.

            Enjoy that old monster, and search out some of the posts here by Ryan Jones (I'm sure he will post to this one soon--he's pretty active here). His is named Helga the Heliwelder.

            Comment


            • #7
              Originally posted by Burnt hands View Post
              Looks a little like a water cooled Airco A20 series.
              A way to check is to see if the tungsten collet is one piece versus two.

              https://www.ckworldwide.com/airco.html
              Ah, ok, that looks close. Looks kind of like the CKA35. That would make sense, as this is a 300A welder.

              The collet is one piece.

              Does that help ID which ceramics I should get?

              Thanks!

              Comment


              • #8
                Originally posted by Aeronca41 View Post

                Wish I could say the Aeronca is a current project--I like the sound of that.

                BC-12D? Got a lot of hours in one of those as a kid with dad. The L-3 is in parts in the upstairs of my garage--dad was in the middle of refurb when he died. Now "recovering" from caregiving and then loss of my wife and my mom in the last two years, dealing with estates, taxes, loads of fun. But the end is in sight! Just got a call from the CPA while typing this, and the second-to-last tax hurdle is done!

                Didn't understand what you may or may not know about welding, so maybe I got a little pedantic, but I think you understand.

                Enjoy that old monster, and search out some of the posts here by Ryan Jones (I'm sure he will post to this one soon--he's pretty active here). His is named Helga the Heliwelder.
                The project plane is a 1941 BL12. Kind of unique. It was built for export, but WWII got in the way. It got as far as Canada, but was called back. I have the original metric instruments

                No sweat on welding advice. I've done some, enough to know I need to learn a lot more. I'm always happy to get input. Thanks!

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                • #9
                  I'll have to look up the BL 12. A new one for me.

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                  • #10
                    Originally posted by Aeronca41 View Post
                    I'll have to look up the BL 12. A new one for me.
                    Same plane as a BC, but with a Lycoming engine. The BF had a Franklin.

                    Comment


                    • #11
                      Nothing more to add from me. Aeronca41 pretty much covered it all. Welcome to the forum jrd-airco300!
                      A FEW OF MY TOYS !!!

                      MX Linux
                      LinuxMint

                      Miller Roughneck 2E
                      Lincoln Weldpak 100
                      Gianttech Arc 200
                      Victor O/A

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