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  • New work (ground) clamp(s)

    In a thread some time back, I stated that if I found a good price (sale) on the all copper 300 amp Hobart work clamp (Part #770029), I'd buy one. Walked into my local Northern hardware the other day and found them for $9.99, so I bought two. (I'm not real impressed with the work clamp I put on my stickmate. It was a demo with no stinger or work clamp for $200.) This seems to be a nice heavy spring and thick stamping at half the cost of the brass ones. Got some personal obligations that may delay testing, but I've installed them and will try them out.
    Blacksmith
    Stickmate LX AC/DC
    Big cheap (Chinese) Anvil
    Hand cranked coal forge
    Freon bottle propane forge
    HH 210 and bottle of C25

  • #2
    TWECO has one with copper contacts at the business end for about $13.

    http://store.cyberweld.com/groundclamp300.html
    --- RJL ----------------------------------------------

    Ordinarily I'm insane, but I have lucid moments when I'm merely stupid.
    -------------------------

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    • #3
      Ground Clamps

      What material is best for a ground clamp when MIG welding? What does everyone think of the magnetic ground clamps?
      Thanks for your opinion

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      • #4
        Originally posted by Oltmanjt View Post
        What material is best for a ground clamp when MIG welding? What does everyone think of the magnetic ground clamps?
        Thanks for your opinion
        Don't know a single experienced weldor (out of hundreds) who used them, and copper or bronze/ brass is the best common welding conductor.

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        • #5
          Copper is more conductive than brass or bronze by a wide margin. We can't afford silver contacts, so copper is it.
          --- RJL ----------------------------------------------

          Ordinarily I'm insane, but I have lucid moments when I'm merely stupid.
          -------------------------

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          • #6
            Welding invariably produces spatter and other magnetic particles that get attrected to the magnetic work clamps and lesson their grip and electrical conductivity with use. Just look at any magnetic welding angle clamp to see the collection of debris. I'm not an experienced welder, but after cleaning my work, I don't mind "grinding" my work clamp into the piece a little to ensure good contact. Can't do that with a magnet.
            Blacksmith
            Stickmate LX AC/DC
            Big cheap (Chinese) Anvil
            Hand cranked coal forge
            Freon bottle propane forge
            HH 210 and bottle of C25

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            • #7
              These might be worth taking a chance on.

              http://www.ebay.com/itm/200616292818...84.m1423.l2648

              It has a copper braided cable between the two jaws. Something you want on this style of clamp.
              Last edited by Scott V; 03-03-2012, 04:59 PM.

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              • #8
                Unless they are just copper plated, that is a **** of a deal.
                --- RJL ----------------------------------------------

                Ordinarily I'm insane, but I have lucid moments when I'm merely stupid.
                -------------------------

                Comment


                • #9
                  Right, but it said copper in the ad. I will find out, I ordered two. They combine shipping, so could be a good deal.

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                  • #10
                    Originally posted by usmcpop View Post
                    Copper is more conductive than brass or bronze by a wide margin. We can't afford silver contacts, so copper is it.
                    In fact, copper isn't really it, since by a wide margin, the majority of electrical contacts in most welding circuits are brass, not copper. (Look at the other end of your cables). Also, copper is used only as plating on most static contacts and brass or steel is carrying the majority of the conductive load. In addition, if you look at pipeline work, you will find wide use of "grasshoppers", which are often all steel grounding devices. Finally, this difference in conductivity is so negligible in a welding circuit, that if you substituted a pure copper pad for a brass one on a ground clamp, I don't think you would be able to detect the voltage drop or resistance change with an ordinary VOM.

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                    • #11
                      In reality, copper strikes a nice balance between cost, corrosion resistance and conductivity. Hence it's widespread use in wiring. I agree that the clamps I just bought are copper plated steel according to the Hobart catalog, but they are nice and shiny and I am a bit like a crow in that respect; "ooh shiny!" If I think they work better, and they probably do, the contact area and spring force on these is much higher than the 99 cent clamp that came with my 210, maybe I'll weld better.
                      Last edited by Blacksmith; 03-04-2012, 08:40 AM.
                      Blacksmith
                      Stickmate LX AC/DC
                      Big cheap (Chinese) Anvil
                      Hand cranked coal forge
                      Freon bottle propane forge
                      HH 210 and bottle of C25

                      Comment


                      • #12
                        There's a relative scale of conductivity based on pure Copper being 100% (%IACS). Some various metals:

                        Silver: 105 %
                        Copper: 100%
                        Gold: 72%
                        Aluminum: 62%
                        Zinc: 29%
                        Nickel: 27%
                        Iron: 17%

                        Copper is alloyed to improve strength and, in electrical applications, to increase the recrystallization temperature and creep strength. Adding .05-.15% Silver reduces conductivity slightly but improves the mechanical properties. Adding different things can markedly affect electrical conductivity, and thermal conductivity tends to follow.

                        Copper-Nickle (70/30): 5%
                        Deoxidized Copper: 75-85%
                        Silicon Bronze: 7%-12%
                        Phosphor Bronze: 11-48%
                        Red Brass: 37%
                        Naval Brass and 360 Brass: 26%

                        It may not make a lot of difference, but I'd rather have a soft copper pad that is relatively corrosion resistant than a steel contact. Brass is OK.

                        http://books.google.com/books?id=sxkPJzmkhnUC&pg=PA297

                        http://books.google.com/books?id=RzMOiOEQ-oMC&pg=PA110
                        --- RJL ----------------------------------------------

                        Ordinarily I'm insane, but I have lucid moments when I'm merely stupid.
                        -------------------------

                        Comment


                        • #13
                          Golly, a month or two ago I said I'd buy the Hobart clamps at the right price, found what I thought was a good deal (TSC lists them for $3 more) and reported same. I seem to have set off an argument almost as heated as Edison (DC) versus Westinghouse (AC)!
                          Blacksmith
                          Stickmate LX AC/DC
                          Big cheap (Chinese) Anvil
                          Hand cranked coal forge
                          Freon bottle propane forge
                          HH 210 and bottle of C25

                          Comment


                          • #14
                            Just to add to usmcpop's info.

                            Contains specific wording as to brass.

                            http://www.kp44.org/ftp/ElectricalCo...fMaterials.php

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                            • #15
                              Originally posted by Sandy View Post
                              Just to add to usmcpop's info.

                              Contains specific wording as to brass.

                              http://www.kp44.org/ftp/ElectricalCo...fMaterials.php
                              This is all interesting as it applies to wiring, cabling , and transformer manufacturing, but my point was that very little of the CONTACT material in a welding circuit is copper, and much is brass, copper-plate or steel. Also, frequently, by necessity on a large structure, there are feet of steel between the ground clamp and the electrode, and, other than turning up the heat a bit, few of us worry.
                              Last edited by Northweldor; 03-04-2012, 08:07 PM.

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