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93 thunderbolt lead terminal hardware

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  • 93 thunderbolt lead terminal hardware

    Recently got a 1993-1995 Miller Thunderbolt that supposedly spent its life 4 miles from the Pacific ocean.

    Removed the wheels, handle, cover. Don't know if wheel & handlebar is home brew or Miller factory kit.

    There are five lead terminals on the front panel, +/-dc, low amp a.c., high amp a.c., a.c. neutral.

    Two of the cad plated flagged nuts were loose on the terminal assemblies.
    All flange nuts were corroded, but cad plating still covered 100% of surface area and no rust.
    All flange nuts were the automotive type with a serrated flange surface.
    each lead assembly has a brass 1/2"-20 stud, two flange nuts, two cad plated internal lock washers

    question:
    Parts view and list show two nuts and one internal lock washer.
    description for nut: stl slflkg
    according to the acronym online guide, stl = steel, slflkg = self locking

    The flange nuts were not self locking except for maybe the serrated face on the flange might be interrupted as self locking.

    Has anyone removed the hardware on this vintage welder to verify the correct hardware?


    electrical connection in all cases is a square aluminum conductor from either the transformer or choke and flat aluminum strip
    sandwiched between the two nuts and internal lock washers. The lock washers contact the aluminum conductor and nut.

    This is a critical connection since are three metals involved with high current.
    Metals include brass, cadmium, aluminum.

    Suspect the two loose connections were a result of the square aluminum conductor borrowing and being sacrificial to the cadmium plated nut and creating a gap between the nuts.

    on the galvanic chart from top to bottom: zinc, aluminum,steel, brass, ferritic SS, authentic SS.

    electrical path is aluminum conductor to nut to brass stud.
    To protect the aluminum conductor the most, zinc/cadium plated steel is the best choice, because Al & Zn are the closest on the galvanic ladder.

    Seems like serrated finish on the so called self locking flange nuts would not make a good electrical contact with AL conductor.

    Is there a better way to make up this tri metal connection?
    Last edited by Almond farmer; 12-13-2017, 10:29 AM.

  • #2
    I'm guessing that you're not an electrical engineer. So why are you second-guessing Miller's electrical engineers? What exactly are you trying to accomplish, and why?

    I would clean off any corrosion on any of the hardware, coat it with dielectric grease, put it back together and use it, FFS

    Comment


    • #3

      Agree with Helios. You are WAY overthinking this.

      Comment


      • #4
        Helios
        got a four year degree BSEE from UC Berkley in 1970 , Then got multiple degrees in mechanical, spent carrier in applied mechanics.
        electrical not electronics because in 1970 transistors were the size of dimes, but magnetics was big back then.
        did not practice EE at a professional level but did some work for a magnetics device mfgr
        electrical energy transfer through a fastener connection is similar to the physics of heat transfer through contact surfaces,i.e. cast iron sleeve in an engine cylinder. The greater the contact pressure the greater the energy transfer.

        These lead connections are not properly designed,but cost effective.

        purpose,
        looking for a better alternative design

        Obvious maintenance procedure is clean oxide from aluminum conductors with 304 SS wire brush
        clean oxide from brass studs with brass wire brush inside and out, replace electroplated cadmium plated flange nuts
        with new & button it up.
        coating the external connection surfaces with "something" to keep out salt air or condensation might be of benefit for environmental and galvanic corrosion damage.
        would not use dielectric grease on electrical contact surfaces in the current load path.
        Then only have to tighten the end nut to regain contact pressure from the aluminum being permanently compressed from heat generated in the aluminum wire connection.

        could use brass nuts or special made aluminum nuts( easy to machine from 1" hex stock) rather than cad plated steel nuts.

        The best is to have all the hardware including the ends of Al transformer conductors tin plated, as stated in the GE paper.

        Involved with many forums over the last 15 years, this one is one of the best
        Last edited by Almond farmer; 12-14-2017, 10:56 AM.

        Comment


        • #5
          Originally posted by Almond farmer View Post
          would not use dielectric grease on electrical contact surfaces in the current load path.
          Why not? It works just fine on the batteries for cars, boats, etc. It also prevents galvanic corrosion (which seems to be your main concern in this and the other thread) by preventing dew/condensation (electrolyte) from forming between the dissimilar metals. No electrolyte, no galvanic corrosion.

          Comment


          • #6
            Well, whatever it is you do to the guts of that machine, it's not gonna help you pull hot chics. Now if it was a dynasty or even a sncrowave, maybe, but you'd still have to wear a sweet hood.

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            • #7
              Like Olivero's?

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              • #8
                I was going to say your local Miller dealer should have the parts but you might have a better way...Bob
                Bob Wright

                Spool Gun conversion. How To Do It. Below.
                http://www.millerwelds.com/resources...php?albumid=48

                Comment


                • #9

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                  • #10
                    Oh my goodness, Wayne....there is nothing about Oli that will help him pull hot chics. Not even his fancy hood.

                    Comment


                    • #11
                      If anybody would know and/or have unlimited funds and resources to study such things, it would be the USBR. They operate more power plants and substations around the west than most other entities.


                      ""6.1.2.

                      Completely coat the contact sur*

                      faces with

                      a liberal amount of Pentrox "A"

                      or Alnox joint compound.""

                      https://www.usbr.gov/power/data/fist/fist3_3/vol3-3.pdf

                      Or like mac shows, use one of the many 'noalox' versions out there.

                      Torque is critical with anything aluminum. Torque and verify torque.

                      Comment


                      • #12
                        Originally posted by Sandy View Post
                        If anybody would know and/or have unlimited funds and resources to study such things, it would be the USBR. They operate more power plants and substations around the west than most other entities...
                        Funny you say that. I was an inspector with USBR back in 2002 when we founded this forum. I worked throughout the Lower Colorado region mostly with occasional jaunts north.

                        Believe it or not, there are instructions on the bottles of Noalox. They should be read, understood, and followed.
                        Last edited by MAC702; 12-14-2017, 11:42 PM.

                        Comment


                        • #13
                          This is also good stuff, although for your joints containing aluminum the materials mentioned above may be better.

                          https://images-na.ssl-images-amazon....2B2lED8aFL.jpg

                          It puts a "healable" wax coating on metals. Great for electrical connections, distributor cap, etc., in boats.

                          Comment


                          • #14
                            Found the Noalox electrical joint compound at home depot, .5 oz tube, has Zn particles to fill in the matting surface irregularities and seal against environmental oxidation maybe even galvanic corrosion.

                            after studying the linked paper from dept of interior dated 1991 on high power electrical connections, looks like the body of the connector should be Al to reduce sacrificial loss of Al conductor metal from galvanic action on the Al to Brass lead stud.
                            Paper also recommends a split flat washer to take up the gap created by the permanently deformed Al from thermal stress from heat created in the joint.

                            went the specialized fasteners store, only had brass 1/2-20 nuts, no silicon bronze only, 1/2-13
                            after studying the DOI paper discovered copper or brass nuts was a bad idea.

                            new plan
                            order 1ft length of 1" hex Al bar and 1ft, 1/2"dia copper rod from McMaster Carr
                            make two 1/2"-20 nuts to replace steel nuts
                            Drill hole in rod to fit welding lead straight brass male connector, Thread copper rod , 1/2"-20, cut off 3"
                            Assemble the connector with Noalox & 1/2" Al split lock washer

                            The two steel flange nuts make no sense , very high resistivity, when is the last time seeing a steel truck battery lug.
                            The original flange nuts have a serrated finish, not the best for electrical contact.
                            Electrical load path is through the nut from Al square cross o SS section conductor and/or flats Al strip to the threaded stud

                            Comment


                            • #15
                              Originally posted by Almond farmer View Post
                              new plan
                              order 1ft length of 1" hex Al bar and 1ft, 1/2"dia copper rod from McMaster Carr
                              make two 1/2"-20 nuts to replace steel nuts
                              Drill hole in rod to fit welding lead straight brass male connector, Thread copper rod , 1/2"-20, cut off 3"
                              Assemble the connector with Noalox & 1/2" Al split lock washer
                              Click image for larger version

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                              Originally posted by Almond farmer View Post
                              The two steel flange nuts make no sense , very high resistivity, when is the last time seeing a steel truck battery lug.
                              Well, at least now we know why those millions of Thunderbolts that Miller has made over the past 40 years don't work!

                              Comment

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