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  • Cast Iron (repair)

    Do you think JB Weld will work fine to use to put this leg back on the device (vintage Reflecting Goniometer)? I'm trying to avoid welding it if at all possible. The first image below is NOT what I have but just for reference to what what it 'sort of' looks like assembled. The entire device weighs about 60 pounds.







    -JW:

  • #2
    NO. Not for the long hall with that much weight anyway. You could pin it for strength and then use some kind of epoxy like JB weld to hold it together. Why not braze it.
    The shortest distance between two points is a circle of infinite diameter.

    Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

    Southwestern Ontario. Canada

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    • #3
      Originally posted by loose nut View Post
      NO. Not for the long hall with that much weight anyway. You could pin it for strength and then use some kind of epoxy like JB weld to hold it together. Why not braze it.
      I have done a "lot" of of TIG, MIG and stick welding but never welded Cast Iron. I've done a "lot" of brazing on Copper tube (silver solder and Sil-Fos). I've never welded or brazed Cast Iron. Sure would hate to mess it up and/or warp it. Super rare device.

      -JW:
      Last edited by Smokedaddy; 05-14-2019, 06:33 PM.

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      • #4
        Smokedaddy, it sounds like you have the expertise but are just a little wary of doing your first cast iron weld. A little practice on some scrap cast iron pieces is probably all you need to ready you for the real thing.
        Location: Saskatoon, Saskatchewan, Canada

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        • #5
          The leg does not appear to be a precision part as compared to the rest of the device. Either brazing, or pins with epoxy would probably be best.

          I've welded plenty of cast iron with pure Nickel filler, it works well with parameters similar to welding stainless. If you weld it, it would be a good idea to anneal the entire part afterwards -- a charcoal fire is as good as anything. Yes it would warp and yes it would need to be machined. Trying to restrain cast iron against warpage makes the job a whole lot more complicated -- best to just accept warp and machine it out later.

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          • #6
            I had a 1968 Ford PU with a 6 cylinder engine and the exhaust manifold cracked in half.
            I knew a welder who had a superb reputation for welding Cast Iron, Using Nickel rod.
            So I gave him the pieces and he did this. He put firebrick around the perimeter and under the manifold
            and used a steel bar 3 x1 x 24 (?) clamped to the mounting surface for alllignment and "V'd" out some of the joint.
            He heated the entire manifold to 800 F (Said "that" was very important ! )
            Then he welded it with nickel Rod
            When he was done, that manifold was glowing and then he threw a fire blanket ( asbestos?) on top and said to not touch or expose it for 24 hrs.
            The next day I was able to bolt it back on and it fit like a glove without any machining.
            Rich
            Green Bay, WI

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            • #7
              If you don't want to put heat to it then pins and epoxy would be the way to go.
              Drill some oversized holes cut some pins to length fill the holes with epoxy push the pins in and fixture the whole thing together and let it cure.

              I've TIG welding cast iron lots of times, it's not really much different or any more difficult in TIG welding aluminum except when you have really crappy cast iron it has a tendency to just want to burn away,
              You can also use powdered spray weld if you have the torch setup.

              JL...

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              • #8
                I've had great success mig welding cast iron.
                Vee it out, preheat and run your bead.

                THANX RICH
                People say I'm getting crankier as I get older. That's not it. I just find I enjoy annoying people a lot more now. Especially younger people!!!

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                • #9
                  O/A Torch and braze it.Brass will be every bit as strong as the oringinal cast iron and with proper fixturing very little if any warpage will occur.It's my go to for repairs that need to stay straight and machinable are needed.
                  I just need one more tool,just one!

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                  • #10
                    TIG it with silicon bronze.
                    Not low fuming bronze brazing rod.
                    Better heat control and likely less heat input.

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                    • #11
                      "Super rare device." A weld joint would spoil the appearance, braze is better, near invisible.

                      Re pinning & epoxy: how would one drill the 2 pieces to get holes lined up exactly?

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                      • #12
                        Originally posted by Bob Engelhardt View Post
                        "Super rare device." A weld joint would spoil the appearance, braze is better, near invisible.

                        Re pinning & epoxy: how would one drill the 2 pieces to get holes lined up exactly?
                        I would use something like transfer screws to locate the holes between parts. Could have something like a pin with threads on one end, threaded into one part. Locate and drill corresponding holes in the other part. Then stick the parts together with loctite in the holes.

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                        • #13
                          pin and epoxy as suggested PLUS a scab plate hidden on the bottom. That is how i would proceed.

                          Scab plate on top as well would be better yet but spoil the appearance.

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                          • #14
                            Originally posted by wierdscience View Post
                            O/A Torch and braze it.Brass will be every bit as strong as the oringinal cast iron and with proper fixturing very little if any warpage will occur.It's my go to for repairs that need to stay straight and machinable are needed.
                            +1 for this.
                            I have done it severL times with excellent results. Almost invisible.
                            I cut it off twice and it's still too short!

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                            • #15
                              Cast iron welding is a terrible idea to me. I was once working on a broken casting for a professor in my high school machine shop class, a broken foot for a dividing head. I made a new piece, the welding class nickel rodded it back on, and I machined it back. I burnt up two Chinese HSS endmills just getting the job done cutting through the nickel. I came back the next day and the casting had cracked just from the built up stresses. That's anicdotal, and I don't think the students or professor preheated it right. Then again it was a precision part that you wouldn't want to warp. I do think welding has it place, especially for items that go through large heat cycles (like engine components), just not here.

                              I've seen a lot of brazed repairs that have been in service longer than the unbroken tool. I am very comfortable with a proper braze repair, it's nearly if not as strong as the cast. Be it TIG or OA, that's the way to go for general structural repairs. In your case it looks like a great job for a classic OA repair.
                              Last edited by The Metal Butcher; 05-15-2019, 01:44 PM.
                              21" Royersford Excelsior CamelBack Drillpress Restoration
                              1943 Sidney 16x54 Lathe Restoration

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