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Thread: Cast Iron (repair)

  1. #1
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    Default 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. #2
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    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/

  3. #3
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    Quote 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 at 06:33 PM.

  4. #4
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    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.

  5. #5
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    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.

  6. #6
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    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

  7. #7
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    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...

  8. #8
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    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!!!

  9. #9
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    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!

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

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