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Thread: Cast Iron (repair)

  1. #21
    Join Date
    Mar 2003
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    I see this every time somebody asks the question. You get fifteen different options, some appropriate, some not. Everyone has their "pet" technique, and often gets indignant when you don't use their specific method.

    The fact is, it's 2019, they actually have workable welding rods for cast iron these days- there's a TIG filler rod I can't recall the name of, and there's a stock-welding rod called Muggy. I've fixed at least six machines with Muggy rod, and it's worked great each time.

    For the small thin stuff, no preheating is needed. Tack, give a short weld, let cool, weld a touch more. It "butters" into clean cast iron almost as well as 6011 lays down on mild steel. So far I've fixed the base casting for my Springfield lathe, the head casting for my Arboga drill press, the "tree" casting for my 'camelback' drill, one of the legs of my horizontal bandsaw, and on the same saw, I basically had to completely rebuild one of the blade-guide clamps:

    Brfore, with a snake pit of both MIG and stick weld...



    After grinding most of that crap off, ndf discovering it was hollow in threre...



    And finally after a lot of digging out of the lo;ld rust and broken metal, and sticking it all back together with Muggy:



    The only drawback being it's kind of expensive at nearly $10 a stick, but when you consider yuou can repair a cat-iron part as easy as you would a mild steel trailer hitch, i my opinion it's worth every penny.

    Doc.
    Doc's Machine. (Probably not what you expect.)

  2. #22
    Join Date
    Sep 2006
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    Southwestern Ontario, Canada
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    Quote Originally Posted by Baz View Post
    How much gap is needed for braze to flow into? I have clean break bit of cast iron that fits back together nicely. If I grind off a bit to make a gap it will need a special jig to align it. The break is through a bolt hole which ideally stays the same size.

    Simple answer is you don't

    Clamp the part down on something in proper alignment

    grind just over halfway through the crack

    braze

    flip it over and grind until you have a nice yellow line though the crack

    braze again let cool slowly under a welding blanket or something like one, dry sand even
    The shortest distance between two points is a circle of infinite diameter.

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

  3. #23
    Join Date
    May 2013
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    UK, near London
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    Thanks, Loose nut.

  4. #24
    Join Date
    Jul 2017
    Location
    Buffalo NY USA
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    315

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    Try this: http://www.locknstitch.com/index.html

    They even offer DIY kits

  5. #25
    Join Date
    Mar 2003
    Location
    Arizona
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    1,067

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    Quote Originally Posted by JRouche View Post
    I dont recommend the glue for that.

    I have brazed a lot of CI and it is the preferred method for an item like that.

    I have also used the TIG method with silicon bronze filler and that is my go to when I need strength and cant fully heat the parts. You do need some preheat either way.

    Neat looking item!! JR
    I've TIG welded quite a bit with silicon bronze rod, even some MIG. Just no experience welding cast iron. This was all welded with silicon bronze.

    https://pbase.com/smokedaddy/image/91623434

    Thanks ...

  6. #26
    Join Date
    Aug 2004
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    Sunny So Cal
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    Quote Originally Posted by Smokedaddy View Post
    I've TIG welded quite a bit with silicon bronze rod, even some MIG. Just no experience welding cast iron. This was all welded with silicon bronze.
    I tell you. I learn something everyday I come to this site. I didnt know it could be used for that also. Nice welds on that project. JR
    My old yahoo group. Bridgeport Mill Group

    https://groups.yahoo.com/neo/groups/...port_mill/info

  7. #27
    Join Date
    Sep 2015
    Location
    NW Illinois
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    729

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    I prefer using O/A with cast iron rod and borax flux. Unfortunately cast iron rod is difficult to find. Several years ago I bought out all of Praxair's remaining stock of cast iron. As I recall it cost about $30/lb.

  8. #28
    Join Date
    Sep 2006
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    Southwestern Ontario, Canada
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    Quote Originally Posted by Smokedaddy View Post
    I've TIG welded quite a bit with silicon bronze rod, even some MIG. Just no experience welding cast iron. This was all welded with silicon bronze.

    https://pbase.com/smokedaddy/image/91623434

    Thanks ...
    The big difference is that cast iron is prone to cracking. When Nirod was the king of cast stick you could only weld about 3/4" and then had to stop and peen the crap out of it, let cool and repeat until the job is done. We would also put the offending part into a charcoal barby-Q and heat to over 400 deg and weld it that way. Some places , maybe with a different alloy would heat to over 1000 deg. It worked, it is cheap but what a pain. The newer rods both tig and stick are much better making cracking much less of a problem but they are EXPENSIVE. The last time we bought some at work was over 20 years ago, made by Exergon out of Texas (great rod), was over $100/lb tig or stick. Worth it if you can afford it. Brazing would still be a better choice.
    The shortest distance between two points is a circle of infinite diameter.

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

  9. #29
    Join Date
    Apr 2007
    Location
    South Texas
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    Brazing or cast iron welding. Both would need to be properly ground, preheat well to stabilize temperature. Brazing would require a good borax flux. Would be strong and durable. Weld with CAT IRON, not that nickle crap. Real cast iron rod would make a nice weld that would also be machinable. Braze would be very strong and relaible and lasting. Proper post weld cooling would be required, simple as placing over a stove burner for an hour, not enough heat to keep the part hot, but to allow the part to cool slowly.

    Use of the Oxy/Acelylene torch is a lost art, but really the best way to make this repair.

  10. #30
    Join Date
    Apr 2017
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    Kelowna BC
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    Nickel city, you or I have totally not got the concept of stitching.
    If a hole was broke out of a piece you can stitch it back in , or a crack.
    But it ain't gonna join two flat pieces together.
    Is the way I see it

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