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"No-PreHeat" Cast Iron Repair Technique

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  • aametalmaster
    replied
    I have seen their vid and even some repaired work but the lockstitch can't be used in every repair job because of how the parts broke or the cost so we have to do it the new old fashioned way I just did a 20 thousand dollar hyd pump case where the ears were broke off and welding was the only way...Bob

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  • MR.57
    replied
    Lock-n-stitch put together some good information explaining expansion and contraction and made it freely available. I have made many cast iron weld repairs in my career and no matter what process you choose, understanding how the part expands and contracts is essential if you want the repair to be anywhere near as strong as original.

    At first I thought the video was going to be an ad for their product, but they do not make a single mention of Lock-n-stitch pins throught the entire demonstration. It does however, provide an excellent visual illustration of what's going on when you heat a casting unevenly. I'd consider them an authority on cast iron repairs and they do a nicer job than I can of explaining what's the main problem with making repair welds on non-preheated cast iron. Watch to the end, it's boring at first but gets more interesting towards the end.

    Here's a link to the page with the video:
    http://www.locknstitch.com/CastIronWelding.htm

    (Click on "Cast Iron will obey the laws of physics, even if you don't know them" at the bottom)

    In my opinion, the only way to get a perfect cast iron repair is to do it the old fashioned way which involves heating the entire part to critical temp and welding with cast iron rod and then slow cooling the entire part. Peening or not, any other method is going to leave a lot of residual stress in the casting which can lead to cracking.

    Of course we all know that not every repair needs to be perfect, sometimes "good enough" is just that, good enough.

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  • aametalmaster
    replied
    Thats the hardest part is getting the junk out of the crack. A torch works the best if there is no other way like with solvents...Bob

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  • aaronobrien
    replied
    When doing a repair like this (ie: transmission, gear housing, etc.) what do you use to prep/clean the weld area? What if you cannot get to the backside to scrub...???

    A year or so ago I had a pump from a crane needing to be welded, but I always got crap in the weld, no matter what I did the the top (area of weld) to claen it, so i assume that the contamination came from the backside.

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  • Portable Welder
    replied
    Weld On Welding, I have often thought of trying silicon bronze but never have.

    I have been using a good old oxy/ acyt. torch for years with great success, However when its a chunk of cast that is to big for the gas grill ( Engine block )

    I have resorted to using a crown product called 55/45 with tig and do it cold, I have also arc welded it cold.

    Plain and simple there are more than one way to skin a cat.

    Now when I say cold, That doesnt mean no heat, I still warm the area as much as possible without melting wires.

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  • Sandy
    replied
    Originally posted by aametalmaster View Post
    Nope no problem. I really don't have a meter just taps so i just play it by the job...Bob
    Good deal, thanks.

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  • aametalmaster
    replied
    Originally posted by Sandy View Post
    I see that Crown Alloys 44-30 specs out some pretty high voltage. Have you found that to be a problem at all?
    Nope no problem. I really don't have a meter just taps so i just play it by the job...Bob

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  • HomerJSapien
    replied
    Lanse, another good video. It's expecially nice to see one WITHOUT all the commercial interruptions! Thanks...

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  • harold
    replied
    Cast iron welding

    I'm sure there are many good ways to weld cast iron; last fall when I need to repair a set of old cast iron stove legs I asked for some suggestions. Recieved a lot of informative suggestions. Bob (aametalmaster) suggested crown alloy 44-30 and mig. Had a problem locating the wire in a small size spool but ultimately found it; all I can say is wow what a surprise. welded the crack, welded in the broken piece and cut up an old frying pan to make a missing piece. Really looked like new. Much belated but many thanks Bob great suggestion and wonderful advice. The peaple who's camp it went to in the Adirondacks were extremly pleased also.

    Harold

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  • Sandy
    replied
    Originally posted by aametalmaster View Post
    Prob 90% of my cast repair now is with a mig and Crown Alloys 44-30 cast iron mig wire. I can do repairs that a few years ago i just dreamed about. Here is a tractor manifold i fixed for my neighbor. Yes i know a new one is only 39 bucks but i wanted to try out the wire. I welded it cold with the mig building up the bad area and he filed it to suit. He said the tractor has never been so quiet. I welded a BB Chevy for a guy 2 states away and he drove the block to me to fix. The repair took 15 minutes and he drove 11 hours to get it to me...Bob
    I see that Crown Alloys 44-30 specs out some pretty high voltage. Have you found that to be a problem at all?

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  • weldonwelding
    replied
    I have tried the utp 55, and 99. And lots of other techniques. The very best I have found that I always use is tig weld silicon bronze. Its a bit too hard to drill but if your just repairing cracks...try it. I guarantee you'll never use anything else

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  • kevin
    replied
    the most important thing this gentleman mentioned is the back stepping technique, one should always weld in the direction of weld that is cooling, not the opposite, a weld that is building heat, this technique works great on long butt welds

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  • aametalmaster
    replied
    Prob 90% of my cast repair now is with a mig and Crown Alloys 44-30 cast iron mig wire. I can do repairs that a few years ago i just dreamed about. Here is a tractor manifold i fixed for my neighbor. Yes i know a new one is only 39 bucks but i wanted to try out the wire. I welded it cold with the mig building up the bad area and he filed it to suit. He said the tractor has never been so quiet. I welded a BB Chevy for a guy 2 states away and he drove the block to me to fix. The repair took 15 minutes and he drove 11 hours to get it to me...Bob
    Attached Files

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  • jrscgsr
    replied
    There was a fantastic video on YouTube on the topic that demonstrated the problem with trying to weld a constrained cast iron crack. The proper way to fix one is to dril tap and pin the crack with overlapped threaded "pins"

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  • jrscgsr
    replied
    Cast iron cracks, especially on something like a cast iron engine block because the material around the weld is constrained. When the weld is made the material is superheated and expands (you can't weld it cold, your arc is around 2500 degrees) this expanding material has no where to grow so instead the material thickens, as it cools back down the thickened material tries to go back its original shape and pulls the surrounding material causing a crack.

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