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Casting repair

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  • Casting repair

    I have an old aluminum casting (very rare), one of the bolt hole mounting tabs is broken off. I think my best course of action is to repair the missing corner with epoxy built up around an insert for the bolt hole diameter.
    Any suggestions as to the best epoxy to use? The epoxy area would be 3/4" square with a thickness of .250 .
    Non, je ne regrette rien.

  • #2
    Is the aluminum oil soaked? (Has it been around a lot of oil?) I dont think any epoxy will hold to the cast. Nothing to grab on to. Best thing to do would be to make a tab and tig weld it on. Then use a putty to sculpt the exterior to what you want. Alvins Lab Metal would be perfect for this.


    • #3
      How strong does the repair need to be? If "not too strong," the epoxy idea may work. Something metal or glass filled might do it. macona makes a good point about oil though. If you try it, be sure the surface is thoroughly degreased (REALLY degreased) first.

      Brownell's sells a pretty good epoxy, their "Acra-Weld," and I think they sell powdered aluminum to mix into it, but there may be a better choice; I'm no expert on epoxy.
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      • #4
        Chief, I have a whole herd of motorcyles with epoxy type repairs. There's a bunch of engines out in the engine shed that have epoxy repairs to some part of them or another. So far I havent found any of these repairs that hold on for the long term. I have a little pick I use to try them when selling cases, covers or whatever. Any I've tried pry right off with little effort. It probably worked for awhile but a bit of heat and oil seems to doom this type of repair.
        I'm working on one right now. The bottom of a Kawie 80cc motocross bike.
        The case has a big chunk broken out in the bottom. They tried to epoxy it.
        Try tig welding it after an epoxy ain't pretty.
        For this one I'm going to mill all the gunk out with an end mill...bore a small hole in it partway through then tig a plug into the case and machine it to profile. That will last. And's not magnesium. I'd weld that also but you have to be aware.
        I have tools I don't even know I own...