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Bending cast aluminum. HOW!! Please help!!!!

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  • Bending cast aluminum. HOW!! Please help!!!!

    I'm getting to the end of rebuilding a small Rotex mill and I noticed that the vert. head casting was bent so that the motor on the back is a little less than a 1/4 lower the the front of the head. The casting has a very fine crack in the back mounting area where it mounts to the front arm ( the bright belt cover is what I'm talking about) Here is a link to the Rotex mill.
    http://www.lathes.co.uk/rotex/
    What is the best way to get it bent back to level? If I can get it back to level I will tig weld some ribs to make it stronger. Should I heat it first or what? I know nothing about this.

    Thanks in advance for any and all help!!!
    Dan

  • #2
    Dan,

    While I am no expert in this matter...

    Cast aluminum is very crack happy !

    Bending this is a risky idea as it may crack or break.

    As far as welding... hmmm if is a REAL HIGH QUALITY cast then it may be weldable... the problem is that cast aluminum usually has a kinds of crud in it that make it an unfriendly task to take on.

    Your idea of preheating is right on though... anytime you need to weld aluminum on a large scale preheating is a good idea!

    Good luck! I hope that someone here has something more worth while to offer you!

    ebob

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    • #3
      Dan

      Chances are it is made from the same aluminum used for transmission cases - as such it could be a total bitch to weld. You an try repairing it, but you will have to make sure the casting is completely dry (preheat in oven at 450 for a few hours). You will need to grind the crack away so you can fill it with fresh metal. Once welded put it back in the oven and turn the oven off and let cool.

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      • #4
        Thrud,

        Will heating the part make it easy to bend? If so how hot? If I make some ribs what type of Al. should I use?
        Thanks Again-Dan

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        • #5
          Cast aluminum as a rule bends like rock - not very well. It really depends on the alloy that it was cast with. If it was cast with 1xxx, 2xxx, 6xxx it may bend fine. Other than that I can't help you brother.

          Heat won't help, the preheating is for getting a solid weld. Grind all of the crack out after you bend it, preheat, weld, let cool. Make the ribs from 6061 if you have some and bevel the bases so you get good root passes.

          [This message has been edited by Thrud (edited 01-14-2003).]

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          • #6
            I read somewhere that to bend aluminum you cool it, way cold. This is done, I believe, with rims that have been dented. Cool it, then hammer the metal back to shape. Recool as required until all reforming is done. I don't know what cast would respond like, but I think preheating before bending it is likely to make it crack easier.
            I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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