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heat treat with auto trans oil

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  • heat treat with auto trans oil

    I need to extend a 1/4 inch belt support rod on my DR Trimmer that has worn away due to the trimmers drive belt riding it, the repair will need to be heat treated.

    I remember reading that a certain brand of automatic transmission fluid can harden steel but i can't remember what brand it was. Do any of you guys know, thanks?

  • #2
    Never heard of that... Interesting though.


    • #3
      you can case harden the piece by heating to 1600 0f and wraping in a leather glove or some other material that has a high carbon content, the carbon from the glove will be soaked into the shaft making the outer edge wear resistant.


      • #4
        I think the oil trick is where a piece of tool steel is fully hardened and then brought down to spring hardness by a coat of oil which is set on fire. When it burns off the metal is at spring hardness. probably only works on small parts like springs. Your application may be better with a piece that has been case-hardened. Saw somewhere to case-harden, put a piece of metal in a metal can packed with pieces of leather or bones and then throw in the fireplace with a big fire. The carbon in the leather/bones is slowly absorbed into the steel, making the outer skin hi-carbon steel and it should be somewhat harder. It takes a few hours to do its thing, just take it out in the morning. There is also a product out there, Kasenit I think, where a piece of mild steel is heated red and then dipped into this powder to case-harden. Used in the gunsmith industry to harden small parts. Good luck


        • #5

          Generally hardening is achieved with some sort of heat treatment followed by quenching. The speed at which you quench the material, directly affects how hard the steel will be in the end. Water cools down steel very quickly which in turn will give you a very hard object that won't be very ductile, ie it will break if struck or made to bend. Oil absorbs heat energy more slowly than water so the quench will be slower, sacrificing a little hardness but gaining more ductility in the process. The problem with using oil to quench is that it can catch on fire, as far as I know there are some oils with very high flash points so this may be avoided, but never the less I would be keeping the fire extinguisher handy!!

          There are a few other things that you can do to work out temperature elevations etc. but that is really involved.
          "Its the way it spatters that matters!"


          • #6
            Hardening Metal

            Tackit I have used this product over the years with good sucess.
            Heres their address; phone number and website.
            Good luck with your project.

            The Rose Mill Company
            122 Park Avenue
            East Hartford, CT 06108
            860.289.4098 ph
            [email protected]



            • #7
              Low carbon steel can not be hardened by heating to critical temp and quenching. only steel that is above .3% carbon can be hardened by quenching.


              • #8
                Thanks guys for all the suggestions, I will have to do some experimenting with a 4 inch long 1/4" grade 8 bolt.

                I also have heard if you take a lawn mower motor and adjust the carburetor to a rich setting and run it's exhaust into a box with the heated part it will harden steel too.