Toolsteel heat treat and small hole shrinkage?

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  • wierdscience
    Senior Member
    • Jan 2003
    • 22085

    Toolsteel heat treat and small hole shrinkage?

    Got a project I want to build that involves several plates,dies basically with small threaded holes in them (#2-#10)that must be heat treated.

    I've never heat treated anything with tapped holes that small before.How much if any shrink should I expect in either O-1 or A-2?

    Also would plugging the holes with some soft althread help keep the thread crests crisp?
    I just need one more tool,just one!
  • Rich Carlstedt
    Senior Member
    • Jul 2001
    • 5482

    #2
    Weird
    We always asked the heat treater about shrinkage when doing HT (heat Treat)for smaller parts.
    Generally you can go with a Class GH-5 ( ground high -5 fit) which as I recall is about .001 to .002 over a standard tap. never had a problem with that
    Shrink and "warpage" occur, so long thread holes may be a problem ....like 2 + inches for example
    Don't worry about it being too big, the H.T. makes the steel stronger.
    We always put sacraficial (unplated ) screws in a blind hole, as you commented on.
    Rich
    Green Bay, WI

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    • fishfrnzy
      Senior Member
      • Oct 2005
      • 285

      #3
      Can't find the resource at the moment but from memory the A2 should be better and I think the distortion is in the 1% or less range.

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      • Toolguy
        Senior Member
        • Jan 2010
        • 6666

        #4
        Tool Steel

        As a general rule, the air hardening steels have less distortion than those that are quenched in a liquid. For what you are doing, you shouldn't have any problems either way.
        Kansas City area

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        • wierdscience
          Senior Member
          • Jan 2003
          • 22085

          #5
          Thanks for the replys.Okay I am going with A-2,easier to treat anyway.

          The crossection is only going to be 1/4" at the widest point,so distortion over the length won't be an issue.

          I may try tapping the holes in a sample first,if they still thread good,if not I know H5 taps are in my future.
          I just need one more tool,just one!

          Comment

          • Juergenwt
            Senior Member
            • Sep 2010
            • 371

            #6
            A-2 Small holes - No change.
            O-1 Small holes - No change to slightly larger.
            In general - Tool steel like O-1 will shrink on the outer dim. and holes will open up.
            Air hardening tool steel - very little change.

            CRS will grow on the outer dim. and holes will shrink. How much depends on how much case is asked for.
            Last edited by Juergenwt; 10-15-2010, 02:12 PM.

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