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Thread: Time to make a knife?

  1. #21
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    I was wondering how to get that cold without liquid nitrogen, cool trick! I can't wait to start on the next one now, with a cryogenic treated blade!
    Spike C
    "The Buddha resides as comfortably in the circuits of a digital computer or the gears of a cycle transmission as he does at the top of a mountain."
    Pirsig

  2. #22
    LN = -300f ish
    dry ice and accatone is about -100f

    some have thought about seening what liquid He would do as its -400f

  3. #23
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    I found this on "simply tool steel .com". Would this apply to O1?

    It is recommended that one thermal temper cycle is performed on the tool before a cryogenic treatment is performed. Since the newly hardened and quenched tool is brittle, tempering prior to cryogenic treatment will reduce the chance of cracking due to stress induced during the process. At least one thermal tempering cycle should follow the cryogenic treatment in order to temper the newly formed martensite resulting from the cryogenic treatment.
    Spike C
    "The Buddha resides as comfortably in the circuits of a digital computer or the gears of a cycle transmission as he does at the top of a mountain."
    Pirsig

  4. #24
    Spike,

    It doesn't do much good to cryo after tempering. Tempering before cryo stablizes the retained austenite and it will not convert to fresh martensite after that.

    The greatest benifit comes from a continuous cool down. Time and tempering cause the austenite to stablize. The steel needs to be subzero quenched within 5 min after the oil quench to get the most benifit.

    Hoss

  5. #25
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    Thanks, Hoss. I don't yet have access to liquid nitrogen figured out, but I see that the acetone/dry ice slurry provides about 50% of the benefit, which is still significant as far as toughness is concerned.
    Spike C
    "The Buddha resides as comfortably in the circuits of a digital computer or the gears of a cycle transmission as he does at the top of a mountain."
    Pirsig

  6. #26
    You will get the full benifit from the dry ice and acetone if you get the knife in there fast enough. With in about 2-3 minutes.

    Hoss

  7. #27
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    Thanks, I can do that!
    Spike C
    "The Buddha resides as comfortably in the circuits of a digital computer or the gears of a cycle transmission as he does at the top of a mountain."
    Pirsig

  8. #28
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    How long should the blade soak in the cryo bath?
    Spike C
    "The Buddha resides as comfortably in the circuits of a digital computer or the gears of a cycle transmission as he does at the top of a mountain."
    Pirsig

  9. #29
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    30 minutes, he said later!
    Spike C
    "The Buddha resides as comfortably in the circuits of a digital computer or the gears of a cycle transmission as he does at the top of a mountain."
    Pirsig

  10. #30
    this thread rocks.

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