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Reheat treating a folder blade/s35vn

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by rodriguez7, Aug 28, 2019.

  1. rodriguez7

    rodriguez7 Gila wilderness knife works Knifemaker / Craftsman / Service Provider

    Feb 1, 2009
    So, I have a hinderer Bowie in s35, that tested really low rc, so I’m wanting to reheat treat it. Looking for 60-61 rc. Sadly it tested out around 57rc. Disappointing. The heat treat I think I have down, 1950 aus, x40 minute soak, plate quench, cryo overnight, triple temper around 400. My main concern is the press fit thumb studs. I’m wondering if I’ll have a fracture on the blade, or if the actual thumb studs will fracture. Anyone have any ideas? Thanks.
     
  2. daizee

    daizee KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Dec 30, 2009
    I'd get those thumb studs out so you can plate-quench it, no?
    40min soak sounds excessive to me, but maybe necessary for already-hardened?

    Yeah, 57Rc is really low for S35VN, especially in a folder.
     
  3. Bob Ohlemann

    Bob Ohlemann KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Dec 5, 2013
    How are you going to plate quench a knife that has the bevels finished? The Crucible data sheet says you can do an interrupted oil quench down to 1000 degrees and then plate quench but, I still think that is going to lead to a soft edge and probably warpage. Additionally, S35VN does not need 40 minutes at temp; I use 20.

    57 might be a little low for S35VN but, it is useable. I have a feeling it won't be a useable knife after you re-heat treat it.

    Bob
    Edited to add: If this is a folder (I'm not up on Hinderer knives but, I thought their bowie was a fixed blade), you can forget it. Heat makes metal move. You will disrupt your pivot, stop points and your lockup...and, as you mention probably the thumbstud. It makes far more sense to just reblade it and set the original blade aside so you could return it to stock later.
     
    Last edited: Aug 28, 2019
    seanj and AVigil like this.
  4. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    Rc57 was considered high for a commercial folder for nearly a century. It is only recently that people want folders in the Rc 60 range. You will likely ruin the blade if you attempt to re-do the HT. For one, it won't be the same side and thickness after HT and clean up.
     
  5. Busto

    Busto KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jul 26, 2011
    I think Bob's suggestion is spot on to Reblade makes more sense. Commercial knives often come in lower RC than expected which cuts down on warranty claims for high RC snapped blades.
     
  6. razor-edge-knives

    razor-edge-knives Moderator Moderator Knifemaker / Craftsman / Service Provider

    Apr 3, 2011
    My main concern is warping so it may not be centered after the ht.
     
  7. daizee

    daizee KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Dec 30, 2009
    Yeah, I have to agree about starting fresh. You'll have exactly all of the same problems, but with more material to work with and you won't have wrecked the original part.
     
  8. DevinT

    DevinT KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jan 29, 2010
    Just sell it.

    Hoss
     
    shqxk and Jason Volkert like this.
  9. JTknives

    JTknives Blade Heat Treating www.jarodtodd.com Knifemaker / Craftsman / Service Provider

    Jun 11, 2006
    Normally factory folders are ran a tad soft. But the spiderco farid K2 In CPM10V is quite hard. I’m not sure you could get much more performance out of it.
     
  10. Natlek

    Natlek

    Jun 9, 2015
    Do you suggest to HT stainless steel blade before bevels are grinded ?
     
  11. Bob Ohlemann

    Bob Ohlemann KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Dec 5, 2013
    Absolutely. It makes no sense to plate quench an air hardening steel if you can't get full contact with the surface.

    Bob
     
    AVigil and Jason Volkert like this.
  12. Natlek

    Natlek

    Jun 9, 2015
    Thanks ! Make sense ... thin edge have no contact with plate +will draw heat from thick spine all time and will cool down last ........ + you can check hardness where it matters.....on edge . But most knifemaker here HT stainless with bevel already grinded , almost to final thickness ...............at least that is what I read here as suggestion .
     
  13. bmilleker

    bmilleker Gold Member Gold Member

    365
    Nov 26, 2012
    The trend I am seeing is more and more makers grinding hard.
     
  14. JTknives

    JTknives Blade Heat Treating www.jarodtodd.com Knifemaker / Craftsman / Service Provider

    Jun 11, 2006
    We rarely get blades that are ground. And when thy are ground it’s usually just a short edge bevel that knocks the corner down.
     
  15. AVigil

    AVigil Adam Vigil knifemaker working the grind Knifemaker / Craftsman / Service Provider Platinum Member

    Feb 17, 2009
    On small blades I grind post heat treat, but on large fighters and Bowies made in 3v or Z finit I take it to almost a finished grind as do many other makers.
     
    rodriguez7 likes this.
  16. shqxk

    shqxk

    Mar 26, 2012
    Not worth the risking with even the slight warpage.
     
    DevinT likes this.
  17. rodriguez7

    rodriguez7 Gila wilderness knife works Knifemaker / Craftsman / Service Provider

    Feb 1, 2009
    This is what I’ve been doing, and I have had no problems. I grind to almost finish, because when plate quenching, the heat get sucked out of the thin edge anyway. So it makes no difference, and fully hardens anyway. But thanks everyone. I guess I’ll avoid trying it, and just stick with what I have.
     

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