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Grit progression pre/post HT

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by Bordergraver, Sep 16, 2019.

  1. Bordergraver

    Bordergraver

    7
    Jul 31, 2019
    Newbie question. This has probably been discussed before but I can't seem to find exactly what I need so I'll ask. Can someone give me some suggestions on what grit to take the grind to before HT, and then where to pick back up post HT? For what it's worth, I am working with AEB-l and CPM154, foil wrapped and oven treated, and then plate quenched. I assumed I could take the edge down to about .020 and any grinding after HT would be to just remove any possible decarb and get to a desired finish, but I am confused as to why some have posted dropping back down a few grits after HT. Also, the belts I just ordered and will be working with include the following, all from Combat Abrassives: 40, 80 ceramic, 120 zirconia, 220 AO, 400, 800 structured and a fine surface conditioning belt. Any advice on grit progressions and edge thickness prior to and after HT using what I have for belts would be greatly appreciated!

    TJ
     
  2. Rhinoknives1

    Rhinoknives1 KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jul 1, 2013
    Your progression of 40,80 120 Etc should work providing you bought good belts. I do all of my grinding post HT . I use VSM Ceramic, 36, 60, 120 and then use Scotchbrite & cork belts. I use to go to 220 before HT and then 120 and up after. You drop down to catch any scratches you missed before HT. I’ve found you get a Smear before HT & a crisp Grind after HT. Got tired of doing it twice. The VSM Ceramic dont last as long as blaze. But they are half or less the cost.. and I only use about 50-60% of the grit. Then the create too much heat so they go to the profiling etc pile. Stay safe & Have Fun..
     
  3. AVigil

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

    Feb 17, 2009
    What style of knives are you making?

    On my folder blades I grind post heat treat.

    On my tantos I take them to about 50% bevels to insure there is a large flat for plate quench.
     
  4. Bordergraver

    Bordergraver

    7
    Jul 31, 2019
    Thanks for the response. I'm gonna make a few drop point hunters out of 5/32 stock. I'm gonna do a couple with flat saber grinds and a couple hollow grinds.
     
  5. Bordergraver

    Bordergraver

    7
    Jul 31, 2019
    Sorry I missed your response somehow. So assuming you are confident you didnt miss any scratches before HT, then there is no reason to drop down a grit? I guess I'm just worried about messing up my temper due to lack of experience and am trying to avoid doing anymore grinding than necessary. So out of curiosity, do you grind after fully tempering the knife, or prior to temper?
     
  6. J. Keeton

    J. Keeton Basic Member Basic Member

    723
    Nov 15, 2005
    ckdexterhaven likes this.
  7. coldsteelburns

    coldsteelburns

    Aug 2, 2010

    I enjoy working with carbon steels, so if I'm doing any grinding before HT I'll take it up (or down) to 220 grit and grind somewhere around 50% of the bevels with the edge around 30 thousandth to bring the blade to a wedge cross section, especially for clay hardening. After HT including the temper cycles, I'll go back to 60 or 80 grit, not for cleaning up scratches but in order to finish grinding in the bevels and refine edge geometry. Then I go to 120 ceramic, 220 (either ceramic or Klingspor J-flex AO depending on what I have), then either cork or gators before handing sanding, which is usually only around 400 or 600 if I'm not etching and polishing out a hamon. Not sure if that helps, but it's what I do :)


    ~Paul
    My Youtube Channel
    ... (Some older videos of some of the earlier knives I've made)
     
  8. Bordergraver

    Bordergraver

    7
    Jul 31, 2019
    Thanks gents for the replys! Thats definately been helpful. I think I'm just gonna have to make a few using a couple different methods and find out what works the best for me. Seems like most things, everyone has their way, and no one really does it the same.
     
  9. Busto

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

    Jul 26, 2011
    For each Custom Handmade Makers Knife they follow certain basic steps to reach the final product. Certain Steels by size and design work easier Pre or Post heat treat this is where taking notes and figuring out what works best in Your shop...This is what separates Individual Handmade Knives from Factory Assembly line Made Knives. It's been my experience that when asked 100 knife makers have 100 different answers...
     
    Jason Volkert likes this.
  10. argel55

    argel55

    Oct 30, 2005
    The CPM won't matter but you are better off grinding AEBL after heat treat to prevent warpage.
     
  11. Maelstrom78

    Maelstrom78

    Sep 21, 2013
    With the VSM ( I also grind post HT ) I don't feel bad grabbing a new 60 grit after a little initial hogging with a 36.

    New fresh belt on every blade!!
     
    Rhinoknives1 likes this.
  12. Horsewright

    Horsewright KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Oct 4, 2011
    I'd agree, everyone seems to have their own deal that works for them on their outfit. On all AEB-L stock under .100 I grind post ht. .100 and thicker I grind pre ht. The pre ht ones I take to about 85% done and then finish the rest after ht. I go from 36 grit to 50 to 120 (BVC) then use an A/O 220 and finish with a green Scotchbrite. On blades ground prior to ht I go up to 120 and then start with a 50 after ht.
     
    Rhinoknives1 and J. Keeton like this.

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