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Recommendation? Drilling harden steel from 1/8 up to 3/16"

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by AVigil, Jun 27, 2019.

  1. AVigil

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

    Feb 17, 2009
    I have a couple of harden Aebl slipjoint blades with an 1/8" hole for the pivot I want to bring up to 3/16".

    I have a carbide reamer for the final 3/16" for the bushing.

    What carbide drill sizes would you recommend going from an 1/8" to just before using the reamer?
     
  2. HSC ///

    HSC /// KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Nov 7, 2012
    I use a #14 carbide drill.
    A heavy rigid setup is the key for this drill operation
    When I ream I generally slow the spindle speed down 60% or more and use cutting oil.

    also you may find the 3/16" reamer gives you an undersized hole...so if you are using some precise bushing or whatever you may want to mic that. I've started to use a barrel lap to get my final size.
     
  3. AVigil

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

    Feb 17, 2009
    You would go from the 1/8" directly to the #14 ?

    I have a barrel lap
     
  4. HSC ///

    HSC /// KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Nov 7, 2012
    yes, I've done it several times.
    I have a Bridgeport mill so the setup is heavy and rigid.
    Best thing to do is try it on some hardened AEB-L scrap (if you have some).

    But there's no need to setup up incrementally in drill sizes to make a hole ( that I know of) I suppose if your setup is weak then you could try an intermediate drill, but if it's not a rigid setup then the carbide tool will just break anyway,

    If you have any concerns about the squareness of the hole (perpendicularity) then you could plunge mill it with a something like a 5/32" carbide 4 flute bottom cutting end mill first.
     
    AVigil likes this.
  5. AVigil

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

    Feb 17, 2009
    Thanks,

    Have a #14 carbide drill bit coming.
     
  6. kuraki

    kuraki Fimbulvetr Knifeworks

    Jun 17, 2016
    Stepping up in this case could be detrimental to your cutting tools anyway. Easy to break the corners off the edge of the drill if the depth of cut is too small.
     
    AVigil likes this.
  7. butcher_block

    butcher_block KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Dec 6, 2004
    normaly i liek to use 4 flute ball ens mills in carbide on hardened steel but latly i have underrsized drill pre HT then ream to size post HT. i really need to get myself a set of carbid under over reamers
     
    AVigil likes this.
  8. AVigil

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

    Feb 17, 2009
    Thanks for the advice.

    I drilled out the 1/8" pivot hole with #14 carbide bit on my mini mill with cutting fluid. The blade was clamped down on a jig and mounted in my vise.

    Followed up with a 3/16" reamer then with a barrel lap.
    The bushing slide in perfectly .

    [​IMG]

    [​IMG]
     
    Busto, HSC /// and Rhinoknives1 like this.

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