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Difference between Cobalt and Carbide drill bits?

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by WinDancer, Jan 6, 2002.

  1. WinDancer


    May 15, 1999
    Can someone explain the usability difference between Cobalt and Carbide drill bits?


  2. GARY B

    GARY B

    Apr 17, 1999
    Carbide bits can be used to drill already hardened steel. But they are brittle and tend to break if you're not real careful.

    Cobalt bits are the greatest for drilling annealed ready to work steel. They will outlast high speed steel bits four to one so they are worth the little bit extra they cost.

    Hope this helps.
  3. Frank Niro

    Frank Niro Basic Member Basic Member

    Sep 10, 2000
    Well it may not be much but here is a start for you. Cobalt is often added to "regular steel drilling" bits. It does improve cutting abilty considerably. The common amount of cobalt added is usually 8%. Silicon carbide can be a great cutter but is very brittle and is used in bits to drill very hard steels and also in masonary bits. The silicon carbibe bits are usually at least twice or more the cost of regular bits. Lots of care and good cutting fluids with reduced drilling speeds should be used with a reasonable, and controlled amount of pressure. Silicon carbibe drill bits in "true" fractional and numbered sizes also not commonly available. However, properly used in the applications necessary silicon carbide bits will drill very accurate holes. Frank Niro
  4. mpj13


    Oct 5, 2001
    I have used Cobalt bits for drilling 1084 ang 1095. I works fine as long as you use good cutting oil and make sure you don't drill too fast or it will dull the bit and make it really hard to drill anything with it.
  5. Mike G

    Mike G

    Jul 15, 2000
    Never heard of a Silicon Carbide drill bit, and I regrind machine tools on a regular basis!!

    Carbide drill bits, end mills, ect. are all Tungsten Carbide, with a Cobalt binder (W, C, & CO), and are generally whats available.

    Silicon Carbide is used in grinding wheels (green wheels), and in some grinding belts.

    Other than clarifying the make-up of carbide tools, the rest is right on.
  6. Alarion


    Nov 26, 2001
    Titanium carbide or nitride coated bits vs cobalt bits?
  7. Galloglas


    Apr 1, 2001
    ...the cobalt bits are about the best for general knifemaking work. They work well and stay sharper longer on just about any kind of steel I drill.

    The titanium nitrite, high speed steel and such are, to me anyway, pretty much just cobalt wanna bees. They are ok for thin easy to drill stuff but for lasting sharpness and acurate hole drilling use the cobalt.

    A good drill bit sharpener and a cobalt bit will make any drilling job easier.


  8. DrillBoy007


    May 29, 2014
    You might want to check out tungsten carbide, which can keep its sharp edges for a longer period of time:

    source: http://carbidedrillhq.com
  9. PT Doc

    PT Doc

    Dec 24, 2011
    ticker web on cobalt bits might not be ideal in certain situations compared to hss. cobalt bits are m35 & m42: 5 & 8% co respectively.
  10. Huntsman Knife Co.

    Huntsman Knife Co. KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Sep 10, 2010
    Holy thread resurrection batman!
  11. Nathan the Machinist

    Nathan the Machinist KnifeMaker / Machinist / Evil Genius Moderator Knifemaker / Craftsman / Service Provider

    Feb 13, 2007
    Oh my god... this thread... so much fail...
  12. PT Doc

    PT Doc

    Dec 24, 2011
    12 plus year resurrect. Holy cow.
  13. chemistguy


    May 28, 2013
    I see no reason why any sane person would want to drill steel post-HT.
  14. Pelallito


    Nov 9, 2003
    Chemistguy, are knifemakers sane? :)
    Perhaps some one forgot to drill all the holes prior to heat treat?
    That has never happened to anyone on this board, I'm sure. LOL

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