Drill Bits For Drilling Harder Metals

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What are cobalt bits


Cobalt drill bits are drill bits which contain a percentage of cobalt. The two most commom percentages are 5% (also known as M35 ) and 8% (known as M42 )


The more cobalt a drill bit contains the harder the metal you will be able to drill however, the increase in cobalt has a downside in that it makes the drill bit more brittle.


Best metal drill bits 


If you are using a hand drill then 5% cobalt bits are probably the best drill bits for you as they will certainly drill most hard metals you will encounter including stainless steel.


However if you are drilling in a very controlled fashion using a pedestal drill with variable speed controls and you are drilling a very difficult metal 8% may be a better option. However even under controlled drilling you will have the increased chance of breaking the bit.

 best drill bit sets reviewed by builder Aaron Barnett


Which bits for metal?


If you are drilling metal, particularly harder metals such as stainless steel you will probably be advised to use M35 bits.


The addition of cobalt has 3 main positive impacts on a drill bit.


  1. First of all it increases the red hardness of the drill bit. This is basically the drill bits ability to withstand high temperatures.
  2. Due to its hard nature it increases the abrasion resistance of the drill bit.
  3. Finally a cobalt drill bit can be resharpened.


Drilling hardened steel


TTP HARD  drill bits are 5% cobalt throughout. This means they can be sharpened and will drill through hard metals including stainless steel.


Our bits have been tested and certified for hardness.


Professional installers, locksmiths and home improvers have been using our drill bits for drilling the hardest of metals.


When drilling any metal you should consult a speeds and feeds calculator.


TTP HARD drill bits are available in individual sizes or as drill sets.


Drill bit sizes

We at TTP HARD drills specialise in both imperial and metric sized cobalt drill bits.

Imperial sizes

1/16 5/64 3/32 7/64
1/8 9/64 5/32 11/64
3/16 13/64 7/32 15/64
1/4 17/64 9/32 19/64
5/16 21/64 11/32 23/64
3/8 25/64 13/32 27/64
7/16 29/64 15/32 31/64


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