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Black Oxide Drill Bits – 12 – 13mm

From: $26.75


  • Black Oxide for greater lubricity & sharpness protection
  • 1 Pack contains 5 drill bits
  • US sourced metal, milled in the EU
  • fully ground drill bits, hardened and strengthened
  • Premium quality drill bits used in the metal fabrication industry
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Product Description



These HSS drill bits are coated in black oxide specifically for hardened steel are perfect for general purpose use. We distribute these to  Do-It-Yourself (DIY) and professional tradesmen alike.  These are treated to 950 degrees Fahrenheit in order to create a black oxide finish.  This makes them able to provide mild rust and corrosion resistance properties.

Black oxide drill bits generally last up to 50% longer than untreated HSS drill bits. The added benefit to the black oxide treatment process is lubricity which enables the drill to penetrate the hardened material quicker.

It’s hard to go past these HSS drill bit tools when you’re looking for good quality hardened steel products.  The point angle of 135 degrees is the most suited for drilling into hardened materials such as stainless steel with portable drills. Drill bits with a 118-degree point angle are better suited to softer materials such as wood. Cobalt drill bits are superior and more expensive than the high-speed steel alternatives. Cobalt will drill through-hardened steel due to its high-temperature manufacture. There is a trade-off to this process as it makes the drill bit more brittle than a high-speed steel one. Our black oxide coated hss drill bits are a good balance between the most expensive cobalt tools and the untreated non-coated drill bits.


Zip Tie Guy offers a range of black oxide drill bit products in metric or imperial sets, single bits or in quantities of single measurement packs. Currently, we offer 5, 10 or 20 bit packs that our customers depending on their requirements can purchase individually or complement their existing drill bit sets.

Fully Ground v Half Ground

You will often see the term half and full ground drill bits. Half ground drill bits go through a process that involves roll forging then grinding down to the flutes. A fully ground drill bit is just that, ground along its entire length. The latter method aids a more precise drill action where tolerances are crucial. General-purpose drill bits advertised as half ground are generally less expensive however suitable for general use.

At Zip Tie Guy we’ve sourced a  manufacturer who produces good quality drill bits. Check out our range and purchase a set, you won’t be underwhelmed.

Shipping Faq


12mm, 12.5mm, 13mm


1 Pack of 5, 1 Pack of 10, 1 Pack of 20