Drilling Hardened Steel

Not sure how hard the steel is? Start with cobalt. If that fails, step up to TCT — and if in doubt, ask us.

Cobalt is the first step when drilling hardened or unknown steels.

M35 (5% cobalt) holds its edge under heat, so it suits tougher steels, stainless and repeated drilling where standard HSS blunts.

Run at low speed with steady pressure and cutting fluid. Harder, heat-treated or work-hardened material? Step up to M42.

Cobalt M42

M42 (8% cobalt) offers higher heat resistance and edge retention than M35.

For harder, heat-treated or work-hardened steel and high-alloy stainless – the top of our metal drilling range, with a 135° split point for a clean start.

Low speed, steady pressure, cutting fluid. If cobalt fails to cut, step up to TCT.

TCT

Tungsten carbide-tipped drill bits for when cobalt isn’t enough.

Designed for extreme materials such as hardened bolts, high-tensile fasteners, security plates, and work-hardened steel. Commonly used by locksmiths, fabricators, and engineers.

Requires precise setup, low speed, and controlled pressure. Not suitable for general steel drilling.