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 M35
Cobalt M35

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
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
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.

<h4>FREE DELIVERY</h4>

FREE DELIVERY

FREE next working day delivery on all orders over £50

<h4>TRUSTED</h4>

TRUSTED

Selling drill bits for 40+ years — Established in 1985

<h4>OUR GUARANTEE</h4>

OUR GUARANTEE

100% satisfaction guaranteed or your money back

<h4>FULFILMENT</h4>

FULFILMENT

Over 1,000,000 items in stock & same-day dispatch promise

Trade Trusted Reviews

4.7/5 Over 4,900 independent company reviews company reviews Verified by REVIEWS.io

carl tiffany

★★★★★

Always Helpful and Fast Over the Counter Service at a Great Price

Verified buyer · 28 Sept 2026

david byatt

★★★★★

Very quick delivery . Good cobalt drills that did the job .

Verified buyer · 26 Sept 2026

anonymous

★★★★★

Always good prices and have what I'm looking for. Very quick delivery. Excellent. Thank you

Verified buyer · 26 Sept 2026

nigel scott

★★★★★

Good easy to use website, good price drill arrived on time.

Verified buyer · 25 Sept 2026

stewart granger

★★★★★

5 Star s great drill bits

Verified buyer · 24 Sept 2026

richard oakman

★★★★★

Excellent company to deal with I have used them several times and the delivery and pricing is really good.no complaints on any of the items I have purchased. The drill bits cut which can't be said of some other companies I have used.

Verified buyer · 24 Sept 2026