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Best drill bits for stainless steel

Updated: October 2026

You have a hole to put in 304 or 316, and the amazon.co.uk page is sorted by stars. On the shelf captured on 15 October 2026, the largest review count is a plain HSS set and the highest price is an HSS-G set. Neither names the grade. The best drill bits for stainless steel here name M35 or HSS-Co and print the diameter on the drawing. The full table sits on the [stainless steel drill bit comparison](/hub/drilling-and-accessories/stainless-steel-drill-bit). Products Compared read the ten UK listings, with no lab test. A qualifying purchase can earn a commission at no extra cost to you.

You have a hole to put in 304 or 316, and the amazon.co.uk page is sorted by stars. On the shelf captured on 15 October 2026, the largest review count is a plain HSS set and the highest price is an HSS-G set.

Our top picks

Bosch Bosch PRO HSS-Co set, 19 pieces, 1–10 mm

Best overall

Bosch Bosch PRO HSS-Co set, 19 pieces, 1–10 mm
8.4/10about £34.52
View offer
Rennie Tool Company Rennie Tools 5-piece cobalt set, 4–10 mm

Best value

Rennie Tool Company Rennie Tools 5-piece cobalt set, 4–10 mm
8.3/10about £13.99
View offer
KASAFE KASAFE M35 step bit, 3–13 mm

Alternative

KASAFE KASAFE M35 step bit, 3–13 mm
7.3/10about £7.99
View offer
On this page
  1. 1.Sort by the hole, not by the star count
  2. 2.A full half-millimetre cobalt-style set
  3. 3.Five common sizes, or a step bit
  4. 4.What to leave on the shelf

Sort by the hole, not by the star count

Start with the metal and the diameter, then the grade, then the price. Bosch PointTeQ, B076F43HPH, is £11.95 with 4.5 from 4,044 ratings. The title says HSS for metal, and stainless is absent. One UK reviewer says it was the wrong set for the stainless they wanted. That volume is evidence for mild steel, roofing sheet and galvanised steel, and weak evidence for 316. Greywolf’s HSS-G set, B0DZWRGDQQ, is £60.79, the dearest box here. It states HSS-G, black and gold oxide, and a 135° tip. It does not say M35 or a cobalt percentage. Thürmer treats HSS-G as steel ground after hardening, and HSS-Co as cobalt in the steel. Paying £60.79 does not put you on the cobalt side of this shelf.

A full half-millimetre cobalt-style set

If the drawing uses 5.5 mm, 7 mm or 7.5 mm, the list has to print those sizes. Bosch PRO is £34.52, scored 4.6 from 5,129 ratings, one bit of each size from 1 mm to 10 mm, including 7 mm. Toolstation describes part family 2608587014 as HSS-Co to DIN 338 with a 135° tip. Amazon does not print a cobalt percentage, and the spec says “Centre Point”, not “split point”. UK reviews include a steel lintel and also two hours of small marks. Use £34.52. This is the top pick for ordinary 304 or 316 when you want the full metric run.
Bosch Bosch PRO HSS-Co set, 19 pieces, 1–10 mm

Testsieger

Bosch Bosch PRO HSS-Co set, 19 pieces, 1–10 mm
8.4/10about £34.52
View offer

Five common sizes, or a step bit

Rennie Tools is £13.99, with 4.4 from 207 ratings, in 4, 5, 6, 8 and 10 mm, M35 with a 135° split point. There is no 7 mm. UK reviews describe stainless after ordinary HSS had failed, with oil and a slow speed, and snaps on seized fasteners. One plating claim is a review, not a test in the file. This is the best value when those five holes are the job. A large twist bit can snatch in thin sheet. The only step bit here is KASAFE at £7.99, from 3 mm to 13 mm. Thickness is on the stainless sheet page.

What to leave on the shelf

Leave PointTeQ when the job is named as stainless. It remains a rational buy for mild steel. Leave the £60.79 HSS-G set when you came for cobalt. Irwin’s note, about its own bits, says a cobalt alloy remains after a gold colour is ground off, while a titanium nitride coat leaves the edge once you sharpen it. Leave Grevosea B0HC72S5ZG at £6.99 when you need a scored metric set. The range is 1/16 inch to 1/4 inch, the finish field says titanium, and there is no Customer Reviews line. Leave Greywolf B0DZNQZK1V (£35.90) and B0DZNTPX51 (£34.99) if you need 7.0 mm. Both titles talk about 0.5 mm steps, and both lists omit 7.0 mm. If the bit polishes and no chip forms, 304 and 316 harden whether the box says cobalt or HSS.

Common questions

Which set should you buy for ordinary 304 or 316?
For diameters from 1 mm to 10 mm, including 7 mm, Bosch PRO at £34.52 is the top pick. The listing states no cobalt percentage, and UK reviews include both clean stainless holes and jobs that barely marked. If the holes are only 4, 5, 6, 8 and 10 mm, Rennie at £13.99 covers that list. Keep a chip forming. A rubbing bit work-hardens 304 and 316.
Is the dearest set the cobalt set?
No. The dearest set on this capture is Greywolf’s HSS-G box at £60.79. It does not say M35 or HSS-Co. Bosch PRO is £34.52. Sort by the grade line, then by whether 7 mm is printed.
When is a five-piece set enough?
The Rennie case is enough when the holes are 4, 5, 6, 8 or 10 mm and you already own smaller pilots. It is the wrong box if the drawing shows 3.3 mm, 5.5 mm or 7 mm. A 13-piece Greywolf set on this shelf includes 3.3 mm and 4.2 mm and stops at 6.5 mm, so a higher piece count can still miss the diameter you need.
Do you need M42, and is it on this shelf?
Shop guides describe M42 as about 8% cobalt, for harder production work, and more brittle than M35. None of these ten listings is sold as M42. For ordinary 304 and 316, an M35 or HSS-Co listing is the cobalt-style grade this shelf offers. The cobalt versus HSS page holds that fork.
What should you skip if the bits are imperial or have no reviews?
Skip Grevosea’s £6.99 set when the drawing is metric. The range is 1/16 inch to 1/4 inch, individual millimetre sizes are not listed, and the file has no star line. The finish field says titanium, which is a different statement from M35 in the steel. An unscored listing can still be sharp. You have no UK review text to weigh before you pay.

Related pages

Cobalt drill bit set for stainless steel

Stainless steel drill bits

Cobalt vs HSS drill bits: which side of this shelf

How to drill stainless steel: speeds, feed and oil

Drill bit for stainless steel sheet, step or twist

Sources

Public UK sources and the amazon.co.uk listings captured on 15 October 2026. The 8–12 m/min cutting-speed band is a rule of thumb, not a British standard.

  1. British Stainless Steel Association — Speeds and feeds for drilling and reaming stainless steels (retrieved 15 October 2026)
  2. Health and Safety Executive — PUWER overview (retrieved 15 October 2026)
  3. Health and Safety Executive — Using the right type of PPE (retrieved 15 October 2026)
  4. legislation.gov.uk — Consumer Rights Act 2015 (retrieved 15 October 2026)
  5. Armeg — Twister impact-rated HSS cobalt drill bits (retrieved 15 October 2026)
  6. Dormer Pramet A777 — jobber drill data sheet (BS 328, DIN 338, ISO 235) (retrieved 15 October 2026)
  7. David Harries — cobalt drill technical sheet (retrieved 15 October 2026)
  8. Thürmer Tools — drill FAQ (8–12 m/min is a rule of thumb, not a British standard) (retrieved 15 October 2026)