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Step drill for sheet metal

Updated: 2026-10-23

The packet says for metal, and the sheet might be 1 mm aluminium, 2 mm mild steel, or a stainless bracket another listing has already banned. A step drill for sheet metal is honest only inside the thickness sentence printed for that bit. The twelve amazon.co.uk listings in our [step drill comparison](/hub/drilling-and-accessories/step-drill) do not share one cap. Those caps were lined up on 22 October 2026 from the saved listings, not from a lab cut. A review that went through 10 mm stays an anecdote. The working sequence is on [how to use a step drill bit](/hub/drilling-and-accessories/step-drill/sub/step-drill-how-to-use). A qualifying purchase can earn a commission at no extra cost to you.

The packet says for metal, and the sheet might be 1 mm aluminium, 2 mm mild steel, or a stainless bracket another listing has already banned.

Our top picks

YOKOCUT YOKOCUT M35 4–32 mm, 15 steps

Best overall

YOKOCUT YOKOCUT M35 4–32 mm, 15 steps
8.0/10about £27.50
View offer
YOKOCUT YOKOCUT 4–22 mm HSS 4241

Best value

YOKOCUT YOKOCUT 4–22 mm HSS 4241
8.6/10about £5.12
View offer
ss shovan ss shovan 3-piece, 2-flute

Rank 3

ss shovan ss shovan 3-piece, 2-flute
8.8/10about £11.99
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On this page
  1. 1.The thickness lines do not match
  2. 2.Mild steel and aluminium
  3. 3.Stainless is a different listing
  4. 4.When the cone is the wrong cutter

The thickness lines do not match

Read the cap on the bit, and refuse a blended number. DeWalt’s bullets and Ultimate Handyman talk about thin sheet up to about 3 mm. Several YOKOCUT HSS 4241 pages allow within 4 mm on iron, copper and aluminium. The 4–42 mm YOKOCUT says within 3 mm. The ss shovan two-flute set says not thicker than 8 mm. QWORK says stainless under 1 mm. DURI names stainless and prints no millimetre cap. That gap is not permission. If the cone says 3 mm and the panel is 4 mm, you are outside the listing. Clamp the sheet and back it, because thin sheet grabs at breakthrough. Plastic boxes in the same reviews are not a thickness rating for steel.

Mild steel and aluminium

Mild steel and aluminium are what these HSS cones are described for, inside the cap. Reviews of the two-flute ss shovan set mention 2 mm steel, thin boxes, a wheel arch and a camper. The about £5.12 YOKOCUT has one report of 3 mm steel opened from 6 mm to 15 mm, and other buyers who found the edge too soft. A dry cone blues on 1 mm plate. DURI reviews include three bits burnt out on 1 mm plate and tips snapped in 5 mm mild steel, at 4.0 from 26 reviews and with no cap. Where the listing says within 4 mm, a 10 mm claim is not a new rating. Bodywork here means a thin panel, not a chassis rail.
YOKOCUT YOKOCUT M35 4–32 mm, 15 steps

Testsieger

YOKOCUT YOKOCUT M35 4–32 mm, 15 steps
8.0/10about £27.50
View offer

Stainless is a different listing

HSS 4241 and HSS M2 pages that print an exclusion are not for stainless. One review of the 4–42 mm bit says it would not cut 1.5 mm stainless. The only row that states stainless under 1 mm is QWORK, with no Customer Reviews line, inch sizes and a price of about £20.99. The YOKOCUT M35 cone at about £27.50 is 4.6 from 309 reviews, 4–32 mm, on a 10 mm tri-flat. One review describes eight 30 mm holes in 4 mm galvanised plate with fluid and a pilot. Others describe a bit finished after one hole in 2 mm stainless. The title says 6% cobalt and the bullet says 5%. Rarapop names stainless, has 21 reviews and prints no cap. Past that sentence, use a hole saw or a punch, on step drill vs hole saw.

When the cone is the wrong cutter

Past the printed cap, more pressure makes a blunt cone and an oval hole. A bench drill does not invent a new cap. The 42 mm cone is described as the limit of a cordless drill, and its metal cap is 3 mm. Glass, tile and walls sit next to stainless on the YOKOCUT exclusions. Most cones here stop at 32 mm. QWORK stops at 7/8 in. A cone often leaves a lighter burr than one large twist drill, not a burr-free edge. Deburr after the drill has stopped. If the box must stay free of swarf, look at a punch. Shank and grade are on the step drill bit buying guide.

Common questions

How thick a sheet can a step drill cut?
Whichever cap is printed on the bit you bought. In this set that might be about 3 mm on DeWalt’s bullets, within 4 mm of iron on several 4241 pages, within 3 mm on the 4–42 mm cone, not thicker than 8 mm on the ss shovan two-flute set, or under 1 mm of stainless on QWORK. Do not average those into one UK figure. A missing cap, as on DURI, is a gap.
Is it suitable for stainless?
Only on a listing that says so, and only inside that listing’s limit. HSS 4241 and M2 rows here that say not suitable are a no. QWORK says under 1 mm and has no reviews on this capture. The about £27.50 M35 cone has mixed UK reviews, including both a run of holes in galvanised plate and bits that failed quickly in stainless. Cobalt on the label is not a measured life.
Will it work on aluminium bodywork?
Thin aluminium sheet is one of the kinder cuts in the reviews, including cladding and light panels, as long as you clamp it and stay inside the cap. Bodywork in the Ultimate Handyman sense is that thin sheet, not a structural member. The sheet can still grab at breakthrough. A gold coat is not what makes the hole round.
Why did it burn on 1 mm plate?
Heat, speed and a soft edge, not a mysterious fault in thin metal. DURI reviewers report all three cones burnt out on 1 mm plate, and a dry or fast cut will blue any of these HSS bits. Use cutting fluid, drop the speed, and ease off as the step breaks through. If the listing gave no thickness and named stainless anyway, the burn is also a clue that the page never set a limit.
Is a review of 5 mm or 10 mm steel a rating?
No. Where the listing says within 3 mm or 4 mm, a review of thicker plate is an anecdote. The DeWalt bullets stop at 3 mm even if someone reports 5 mm holes in steel. The M2 page stops at 4 mm of iron even if someone claims 10 mm. Use the sentence on the product page you are buying.

Related pages

Best step drill bit UK

Step drill

Step drill bit buying guide: hole, steel and shank

How to use a step drill bit on thin sheet and plastic

Step drill vs hole saw for thin sheet, plate or a box

Sources

Public UK sources from the research digest, last checked on 22 October 2026. Shelf prices and star lines are the amazon.co.uk figures in the saved listings for this comparison.

  1. HSE, PUWER overview (retrieved 22 October 2026)
  2. HSE, PPE types (retrieved 22 October 2026)
  3. HSE CN3, silica and concrete drilling (retrieved 22 October 2026)
  4. Consumer Rights Act 2015, section 9 (retrieved 22 October 2026)
  5. GOV.UK, General Product Safety Regulations 2005 (retrieved 22 October 2026)
  6. BSI, BS 328-1 twist drills (retrieved 22 October 2026)
  7. DeWalt UK, DT5026-QZ (retrieved 22 October 2026)
  8. Ultimate Handyman, drilling metal (retrieved 22 October 2026)