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Automatic centre punch for mild steel and stainless

Updated: 22 October 2026

The drill walks off a pencil cross on mild steel, and the punch in the drawer was bought for flat-pack fittings. An automatic centre punch for metal has to leave a dimple deep enough for that bit, in that stock, without dishing thin aluminium or treating a hardness word as a test. Wood and glass are not this page. If the spring's maximum is still a pinprick, the next choice is a solid punch and a hammer, on the [automatic centre punch vs hammer](/hub/hand-tools/automatic-centre-punch/sub/automatic-centre-punch-vs-hammer) page. The twelve listings are the [automatic centre punch comparison](/hub/hand-tools/automatic-centre-punch). A qualifying purchase can earn us a commission at no extra cost to you. Peter F. wrote this on 21 October 2026 from amazon.co.uk review notes, not from a lab test.

The drill walks off a pencil cross on mild steel, and the punch in the drawer was bought for flat-pack fittings.

Our top picks

Starrett Starrett 18A

Best overall

Starrett Starrett 18A
7.6/10about £32.00
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Starrett Starrett 18C

Alternative

Starrett Starrett 18C
7.0/10about £26.46
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Eclipse Eclipse 65-171R

Best value

Eclipse Eclipse 65-171R
7.0/10about £9.00
View offer
On this page
  1. 1.Mild steel
  2. 2.Stainless and thicker sheet
  3. 3.Aluminium and thin sheet
  4. 4.What the listing metal words do not prove

Mild steel

Mild steel is where a light automatic shows its limit. Many of the 42 UK texts on the Starrett 18AA, titled at 4 in, say it does not leave a useful dot on mild steel, while the same file is comfortable on aluminium, wood and trunking. The Eclipse 65-171R, 4.3 from 1,381 ratings at £9.00, is often called too shallow on mild steel even at maximum, including repeats on 1.4 mm sheet. The listing says not to use a hammer. The 18A, 4.7 from 3,736 ratings at £32.00, is cited for spot-weld drilling and still called a little light. QWORK texts at £4.99 find a usable mark they do not call deep. The S&R at 60–130 N is cited for 2.5 mm box section if you press firmly. Do not rewrite Starrett's pound ladder as those newtons.

Stainless and thicker sheet

When the texts want a heavier dent, they name the Starrett 18C: 4.4 from 2,296 ratings at £26.46, titled at 5-1/4 in, listed at 132 g. Reviewers describe a heavy indentation in stainless and in 4 mm sheet. That is not a certificate for every stainless grade. Several say the spring is hard to trigger, sometimes with both hands. A heavy class you cannot fire does not mark. Punches have failed to trigger out of the box, and a spare point is not in the included line. If the dimple is still too small, change method. Striking the 18C is not the thicker-sheet technique.
Starrett Starrett 18A

Testsieger

Starrett Starrett 18A
7.6/10about £32.00
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Aluminium and thin sheet

Thin aluminium punishes a setting learned on steel. One S&R review says unsupported soft metal dishes instead of taking a pinpoint. Support the work and start at the light end. The 18AA is already used on aluminium car bodies and is too gentle for mild steel. A maximum 18C press on thin aluminium makes a crater. The 4 mm figure belongs to 18C reviews, not to a cheap pack whose bullet lists thin steel. Clamp sheet that will flex.

What the listing metal words do not prove

HSS, S2, CR-V, chrome and hardened are listing words, not a hardness test and not a strike class. The Oavie HSS claim has no stainless trial in seven texts. The SabreCut S2 tip snapped, including after about 30 strikes at maximum. The Vylro's 5.0 has no review text. Stainless steel on the 18A material field clashes with all-steel bullets and describes the tool, not the workpiece. A window-breaker bullet names no glass type. Buy the strike class the reviews describe on the stock you have.

Common questions

Will an automatic centre punch mark mild steel?
Sometimes, and often not deeply enough for a drill. Many 18AA texts say the dot is not useful on mild steel. Eclipse texts often call the mark too shallow even at maximum, including repeats on 1.4 mm sheet. The 18A is used for metalwork and still called a little light. A QWORK may leave a usable mark that reviewers do not call deep. Match the class to the hole, rather than to the word steel in the title.
Is the Starrett 18C the one reviews cite for stainless and thicker sheet?
Yes, in this set. The 18C texts name stainless and 4 mm steel sheet, from 4.4 across 2,296 ratings. They also describe a stiff press, a narrow cap, and punches that failed to trigger. It is the heavy spring reviewers point at, not a guarantee for every stainless grade, and not a hammer.
What happens on thin aluminium if the setting is high?
The sheet dishes. One S&R review says unsupported soft metal dimples instead of taking a pinpoint, and 18C texts call that punch too powerful for light work. Support the panel and start at the light end. The 18AA is the class already used on aluminium car bodies, with the opposite limit on mild steel.
Is a chrome or HSS tip proof it will mark stainless?
No. HSS, S2, CR-V, chrome and hardened are listing words, not a hardness test and not a strike class. The Oavie HSS claim is not backed by a stainless review in the seven texts. The SabreCut's S2 tip still snapped in the problem list. The 18A's stainless steel material field conflicts with all-steel bullets and describes the tool, not the workpiece.
Can a £4 two-pack replace a heavy punch on steel?
Not on the evidence in these files. The QWORK at £4.99 has 329 ratings and texts that call the steel mark short of deep, with missed trips. The LeeQunQ at £3.79 has two texts, one of them not heavy-duty and one a jam after three marks. Use a cheap pack for a light mark you can afford to miss. Use the 18C class, or a hammer, when the dimple must hold a drill in harder stock.
What should you do when the dimple is only a pinprick?
Stop repeating a setting the reviews already call too shallow. Step up a class, from an 18AA or an Eclipse towards an 18A or an 18C, or change to a solid punch and a hammer if you are already at the heavy spring's maximum. Do not hit the automatic, and do not treat a new steel adjective on the same punch as a deeper blow.

Related pages

Best automatic centre punch

Automatic centre punch buying guide

Automatic centre punch

How to use an automatic centre punch, step by step

Automatic centre punch vs hammer and a solid punch

Sources

Public UK and maker sources from the research digest, last checked on 22 October 2026. Shelf prices and star lines are the amazon.co.uk figures captured on 19 October 2026.

  1. Starrett, punches: types and uses (retrieved 22 October 2026)
  2. Starrett UK, 18A automatic centre punch (retrieved 22 October 2026)
  3. Starrett 18-series data sheet (retrieved 22 October 2026)
  4. Spear & Jackson, Eclipse automatic centre punches (retrieved 22 October 2026)
  5. HSE, PUWER overview (retrieved 22 October 2026)
  6. HSE, using the right type of PPE (retrieved 22 October 2026)
  7. Consumer Rights Act 2015 (retrieved 22 October 2026)
  8. Resqme, tempered-glass limit on spring breakers (retrieved 22 October 2026)