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Countersink drill bit for wood: size the pilot, then test the edge

Updated: 2026-10-23

A countersink drill bit for wood fails in two ordinary ways. The edge of a narrow rail splits because the pilot was a label on the packet rather than a hole matched to that screw, or the head sits proud because the cone never reached a seat. Plywood and MDF add a third: the HSS edge dulls, and the exit face tears. This page stays with timber and board. The twelve listings are in the [countersink drill bit comparison](/hub/drilling-and-accessories/countersink-drill-bit). Products Compared read those amazon.co.uk pages on 19 October 2026, plus Screwfix's screw guide and the MDF note below. We did not run a lab test. A qualifying purchase can earn a commission at no extra cost to you.

A countersink drill bit for wood fails in two ordinary ways.

Our top picks

DECKRKAT DECKRKAT 8-piece countersink set

Best overall

DECKRKAT DECKRKAT 8-piece countersink set
7.7/10about £18.98
View offer
Makita Makita D-73455 4-piece countersink set

Best value

Makita Makita D-73455 4-piece countersink set
7.5/10about £7.92
View offer
EZARC EZARC 12-piece countersink set

Rank 3

EZARC EZARC 12-piece countersink set
9.0/10about £17.99
View offer
On this page
  1. 1.Three holes, not one
  2. 2.Gauge versus the bit in the box
  3. 3.Softwood, hardwood and board
  4. 4.Which of these sets are wood tools

Three holes, not one

A woodscrew that pulls two pieces together needs three diameters. The pilot is a hole the core can bite without wedging the fibres apart. The clearance hole is wide enough that the thread does not catch. The countersink is the cone under the head. Without a pilot and a place for the head, the screw splits the stile as it goes home. Screwfix's screws guide is the table quoted here. A gauge 8 is about 4 mm, with a 2.5 mm pilot and a 5 mm clearance hole. A gauge 10 is about 5 mm, with a 3.5 mm pilot and a 5.75 mm clearance hole. One other UK chart uses 2.0 mm for a gauge 8 softwood pilot, against Screwfix's 2.5 mm. Use the screw in the box when the charts disagree. If the head then bears only on a bright rim, read the 82 or 90 degree countersink page. The angle is a different fault from the gauge.

Gauge versus the bit in the box

The # marks on these Amazon sets are a seller's map, not the Screwfix column. EZARC's tapered bits are labelled #4 at 2 mm, #8 at 2.8 mm, #10 at 3.2 mm and #12 at 3.6 mm. DECKRKAT's pilots run from 2 mm to 4 mm and the listing claims #4 through #14. Screwfix's gauge 10 pilot is 3.5 mm, next to a bit sold as #10 at 3.2 mm. They are not the same hole. Makita's bullets label No.12 as 6 mm, and a reviewer measured a hole nearer 4 mm. Measure the first hole in scrap before you commit a row.
DECKRKAT DECKRKAT 8-piece countersink set

Testsieger

DECKRKAT DECKRKAT 8-piece countersink set
7.7/10about £18.98
View offer

Softwood, hardwood and board

Softwood forgives a slightly tight pilot. DECKRKAT reviews include bits that grabbed in freshly sawn timber and behaved on finished MDF and plywood. Slow the drill. The stop and the scrap screw are on the how to use a countersink drill bit page. The EZARC 22-piece, TOLESA and the EZARC 12-piece say avoid long or frequent hardwood use. HSS will start an oak hole. It is not sold here as the bit for a day of it. None of these twelve is TCT. A Makita review describes bluntness after about 30 holes in chipboard, and an EZARC 12-piece review after about 40. Support the exit face of plywood with a clamped scrap.

Which of these sets are wood tools

The hex combined sets are the wood tools: a pilot, a cone and a stop. Makita is the four-piece for short wood screws if you can live with an unresolved angle string. Torveen and Kaquxibix will chamfer wood and will not drill the pilot that stops a split. ATOPLEE names wood, then tells you not to use a hand drill. Do not take a wood set into mild steel because the cone looks similar.

Common questions

What pilot do I need for a No.8 or a 4 mm screw?
Screwfix shows a gauge 8, about 4 mm, with a 2.5 mm pilot and a 5 mm clearance hole. Another UK chart uses 2.0 mm for a gauge 8 softwood pilot. The sets here often label about 2.8 mm as #8. Those three numbers are not one answer. Drill scrap with the bit you bought, drive the screw you will use, and reject the bit if the wood splits or the screw spins.
Is the # number on an Amazon set the same as Screwfix?
No. EZARC's #10 is a 3.2 mm pilot in the listing, while Screwfix's gauge 10 pilot is 3.5 mm. EZARC's #12 is about 3.6 mm, while Screwfix's gauge 12 clearance hole is 6.5 mm and its pilot is 3.5 mm. Makita's No.12 label of 6 mm did not match a reviewer's measured hole of about 4 mm. Treat the # mark as a label until you measure.
How do I stop plywood tearing on the exit?
Clamp a piece of scrap against the exit face so the pilot cuts into support instead of bursting the veneer. A slow feed and a sharp pilot matter more than a larger countersink on the entry side. This is workshop practice for drilling sheet material, not a test result from these twelve bits. If the exit is already torn, the countersink will not close it.
How close to the edge of MDF can I screw?
The European Panel Federation's guidance is a practical minimum: face screws generally at least 12 mm from the edge and 25 mm from a corner, edge screws at least 70 mm from a corner. Use a pilot around 85 to 95 per cent of the screw core, slightly deeper than the screw, and a small counterbore so the face does not lift. Those distances are for MDF, not a rule for a pine architrave.
Do I need a clearance hole as well as a countersink?
Yes, when the screw must pull one piece against another. Clearance in the top piece lets the thread pass. The pilot in the bottom piece lets it bite. The countersink only seats the head. A combined bit can drill the pilot and the cone. It does not automatically drill the larger clearance hole. Screwfix's gauge 8 clearance is 5 mm against a 2.5 mm pilot.

Related pages

Best countersink drill bits

Countersink drill bit

82 or 90 degree countersink: match the screw in your hand

Countersink drill bit buying guide: type and angle

How to use a countersink drill bit so the head sits flush

Sources

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

  1. HSE: PUWER overview (retrieved 19 October 2026)
  2. HSE WIS23: wood dust (retrieved 19 October 2026)
  3. HSE: cutting and sanding wood (retrieved 19 October 2026)
  4. HSE L25: eye protection (retrieved 19 October 2026)
  5. GOV.UK: General Product Safety Regulations 2005 (retrieved 19 October 2026)
  6. Consumer Rights Act 2015, section 20 (retrieved 19 October 2026)
  7. Screwfix: screws buying guide (retrieved 19 October 2026)
  8. BSI: BS EN ISO 10642:2019 (retrieved 19 October 2026)