How to use a countersink bit
Updated: 23 October 2026
You have a cordless drill, a box of countersunk screws, and a bit that might be a plain cone or a cone with a skinny pilot. The head should finish flush. If you push until the cutter squeals, you get a crater, a hexagonal seat, or a pilot snapped off in the timber. This is how to use a countersink bit on a Saturday job: which pass comes first, how deep to go on scrap, and when to stop. Product choice stays on the [countersink comparison](/hub/drilling-and-accessories/countersink). The Products Compared editorial team based the steps on UK how-to pages and on the review complaints in this comparison, dated 20 October 2026. We did not run a workshop test. A qualifying purchase can earn a commission at no extra cost to you. Wear eye protection. Clamp the work. At work, your employer’s PUWER arrangements apply; this page is a home method.
You have a cordless drill, a box of countersunk screws, and a bit that might be a plain cone or a cone with a skinny pilot. The head should finish flush.
You have a cordless drill, a box of countersunk screws, and a bit that might be a plain cone or a cone with a skinny pilot. The head should finish flush. If you push until the cutter squeals, you get a crater, a hexagonal seat, or a pilot snapped off in the timber. This is how to use a countersink bit on a Saturday job: which pass comes first, how deep to go on scrap, and when to stop. Product choice stays on the countersink comparison. The Products Compared editorial team based the steps on UK how-to pages and on the review complaints in this comparison, dated 20 October 2026. We did not run a workshop test. A qualifying purchase can earn a commission at no extra cost to you. Wear eye protection. Clamp the work. At work, your employer’s PUWER arrangements apply; this page is a home method.
Our top picks
| Badge | Product | How you cut | Depth stop | Typical failure | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Makita Makita D-73455 4-piece set | One combination pass | How far the pilot sticks out | Small pilots snap in thin ply | 9.0 | about £7.92 | View offer |
| Alternative |  Gasea Gasea 3-piece 90° countersink | Pilot first, then the cone | Tape on a separate drill | Crater if you keep drilling | 8.8 | about £4.99 | View offer |
 EZARC EZARC 12-piece countersink set | One combination pass | Allen key on the grub screw | Pilot slips or the screw strips | 8.6 | about £17.99 | View offer |
On this page
Pilot, then cone, or one combination pass
A flush seat is a cone that matches the underside of the head, deep enough that the head does not stand proud and shallow enough that you have not chewed a dish around it. If the bit is only a chamfer, drill the pilot first, then bring the cone in on that hole. DIY Doctor’s order is the same: pilot, a depth mark, then a light push with the countersink. ASP Ltd says the pilot should be slightly under the screw so the thread still bites, and you should test the screw in the seat before you drive it home. The cone only has to clear the head. If the bit is a combination tool, the pilot and the cone are one pass. Makita’s D-73455 and the EZARC sets are that type. You still set how far the pilot sticks out, because that length is your depth. A Makita reviewer measured about 4 mm from a bit marked 6 mm. That smaller hole is what lets a wood screw cut its thread. Keep the drill in line with the hole. A combination pilot that enters at an angle walks. Start the chuck, let the pilot find the centre, and only then bring the cone onto the face. Speed comes down as the cutter gets wider and the material gets harder. Light pressure keeps the flutes cutting. Pressure that stalls them rubs the edge blunt.
Set the depth on scrap
Proud heads are almost always a depth problem, not a brand problem. On scrap of the same thickness, cut one seat and drop the screw in without driving it. If the head stands up, you need a little more cone. If the head falls below the face, you have gone too far. There is no single millimetre that fits every screw. A No. 8 head and a 50 mm coach screw are not the same cone. A piece of tape on the drill bit, as DIY Doctor suggests, is enough when you are using a separate twist drill and a separate chamfer. On an adjustable combination bit the stop is the grub screw. EZARC reviews mention an Allen key for that screw. Tighten it until the pilot cannot be pulled out by hand. Reviews of that set include grub screws that strip, pilots that slip until the screw is fully tight, and pilots that arrive bent. If the pilot creeps while you drill, the cone suddenly digs and the seat goes deep on one side. Stop when the screw head seats. Then drive it. A seated head that you keep turning will crush the fibres and split a narrow rail even though the cone looked right. If the head still rocks in a seat that looks deep enough, the angle may not match the screw. That is the 82 or 90 degree countersink problem, not a reason to cut deeper. Gasea reviews include a short burst in reverse to clean a wood seat. Treat that as something buyers tried in timber, not as a step to copy in metal. The ATOPLEE listing forbids hand drills entirely. That single HSS cutter belongs in a pillar drill or a machining centre, not in this pistol-drill sequence.
If the seat is rough or the pilot slips
A hexagonal or flower-shaped seat is chatter. The cutter is bouncing instead of slicing, so each flute stamps a flat. Woodworking Stack Exchange threads describe the same mark from speed, pressure and a drill that is not held steady, and a five-flute bit can wander into a polygon. A YXIING review in this comparison describes a lumpy, flower-shaped seat in an aluminium router plate. The fix on scrap is slower speed, less push, and both hands keeping the chuck on the axis. Clearing chips matters. LIBRATON reviewers got 18 mm plywood to behave with light pressure when they cleared the drill. Packed flutes rub, and a rubbed edge chatters more on the next hole. Gasea reviews say softwood and kiln-dried timber can look untidy unless the speed is high. That fights the “always go slowly” rule, so test one hole. A wide carbon-steel chamfer in soft pine can burnish if it turns too slowly, and the same bit in oak can grab if it turns too fast. You are looking for a continuous curl or a clean powder, not dust that smells of burning and a shiny ring. A pilot that slips is usually the grub screw or a flat in the wrong place. EZARC reviews include pilots that come loose until the screw is fully tightened. If the flat does not meet the screw, retire that pilot. Do not keep drilling while it walks, because the cone will cut an oval and the screw will sit crooked.
When to put the drill down
Clamp anything that can spin. A small offcut on a bench, held by your fingers, is how a chamfer bit catches and the wrist goes with it. Eye protection stays on, including for the chips from a carbon-steel cone. If the piece is structural, or the screw is in a joist hanger, or you are not sure the pilot is in sound timber, that is no longer a furniture trick. Stop and get someone who specifies fixings for that job. A snapped pilot is a small drill broken in the hole, not a cue to attack it with a bigger bit. Makita reviews include a tip that snapped on the second hole in 4 mm ply. EZARC and LIBRATON reviews include fine pilots that snap, including when the bit is hot. Back the combination body out. If a stub is proud, you may grip it. If it is buried in a cabinet door, drilling it out with a blunt stub still in the hole usually wrecks the face. Plug the damage and move the screw, or take the door to someone with a drill press and a left-hand bit. This page does not give a procedure for drilling hardened stubs out of a finished face. Plug cutters are the other time to put the pistol drill down. LIBRATON’s listing says they are best on a bench drill. If your listing is ATOPLEE, you should not have started in a hand drill at all. When the seats start to look dull or hexagonal again, the edge is tired. A Gasea review talked about wear after about half a dozen holes, and an EZARC review about chipboard after about 40. Those are anecdotes, not a life in minutes. Change the bit when the scrap test fails.
Common questions
Do I drill the pilot or the cone first?
Drill the pilot first when the countersink is only a chamfer, then cut the cone on that hole. Use one pass when the bit is a combination tool with its own pilot, and set the pilot length before you touch the workpiece. Either way, try the screw in scrap before you commit to the door or the rail. The cone does not need to be wider than the head.
How do I stop the head sitting proud?
Cut a fraction more cone and test again. Tape on a separate drill, or the grub screw on a combination bit, is your depth stop. If the head is proud, you stopped early. If it sinks into a dish, you went too far. Driving the screw harder will not finish a cone that is too shallow, and it can split the wood once the head is already seated.
Why is the seat hexagonal?
The cutter is chattering. Speed, pressure and a drill that wobbles off the axis leave a flat for each flute. Slow down, ease off, and hold the chuck in line. Clear the chips. The same flower shape shows up in a YXIING review of an aluminium plate. A fresh test on scrap tells you whether the bit is blunt or the hands were the problem.
How tight should the grub screw be?
Tight enough that you cannot pull the pilot out by hand, and tight enough that it does not creep after the first hole. EZARC reviews describe pilots that stay put only when the screw is fully tightened, and screws that strip. Use the Allen key in the box. If the thread is already rounded, that body will not hold a depth and should come out of the drill.
What speed should I use?
Slower as the countersink gets larger and the material gets harder, with light pressure so the edge cuts. Softwood with a small carbon-steel chamfer can look untidy if you go too slowly, which is what some Gasea reviews describe, so one scrap hole is the check. Burning, a shiny ring, or a hexagonal seat means you change speed or pressure before the next screw.
The pilot snapped in the wood. What now?
Stop. Do not lean on the broken stub with the countersink body still in the chuck. If the stub is proud you may be able to grip it. If it is below the surface of a finished piece, drilling around it usually scars the face. Move the screw or plug the hole. Combination pilots in the Makita, EZARC and LIBRATON reviews do snap, especially the fine sizes and especially once the bit is hot.
When should I move the job to a pillar drill?
When the listing says hand drills are not allowed, as ATOPLEE does, and when you are cutting plugs, as LIBRATON recommends a bench drill for its plug cutters. Also when the workpiece is small, hard, or already finished and a wandering pistol drill would wreck it. A cabinet door you can clamp on the bench is still a hand-drill job if the bit is a hex-shank combination countersink and the scrap test looks clean.
Related pages
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 display file.
- HSE PUWER overview (retrieved 22 October 2026)
- HSE L114, Safe use of woodworking machinery (retrieved 22 October 2026)
- HSE WIS23, Wood dust (retrieved 22 October 2026)
- HSE EH44, Dust and eye protection (retrieved 22 October 2026)
- Consumer Rights Act 2015, section 22 (retrieved 22 October 2026)
- Fastenerdata: screw heads (retrieved 22 October 2026)
- ISO 10642:2026 (retrieved 22 October 2026)
- BSI: BS EN ISO 10642:2019 (retrieved 22 October 2026)