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How to use a drill bit

Updated: 2026-10-23

The bit is in the drawer and the hole is about to go wrong through heat, dust or a cable you have not looked for. How to use a drill bit is a sequence: match the bit, mark and punch metal, set the speed and the oil, then deal with dust and services. Star ratings do not keep a tip from turning blue. The sets these examples come from are in the [drill bit comparison](/hub/drilling-and-accessories/drill-bit). Products Compared used amazon.co.uk listings and HSE and Bosch DIY UK guidance on 22 October 2026, and did not run a lab test. A qualifying purchase can earn a commission at no extra cost to you.

The bit is in the drawer and the hole is about to go wrong through heat, dust or a cable you have not looked for.

Our top picks

Bosch Bosch 34-piece X-Line

Best overall

Bosch Bosch 34-piece X-Line
9.4/10about £10.63
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Bosch Bosch Mini X-Line 15-piece

Best value

Bosch Bosch Mini X-Line 15-piece
9.4/10about £7.99
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Bosch Bosch PointTeQ 19-piece HSS

Alternative

Bosch Bosch PointTeQ 19-piece HSS
8.4/10about £14.12
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On this page
  1. 1.Put the right bit in the chuck
  2. 2.Mark the hole and punch metal
  3. 3.Speed, pressure and oil
  4. 4.Dust, eyes and what is behind the wall
  5. 5.When to stop

Put the right bit in the chuck

Hammer mode stays off for HSS, for a brad-point wood bit, for a spade bit and for a step bit. It goes on only for a carbide masonry bit in brick or block. The Mini X-Line names that carbide tip. The 34-piece and 50-piece name the masonry bits as CYL-1. PointTeQ stays on rotary. Cobalt belongs in the chuck only when the listing says M42, still slow and with oil, which is the HSS or cobalt drill bits page. None of these listings is SDS. Seat the shank fully and tighten all three jaws, or click a hex shank home until it locks.

Mark the hole and punch metal

Mark the centre, then check the far side of a wall before you commit. On metal, one firm tap with a centre punch leaves a dimple so the HSS tip does not skate. The LSLANSOON case includes an S2 punch. Any punch you own does the same job. A brad-point wood bit needs the mark and does not need the punch. A masonry bit wants a light rotary start, then hammer mode. Plug diameter comes from the pack, on the masonry drill bit page. Bosch DIY's depth rule of thumb for an anchor is the anchor length plus 10 mm. Clean the dust out before the plug goes in.
Bosch Bosch 34-piece X-Line

Testsieger

Bosch Bosch 34-piece X-Line
9.4/10about £10.63
View offer

Speed, pressure and oil

Bosch DIY UK: a higher speed for a small bit in soft material, a lower speed for a large bit in hard material. Use cutting fluid on metal, or withdraw the bit, before the tip turns blue. If the swarf is powder, you are rubbing. UK Drills' chart, as their starting point and not a measurement of these bits, suggests about 1,500 rpm for a 6 mm HSS bit in mild steel and about 650 rpm in stainless, slower as the bit gets larger. WD-40 flashes off and is a poor coolant on steel. Stainless work-hardens if the bit rubs. Back the bit out so the flutes clear.

Dust, eyes and what is behind the wall

Brick, block, mortar and concrete dust can contain respirable crystalline silica. On a short hole, about 15–30 minutes in a day, HSE CN3 says capture the dust. When drilling is the main work of the day, the same guidance wants on-tool extraction in M or H class. When you are not extracting, respiratory protection with an assigned protection factor of at least 20 applies, and tight-fitting masks need a fit test. A water quench on a hot masonry tip can crack the carbide braze. Before a wall, look on both sides for cables and for anything that might be asbestos. A detector can miss a low-current wire. If the cable route is unknown, CIS65 says turn the power off. Gas is the same stop.

When to stop

Stop when the tip colours, when you cannot say where the cables or the gas pipe run, or if you suspect asbestos. Stop if the fixing is a rated anchor or a boiler flue. A day of concrete without extraction and a face-fit mask is a professional job. A plastic plug in brick, at the pack size, with a carbide bit and the power confirmed off, is the household job these straight-shank sets are for.

Common questions

Should hammer mode be on?
Turn hammer mode on for a carbide masonry bit in brick or block, after the tip has seated. Leave it off for HSS in metal, for brad-point and spade bits in wood, and for a step bit in sheet. These listings are straight-shank bits for a combi drill. They are not SDS bits.
Do I need cutting oil on metal?
Yes for steel, and especially for stainless. Bosch DIY says use cutting fluid or back the bit out before the tip turns blue. WD-40 is a poor coolant on steel because it flashes off. Aluminium can often be drilled dry at a sensible speed, and it still wants you to clear the flutes.
Why centre-punch metal?
An HSS twist bit walks on a smooth face if the tip has nowhere to sit. A centre punch leaves a small dimple so the cutting lips start in one place. The LSLANSOON set includes an S2 punch as an example of that tool in a case. You punch, then drill.
What mask do I need for brick dust?
For a short hole, capture the dust if you can, and wear eye protection. If you are not extracting, HSE CN3 points to respiratory protection with an assigned protection factor of at least 20. Drilling masonry as the main job of the day wants on-tool M or H class extraction. Tight-fitting masks need a fit test.
How do I check for cables before I drill a wall?
Look at both sides of the wall, and use a detector with the limit that it can miss a low-current cable. If you still cannot say where the cables run, CIS65 says turn the electricity off before you drill. Do the same if you are unsure about gas. A suspected asbestos board is a stop, not a careful hole.

Related pages

Best drill bits

Drill bit buying guide

Drill bit

Masonry drill bit for brick plugs, hammer and dust

HSS or cobalt drill bits for mild steel or stainless

Sources

Public UK sources from the research digest. Shelf prices and star lines are the amazon.co.uk figures in the display file.

  1. HSE CN3: silica dust and APF 20 (retrieved 22 October 2026)
  2. HSE CIS36: drilling and respirable crystalline silica (retrieved 22 October 2026)
  3. HSE: electricity, drilling near cables (retrieved 22 October 2026)
  4. HSE CIS65: power off if cable routes are unknown (retrieved 22 October 2026)
  5. Bosch DIY UK: guide to drills (retrieved 22 October 2026)
  6. Screwfix: guide to types of drill bits (retrieved 22 October 2026)
  7. Rawlplug UNO universal plug (retrieved 22 October 2026)
  8. CMT: standard plastic wall plugs (retrieved 22 October 2026)