Drill Bits — Interactive Guide

THREAD	TAP DRILL Ø	THREAD	TAP DRILL Ø
M2	1.6 mm	M6	5.0 mm
M2.5	2.0 mm	M8	6.8 mm
M3	2.5 mm	M10	8.5 mm
M3.5	2.9 mm	M12	10.2 mm
M4	3.3 mm	M16	14.0 mm
M5	4.2 mm

🚑 TROUBLESHOOTING — common problems & fixes

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PROBLEM	CAUSE	FIX
Bit wanders off the mark	Point skidding on smooth/hard surface	Centre punch (metal) or awl mark (wood); use a brad point bit
Hole burns / wood blackens	Speed too high or dull bit	Slow down, use a sharp bit, pull out to clear chips
Bit slips in the chuck	Loose chuck or smooth shank	Tighten a keyed chuck fully (all three holes); wipe oily shanks
Bit breaks	Side force, forcing, or too-small pilot	Keep drill square, feed gently, use a centre drill for starts
Ragged exit hole / tear-out	Spindle (twist) bit bursting through	Back the work with scrap wood; use a brad point
Bit won't start on metal	Point skids on smooth steel	Centre punch first — it gives the point a socket to bite
Chips clog / bit jams	Swarf not clearing the flutes	Withdraw often, add cutting fluid, use a higher-helix bit
Screw head won't sit flush	Wrong countersink angle	Use 82° for standard countersunk screws, 90° for metric
Blue shavings / burning smell (metal)	Too fast, no lubricant	Slow down and use cutting fluid — blue = ruined temper
Oversized / not-round hole	Worn chuck or spindle run-out; tilted feed	Use a drill press; check chuck jaws; feed square
Bit stuck in the hole	Binding on deep cut	Reverse slowly, clear chips, never force it

📋 HOW TO DRILL A HOLE — step by step

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Mark the spot. Pencil cross on wood, then centre-punch it on metal so the bit can't skid.
Choose the bit. Right type for the material, right size, and check it's sharp.
Clamp the work. A bit can snatch and spin the whole piece — always secure it.
Pilot first. For anything over ~6 mm, drill a small pilot hole first.
Start slow and square. Bring the bit to the mark at low speed, then straighten up.
Feed steadily. Let the bit cut; withdraw to clear chips; use fluid on metal.
Ease off at breakthrough. The last few millimetres grab — lighten pressure.
Finish. Deburr the hole, blow out chips, wipe the work.

⚒ SHARPENING & CARE

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Twist drills

Sharpen on a bench grinder to a 118° point — keep both cutting edges the same length and angle.
Dip in water often — overheating turns the steel blue and ruins the temper.
A sharpening jig keeps the angles identical; freehand takes practice.

Spade & brad point bits

Spade: file the flat cutting corners flat and square — never the centre point.
Brad point: lightly stone the inside of the spurs only.

Carbide & diamond tips

Masonry, tile and diamond bits are NOT hand-sharpened — replace the tip or the bit.
Keep diamond rims wet while drilling; a dry diamond rim dies fast.

Storage

Keep bits in a case or rack — rattling in a drawer blunts the edges.
Wipe oily shanks, separate wood bits from metal bits, replace worn chucks early.

🔧 THE DRILL MACHINES

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Hand Drill & Brace

Manual, slow, total control. The brace + auger is the traditional way to bore deep timber holes.

Power Drill

Corded or cordless, keyed or keyless chuck, often a 2-speed gearbox. Handles nearly every bit here.

Hammer Drill

Adds rapid light percussion — good for masonry bits up to ~13 mm in brick and block.

Rotary Hammer (SDS)

Pneumatic hammer with SDS shanks — big masonry holes, cores and chiselling.

Pillar / Bench Drill

Fixed vertical spindle, depth stop, adjustable speeds. Square, accurate, repeatable holes — best for metalwork.

Magnetic Drill

Clamps magnetically to steel and drives annular cutters — large, precise holes in beams and plate.

📖 GLOSSARY

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Shank — the end gripped by the chuck (round, hex, SDS, Weldon).

Flutes — the grooves that carry waste out of the hole.

Swarf — the waste material a bit removes.

Point angle — the angle at the tip; 118° standard for metal.

Pilot hole — a small starter hole drilled before the final size.

Countersink — a cone recess letting a screw head sit flush.

Counterbore — a flat-bottomed recess for a bolt head.

Chamfer — a cut-away edge or corner, usually 45°.

Deburr — to remove the sharp burrs left around a hole.

Run-out — wobble of a bit in the chuck; causes oversize holes.

Cutting fluid — lubricant/coolant for drilling metal.

HSS — high-speed steel — hard, heat-resistant bit steel.

Carbide (TC) — tungsten carbide, the hard tip material for masonry/tile bits.

SDS — a splined shank system that locks into rotary hammers.

Weldon shank — a flat-sided shank for magnetic-drill chucks.

RPM — revolutions per minute — how fast the bit spins.

Chuck — the jaws that grip the shank.

Arbor — the central spindle a hole saw or core bit mounts on.

Annulus — a ring-shaped cut — what hole saws and core bits make.

Breakthrough — the moment the bit exits the far side — grab city.

Feed — how fast you push the bit into the work.

🧮 INTERACTIVE TOOLS

RPM SPEED CALCULATOR

PILOT HOLE FINDER

TAP DRILL CHART

🎯 KNOWLEDGE QUIZ

🛠 WORKSHOP GUIDE