Keyed or keyless chuck — which is better, and what does 13mm mean?

The chuck is the part of the drill you interact with most and think about least. There are only three variables worth understanding, and each one explains a frustration people usually blame on the drill.

Step by step

1. Understand what the capacity figure means.10mm or 13mm is the maximum shank the jaws will close on. A 13mm chuck does not drill 13mm holes as a limit — a 25mm spade bit with a reduced 8mm shank fits a 10mm chuck perfectly well.
2. Know why 13mm is preferred.Larger bits, hole saw arbors, mixing paddles and adaptors frequently have shanks over 10mm. A 10mm chuck quietly rules out a range of accessories you do not know you want yet.
3. Recognise a keyed chuck's advantage.A key gives leverage, so the jaws clamp far harder than a hand can manage. Under heavy sustained torque — big bits, hole saws, corded drilling — a keyed chuck does not let the bit spin.
4. Recognise the keyless advantage honestly.You change bits in three seconds without hunting for a key, which in practice means you change bits when you should rather than making do with the wrong one. For most people that improves the work more than grip does.
5. Learn the single-sleeve and two-sleeve difference.A single-sleeve chuck has a spindle lock so one hand tightens it. A two-sleeve chuck needs one hand on the rear collar and one on the front. Two-sleeve chucks are often tightened badly because people use only the front, and then blame the bit for slipping.
6. Tighten a keyless chuck properly.Push the bit fully back between the jaws before tightening, so it is gripped along its length rather than on the jaw tips. Then tighten hard — you should hear the ratchet click over, which is the mechanism seating, not a warning.
7. Use all the holes on a keyed chuck.Most keyed chucks have three key holes. Tightening in each one in turn seats the jaws evenly, which is the difference between a bit that runs true and one that does not.
8. Match the chuck to the work, not the fashion.For a household drill, keyless every time. For a bench drill, a mixing drill or an old corded workhorse used with big bits, a keyed chuck is a better tool.

Tips

• Attach the key to the drill's lead with a small clip. A keyed chuck whose key is missing is much worse than a keyless one.
• Hex-shanked bits grip far better than round ones in any chuck, because the jaws bear on flats rather than on a tangent. If a specific bit keeps slipping, a hex-shank version usually solves it.
• Never tighten a chuck with pliers or a wrench on the sleeve. It marks the sleeve, does not improve the grip much, and damages the mechanism.

Common mistakes

• Buying a drill on chuck capacity as if it were a power rating — Capacity limits shank size only. Motor, gearbox and battery determine what the drill will actually bore.
• Tightening a two-sleeve chuck by spinning only the front — The rear collar turns with it and the jaws barely move. Hold the rear, turn the front.

Questions people ask