What is a Chuck on a Drill –

A drill chuck is a spindle mounted device on a drill that can clamp drill bits and attachments for the main purpose of drilling holes or fixing screws. They are either keyless, operated with a drill chuck key or use a hybrid system. A drill cannot be used effectively unless it has a working chuck.

The vast majority of drills or drill/drivers use what is called a single sleeve chuck. Heavy duty hammer drills tend to use keyed chucks, where the chuck is tightened and loosened by using a “chuck key.”

Types of Drill Chuck Explained

There are six types of drill chucks:

1. A Keyed Chuck
2. A Single Sleeve Keyless Chuck
3. A Double Sleeve Keyless Chuck
4. An SDS Chuck
5. Hex Connection Chuck
6. Hybrid Chucks

Drill Chuck Sizes

The maximum size of a drill or screwdriver bit that can be inserted into a drill is absolutely determined by the chuck size. The size of the chuck required will frequently be determined by the function for which it will be used. The size of the chuck determines the drill’s maximum drill bit diameter.

The shank diameter of a bit is the measurement across the centre of the shank. Hexagonal shanks are measured across their flats. The measurement for a round shank’s diameter can be taken from any point around the circumference.

Drill chucks come in two main standard sizes:

• 10mm (3/8″)
• 13mm (1/2″)

For most general types of drilling the 10mm chuck is a good choice. For heavier drilling, or if you need to drill larger holes, it is better to get a drill with a 13mm chuck as that allows you to cater for thicker diameter drill bits.

How does a Drill Chuck Work?

There are several parts to drill chucks. These include:

• Sleeve – this rotates around the body and will turn the ring nut
• Gear teeth – interlocks with the jaw’s teeth
• Body – the purpose of this is to position the jaw’s movement
• Jaws – these are what clamps the accessories
• Outside Shell – this holds the moving parts
• Some may also have a key and ring nut – the ring nut turns and the teeth interlock with the jaw’s teeth

The arbor is a tapered shaft that fits into the spindle of the power drill. The jaws are spring-loaded and fit around the arbor. The key or chuck key is used to tighten or loosen the jaws so that the drill bit can be secured in place. When the chuck key is turned, the jaws move inward or outward to grip the drill bit. When the drill is turned on, the arbor rotates and the jaws hold the drill bit firmly in place, allowing for precise and accurate drilling.

With keyless chucks no key is used and the chuck is simply tightened by hand.

Common Problems with Drill Chucks

Wear and Tear 

Usually the main problem is simply wear and tear. The teeth wear over time and the jaws weaken over time. That means the chuck can’t hold bits properly and it will start to slip. Teeth also wear out on the chuck and it starts to stick. They are difficult to repair and it is better to replace the chuck.

Drill bits slipping

If you start to notice your drill bits slipping this is because the chuck is not tight enough. With a keyed chuck you simply need to tighten the chuck some more. With keyless chucks you can try to tighten by hand. If that doesn’t work then it is likely the chuck is reaching the end of life and will need to be replaced.

Dirt and dust

Over time chucks can get dirty from a mixture of dust and/or fragmented pieces of material. It is always worthwhile using a small brush to try and clean out any dust or debris in the chuck. It is limited in how much you can do but it is always a good maintenance job to do every now and then.

How to Install a Drill Chuck?

You will need to get a replacement chuck from the brand for your exact brand and model of drill. If you can do that, it will be cheaper than buying a replacement drill. Good drill brands always have chucks available as spare parts. You may also be able to find chuck replacements on auction sites such as eBay.

Before removing the old chuck, make sure it is not plugged in. If it is a cordless drill then disconnect the drill’s battery pack. Most chucks have a threaded spindle chuck.  Open the jaws as far as you can and remove the left-hand thread screw if there is one.

You can then attach a hex-type wrench into the chuck’s body and tighten it up. Using a mallet, hit the wrench counterclockwise and unscrew the chuck. You can then attach the new chuck, tighten the jaws with the wrench and hit the wrench again with the mallet to tighten it fully.

For tapered shank arbors, open the jaws until they are retracted into the chuck and place the chuck nose inside. Rest it on a flat surface and hit the tang of the arbor lightly to seal this into the new chuck.