What is a Drill Chuck?

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  • Written By: J.S. Metzker Erdemir
  • Edited By: Bronwyn Harris
  • Last Modified Date: 13 October 2018
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A drill chuck is the part of a drill that holds the rotating bit. Drill chucks are designed to hold the bit tightly and not loosen even when there is a high amount of torque. They can also be used to hold other types of rotating tools, such as screwdrivers or rotating spades for making large holes. Drill chucks can be keyed or keyless, depending on the preference of the user and the requirements of the tool.

A keyed drill chuck requires a removable key to open and close it. The key is a T-shaped tool that is inserted next to the chuck. When the chuck key is turned, it moves a gear that makes the collar rotate around the jaws to open or close them. A keyless drill chuck works on a similar principle, but instead of a key, the user turns the chuck with a sleeve at the end of the drill to open and close the jaws. Some people prefer keyless chucks, especially for home power drills, because the chuck key can easily be misplaced. However, a keyed chuck can hold the bit more tightly since it gives more torque and can be tightened by hand more efficiently using less force.


Some drill chucks have up to six jaws, depending on how thick the surfaces are that the drill needs to penetrate. The more jaws a chuck has, the stronger it is. Four jaws are needed in a drill chuck that will hold a square bit. Most power drill chucks for home use have three jaws, and they are self-centering. This means that the three jaws move inwards and outwards evenly to grip a round bit and hold it straight. Drill chucks with independent jaws are used to hold oval bits, or in specialized jobs that require a great deal of precision in centering the bit.

A self-centering drill chuck works with a rotating collar much like a nut. The threads on the inside of the collar are angled so that when the collar is turned, it creates a motion that moves the jaws together. This design is very advantageous for a drill because it allows a user to open and close it easily, but it will not open easily from the torque of the drill. Some drill chucks have an auto-tightening feature which is designed to become tighter when the drill suddenly encounters a surface requiring increased torque.


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Post 4

My current drill has a keyless chuck. I think it is much faster than having to put the bit in and tightening it with a key. I don't do any extreme drilling with it, but I think a keyless chuck would be fine for any normal home projects.

I recently bought my mom a drill that has a special chuck system that fits specially designed bits. They have a hex base and just snap into the drill. The angle of the drill can also be changed. Obviously, this isn't ideal for people doing a lot of heavy drilling since you are limited in the bits you can use, but for putting in screws or other smaller tasks, it's perfect.

Post 3

Just a handy note for anyone who is afraid of losing their chuck key. My trick has always been to tie a piece of string to the chuck and connect it to the drill somehow. If you have a drill press, you can tie the chuck to a string, and then get a two-sided magnet to stick to the side of the press and keep the chuck there so it is out of the way.

I have never seen a drill that had four jaws. I can see how it would hold a square bit, but can it still hold a normal round bit, or would the jaws be at too much of an angle?

Where do you even find drill bits that have square bases? Are there special kinds of bits like that?

Post 2

@kentuckycat - I know the feeling. It can be really frustrating. There are a few routes you can take. Since it sounds like you've already been to the stores in the area, I guess I don't need to mention that. You can usually find them online, though.

If you still have the owner's manual, flip through it and see if you can find any sort of specifications as to the key size. From there, you can go to the manufacturer's website and see if they sell replacement parts. If not, find an online store that sells them. The technical name is a Jacob's drill chuck, so look for that.

You should be able to find something that will work. Sometimes you can even find keys with four different sized heads on them.

Post 1

Unfortunately for me, I have a drill with a keyed chuck, but I lost the key. I can still tighten the chuck just enough by hand to use it, but on a couple of occasions, the jaws have loosened while I was drilling through thick pieces of wood.

Is there anywhere online that you can buy new drill chuck keys? I have looked at the home improvement stores around me, but I haven't had any luck. On the same note, do drills have different sizes of gears and key holes? How do I make sure I get the right size if there can be differences?

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