An Overview of Chuck Tools

Posted on Jul 28, 2021

Chuck Tool

Many chuck tools have jaws that are symmetrically designed like the points of a star. The jaws are tightened up to hold a workpiece or object, or loosened with the assistance of a chuck key, which is a tool that looks like a wrench made for the purpose.

A chuck tool is a special kind of clamp that holds a workpiece using radial symmetry. It is used to hold the rotating workpiece on a milling, drilling, or lathe machine. Chuck tools on some lathes also have jaws that move independently, allowing them to hold circular or irregularly shaped objects. Some more complex chucks even involve specifically shaped jaws, a higher number of jaws, a quick-release mechanism, or other distinct features.

How Do Chuck Tools Work?

Different types of chuck tools can have different numbers of jaws. But however many jaws there are chuck tools all work on similar principles. To start, the body of the chuck is to position and guide the movement of the jaws as they come together or are separated. The sleeve or e shell rotates around the body of the chuck. As the sleeve is turned, the ring nut is turned as well. The teeth of the ring nut interlock with the teeth on the jaws; as the ring nut turns, the jaws move forward or backward to become together or apart, guided by the body of the chuck. If the shell is rotated clockwise, then the jaws come together clamping the drill bit in place; if rotated counter-clockwise, the drill bit will be released moving the jaws apart. 

Figure 1. Chuck Tool on a Lathe Machine

Some chuck tools need to use a key to turn the sleeve and are therefore called keyed chucks. Nevertheless, most hand drills and braces utilize a chuck without keys, where the sleeve or shell is tightened by hand. The advantage of using a keyed chuck on your hand drill is that the key allows you to apply more torque to the chuck, which holds the jaws tight enough to ensure a secure grip on the drill bit; this reduces the likeliness of it slipping in the chuck. Lastly, capacity and size are the general parameters that you will see in the product specification. The capacity and size of a chuck indicate the maximum size of drill bit that the chuck can hold.

Types of Chuck Tools

In this section, the most commonly used chuck tools are introduced: three-jaw universal chuck, independent chuck, magnetic chuck, and collet chuck.

Three-jaw Universal Chuck

A three-jaw universal chuck is used to hold irregularly shaped workpieces like round and hexagonal objects. It clamps the work rapidly and within a few hundredths of millimeters or thousandths of an inch of accuracy. This is because the three jaws move at the same time when adjusted by the chuck wrench. The simultaneous motion is attributed to a scroll plate into which all the jaws fit. Three-jaw chucks are designed in various sizes. They normally come with two sets of jaws: one for inside and one for outside chucking.

Figure 2. 3 Jaw Lathe Chuck

Independent Chuck

Independent chucks typically have four jaws, each of which can be adjusted by a chance wrench. They are often used for holding round, hexagonal, square, and irregularly shaped objects. The jaws can be reversed to hold the workpiece by the inside diameter. The independence of the jaws also makes centering objects highly controllable but sacrifices speed and ease of use. Four-jaw independent chucks can be found on lathes and indexing heads, and are almost never used for tool holding. Self-centering chucks sometimes incorporate the four-jaw mechanism as well. Though, they often are unable to hold hexagonal or oval objects.

Figure 3. Independent Chuck

Collet Chuck

Collet chucks are the most accurate type and are used for highly precise operations and small tools. The spring collects in the chuck are available to hold round, square, or hexagonal objects. An adapter is placed into the taper of the headstock spindle, and a hollow drawbar with an internal thread is installed in the opposite end of the headstock spindle. As the handwheel and drawbar are revolved, the collects are drawn into the tapered adapter, causing the collets to tighten on the work objects.

Figure 4. Collet Chuck

Magnetic Chuck

Magnetic chucks are used to hold steel or iron parts that are too thin to be held or could be damaged if otherwise held by a conventional chuck. They are fitted to an adaptor mounted on the headstock spindle. Workpieces are held lightly for aligning purposes by turning the chuck wrench approximately by a quarter.

Figure 5. Magnetic Sine Chuck


Faceplates are used to hold workpieces that are either too large or too irregularly shaped so that they cannot be held between the jaws. Faceplates are designed to have several slots to allow the use of bolts to secure the workpiece so that the axis of the workpiece may be aligned with the lathe centers. When the workpiece is mounted off-center, a counterbalance should be secured to the faceplate to prevent imbalance and the resulting vibrations when the lathe is in operation.

Figure 6. Faceplates with Slots

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