Drill chucks are devices used to hold a drill or other cutting tools on a spindle. They are available in keyed, keyless or hybrid systems, allowing for quick changes of a drill bit.
Diagram of a Drill Chuck
Key Styles:
Keyed chucks are engineered to either loosen or tighten the hold on a tool by using a key. Keyed chucks offer the advantage of applying additional torque on the bit when slippage is a concern during heavy-duty applications.
Keyless chucks are engineered to quickly loosen and tighten a tool on the chuck collar of the drill, either by manual operation or when torque is applied. Rotating the chuck collar in a counterclockwise direction will loosen the tool.
Hybrid drill chucks are engineered with both keyed and keyless systems. The keyless portion automatically tightens, while the keyed portion is adjusted on the chuck to offer added gripping and torque support on the tool.
Mount type refers to how the drill chuck connects to an arbor, shank or spindle.
Integral Shank drill chucks are designed with the arbor (shank) built into the drill chuck, providing greater rigidity and concentricity than a press-fit tapered mount.
Tapered Mount drill chucks have an internal Jacobs Taper (JT) that is press-fit onto a corresponding JT arbor (shank) or spindle.
Threaded Mount drill chucks have an internal thread for securing to a power drill spindle or a threaded arbor.
Drill Chuck Taper Mount Size
Morse Taper Dimensions | ||||||
|---|---|---|---|---|---|---|
| Morse Taper | 1 | 2 | 3 | 1 | 2 | 3 |
| D1 | 0.481" | 0.709" | 0.947" | 1.244" | 1.7613" | 2.510" |
Jacobs Taper Dimensions | ||||||||
|---|---|---|---|---|---|---|---|---|
| Jacobs Taper | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 33 |
| D | 0.250" | 0.384” | 0.559" | 0.811" | 1.124" | 1.413" | 0.676" | 0.624" |
Bearing Type: Choosing the right bearing type can be critical for your equipment. The bearings reduce friction in the drill chuck's closing mechanism so more pressure can be applied to grip the drill bit.
Cutting fluids are 90-98% water when diluted, so the chemistry of the water plays a major role in a product's effectiveness.
Ball Bearing: Ball bearings are designed to reduce friction in the tightening mechanism and provide a better grip on the drill. They are used for heavy-duty machining and require a key for tightening or loosening.
Plain Bearing: Plain bearings are designed with a one-piece gearing and sleeve for reducing teeth breakage. They are used for medium-duty operations with stationary drilling, turning, milling and woodworking machines.
Plain Bearing Keyed Chucks: Equipped with one-piece gearing and sleeve that reduces the possibility of teeth breaking. Used for stationary drilling, turning, milling and woodworking machines. For medium-duty industrial use. Available with threaded mount for hand-held drilling machines and with tapered mounts for stationary drilling machines where run-out is not a problem or factor (max. .004″ approx.).
Light-Duty Keyed Chucks: Equipped in most power tools for DIYers for decades, this is a good, inexpensive chuck for light-duty applications. Nowadays, they are replaced by keyless chucks more and more. For electric hand-held drilling machines, reversible or non-reversible.
Stainless Steel Keyed Chucks: Manufactured out of stainless steel. For use in the food, medical and dental industries where tools must be sterilized. Same design as a plain bearing chuck, but in stainless steel.
CNC Precision Keyed Chucks w/integrated shank. Ideal for CNC machines. Short design, maximum concentricity, max. run-out .0012″ or better. High clamping forces, over 75 ft./lbs., and optional through coolant. Permits clockwise and counterclockwise turning. For use in high-speed CNC equipment for milling, drilling, reaming and tapping.
Keyless Chucks for high-precision/high-torque applications: Do not require key for tightening or loosening. Incorporate a self-tightening feature that causes them to grip tighter as more torque is applied. Permit clockwise turning only. Automatic fitting for efficient, fast change tools. Minimum run-out for accurate hole sizing (max. TIR .0016″ or better). For high-accuracy drill presses, jig borers, milling machines and production drilling equipment, CNCs included.
Keyless Chucks for medium-duty applications: Same self-tightening feature as high-precision or high-torque chucks but with wider run-outs (about .006″). Automatic fitting for efficient, fast change tools. For medium-duty industrial use, available with threaded mount for hand-held drilling machines and with tapered mounts for stationary drilling machines. Clockwise turning only.
Keyless Chucks in stainless steel: Manufactured out of stainless steel. High-precision and self-tightening design. For use in the food, medical and dental industries where tools must be sterilized. Clockwise turning only.
Keyless Drill Chucksfor portable drilling machines: These are the latest generation chucks for power tools. Do not require a key for tightening or loosening. Some are equipped with a locking mechanism for hammer drilling and also screwdriver operations (clockwise and counterclockwise). Ergonomic design, offered with plastic or metal sleeves. For hand-held drills, reversible or non-reversible.
CNC Precision Keyless Chucks w/integrated shank: Same as type No. 5, but keyless. Ideal for CNC machines but for applications requiring clockwise turning only as it has a self-tightening feature. Compact construction, maximum connection rigidity, higher precision (TIR .0016″ or better, certified by some producers only). For use on CNC machine centers, milling and turning machines, or other stationary equipment.
Materials:
Stainless steel is a strong, corrosion-resistant alloy with excellent resistance to heat. It is used in high-stress, outdoor and corrosive applications.
Steel is strong and durable but less corrosion resistant than stainless steel. To improve its resistance to corrosion, it may receive additional finishes and coatings.
Mounting & Removing Chucks
On Threaded Spindle Portable Tools
Unplug drill or disconnect battery pack. Open jaws of existing chuck completely. Remove left-hand thread screw, if any, from inside chuck and save for re-use. Insert hex-type wrench into chuck body and tighten jaws on wrench. Strike wrench counterclockwise with mallet to free and unscrew chuck. Screw new chuck onto spindle (clockwise). Insert hex-type wrench in jaws and tighten jaws on wrench. Strike wrench clockwise with mallet several times.
On Tapered Shank Arbors
To mount chucks:
Clean both tapers of all grease and grit. With the jaws retracted into the chuck and with the chuck nose resting on a wooden bench, strike the tang of the arbor lightly to seal it into the chuck.
To remove chucks:
Insert wedge between the back of the chuck and the shoulder of the arbor. In case the mounting taper of the arbor does not provide a shoulder, a cross hole should be drilled through the neck of the arbor and a cross pin inserted. Then the wedge can be used between the chuck back and the cross pin to free the chuck from the arbor.
