What Is a Reduced Shank Drill Bit Set?

A reduced-shank drill bit--note that the diameter of the non-cutting end has been reduced to allow it to fit into smaller chucks.

Drill bits are sharp, hardened metal devices designed to bore into wood, metal, or other material. Bits are mounted in electric or hand-powered drills which create rotation of the bit, allowing it to work.

Twist Bits

Twist bits, also called twist drills, are slightly pointed cylinders with fluted edges. Pressure on the bit forces the tip into the work piece. The flutes carry away waste material, and their sharpened edges ream the hole to a constant diameter. Bits come in a wide range of sizes, from 1/32 of an inch to over an inch in diameter. Typical bits have the same diameter from end to end, except for the point at the cutting end.

Drill Chucks

Twist drills are fixed into a hand or power drill with a chuck. A chuck's design allows it to adjust to hold a range of bit sizes from very small up to a specific maximum size. Consumer drills usually have a 3/8-inch chuck while contractor-grade drills may have a 1/2-inch chuck.

Reduced Shanks

A reduced-shank bit is designed to allow insertion into a chuck even if the bit diameter is larger than the chuck's maximum opening. The last few inches of the bit shaft opposite the cutting end are machined to a preset size, usually 3/8 or 1/2 inch. This allows a drill with a 3/8-inch chuck to accept a bit of larger diameter, such as 5/8 or 9/16 inch.

References

• DIY Data: Drill Bits
• Crazy Builders: How it Works: Drill Chuck
• Aubuchon Hardware: Drill Bits -- Reduced Shank