Definition

Noun: A type of drill bit with a cutting blade that can be adjusted to create holes of different diameters. It is designed to expand to a larger size than its starting diameter.

Usage

An expansion bit is a tool used primarily in woodworking. It is inserted into a brace (a hand-powered drill) and adjusted to bore holes of varying widths. The key characteristic is its adjustable cutter.

Examples

• Noun:
  • The carpenter selected an expansion bit to bore the large hole for the door knob.
  • For a clean, adjustable hole in wood, an expansion bit is more versatile than a set of fixed-size bits.

Advanced Usage

• Historical/Traditional Use: Expansion bits were essential tools before the common availability of power drills and comprehensive bit sets, often used with hand braces for furniture and cabinet making.
• Technical Operation: The bit has a sliding, lockable cutter that moves along a central shaft. A setscrew is tightened to secure the cutter at the desired radius, determining the hole's final diameter.

Variants and Related Words

• Expansive bit: An alternative name for the same tool.
• Adjustable bit: A broader category that includes expansion bits and other bits with variable sizing.
• Brace bit: A bit designed to be used with a brace (hand drill); many expansion bits are a type of brace bit.
• Forstner bit: A different type of bit that creates very clean, flat-bottomed holes but is not adjustable like an expansion bit.
• Spade bit: A flat, paddle-shaped bit for quick boring; it is not adjustable.

Synonyms

• Adjustable drill bit
• Expansive bit

Antonyms

• Fixed-size bit
• Solid bit

Noun

1. a bit with a cutting blade that can be adjusted to different sizes