Definition
A rotary cutting tool used to enlarge, smooth, and finish a previously drilled hole to a precise diameter. A reamer removes a small amount of material to bring the hole to its final size with a clean, accurate surface, rather than cutting the hole from solid metal as a drill does.
Plain English
A tool that finishes a hole that has already been drilled, making it exactly the right size and smooth on the inside.
Context Anchor
Seen in aircraft maintenance, especially when preparing accurate holes for bolts, pins, bushings, or close-fitting hardware.
Derivation
From the Old English 'ryman,' meaning to widen or make room. The tool widens an existing hole rather than creating one.
Why Pilots Care
Properly reamed holes ensure that bolts, bushings, and pins fit with the correct tolerance. A loose or oversized hole in a critical structure can lead to fastener wear, fretting, or failure.
Intuition Check
A reamer does not drill a hole from scratch. It finishes a hole that is already there, making it round, smooth, and exactly the right size.
Example Sentence 1
After drilling the bolt holes slightly undersize, the mechanic used a reamer to bring them to the final specified diameter.
Example Sentence 2
After drilling the new rivet holes, the technician reamed each one to remove burrs and ensure a flush fit.