Definition
A cutting tool used to enlarge and finish a hole so that its diameter changes gradually along its length, producing a smooth, conical (tapered) bore to a precise size. Taper reamers are used in aircraft maintenance to prepare holes for taper pins and to clean up tapered holes in fittings.
Plain English
A hand or machine tool that shaves a hole into a cone shape, where one end of the hole is slightly wider than the other, and leaves the inside walls smooth and accurately sized.
Context Anchor
Seen in aircraft maintenance, especially in sheet-metal, structural, and hardware work where holes must fit pins or fasteners accurately.
Derivation
‘Reamer’ comes from the Old English ‘ryman,’ meaning to widen or make room. ‘Taper’ refers to a gradual narrowing. Together, the name describes a tool that widens a hole gradually from one end to the other.
Why Pilots Care
Taper pins are used in aircraft to lock parts together precisely, and the holes they sit in must match exactly. A properly reamed taper hole means the pin seats fully and holds securely, which matters for control linkages and other critical assemblies.
Intuition Check
Do not think of a taper reamer as a drill bit. A drill bit makes the original hole; a taper reamer carefully shapes an existing hole into a gradual taper.
Example Sentence 1
The mechanic used a taper reamer to finish the hole before installing the taper pin in the control linkage.
Example Sentence 2
After drilling, a taper reamer ensures the fastener seats evenly and holds the structure firmly.