Definition
The shape of a chisel or drill point that has been ground with a concave (cupped) face rather than a flat one. On a cold chisel or similar tool, the cutting edge is hollow-ground so the center of the edge is set back slightly from the corners, producing a curved cutting line that bites into the work more cleanly.
Plain English
A chisel or drill tip that has been sharpened so the cutting end is slightly hollowed out, like the inside of a shallow cup, instead of being ground flat.
Context Anchor
Seen in aircraft maintenance when describing set screws or small threaded fasteners used to hold parts in position.
Derivation
From 'cup' (a hollow, rounded shape) and 'point' (the working tip of a tool). The name describes the shape of the ground surface — the tip is hollowed like a small cup rather than ground flat.
Why Pilots Care
A loose setscrew can allow critical flight controls or engine parts to shift, creating a safety risk during flight.
Analogy
It is like pressing the rim of a tiny metal cup into soft material: the edge leaves a ring-shaped mark and helps resist movement.
Intuition Check
Cup point does not mean a sharp point. Here, point means the working end of the screw, and cup describes its hollow shape.
Example Sentence 1
The mechanic used a chisel with a cup point to shear off the damaged rivet head cleanly.
Example Sentence 2
During the inspection, verify that all cup point setscrews on the mixture control are properly tightened.