Definition
A hand tool with a long, straight, parallel-sided shank used to drive a pin, rivet, or bolt completely out of a hole after it has already been started moving by a starter punch (also called a drift punch). The shank diameter is slightly smaller than the pin being driven, and unlike a tapered punch, the working end stays the same diameter for its full length so it can pass deep into a hole without binding.
Plain English
A straight metal rod, held in the hand and struck with a hammer, used to push a stuck pin or rivet the rest of the way out of a hole.
Context Anchor
Seen in aircraft maintenance procedures and tool lists when small pins, hinge pins, or fitted fasteners must be removed or installed.
Derivation
Punch comes from the Old French ponchon, meaning a pointed tool for piercing or driving. Pin punch simply names the job: a punch made to drive pins. The name reflects the tool's single purpose rather than its shape.
Why Pilots Care
Using the wrong tool can damage the pin, enlarge the hole, or scar the aircraft part. Even if a pilot is not doing the work, the term may appear in maintenance instructions or permitted owner-maintenance tasks.
Intuition Check
Do not picture a tool that makes a new hole. A pin punch is mainly used to push an existing pin into or out of an existing hole.
Example Sentence 1
After loosening the hinge pin with a starter punch, the mechanic switched to a pin punch to drive it the rest of the way out.
Example Sentence 2
Using the wrong size pin punch can enlarge the hole and weaken the joint.