When removing the rivet shank, the pin punch should be what size compared to the diameter of the rivet shank?

When removing the rivet shank, the pin punch should be one size smaller than the diameter of the rivet shank. This is crucial because using a punch that is slightly smaller allows for the punch to engage the rivet shank without causing undue damage to the surrounding material or the rivet itself. A smaller punch can fit through the hole in the rivet head more easily, minimizing the risk of jamming or bending the punch.

Additionally, a properly sized punch will allow for easier and more controlled driving of the rivet shank, ensuring that it is removed cleanly. If the punch were the same size or larger, it could lead to issues in maneuverability and may create excessive stress on both the punch and the rivet, potentially making removal more difficult or damaging the workpiece. Therefore, selecting a punch that is one size smaller is the optimal choice for effective and safe rivet removal.