Centre Punch

Description

Centre Punches are ground to a strong point with an included angle of 90 degrees by holding them Tangentially to a Tool Grinder and rotating them. This tends to create grinding marks which run along the point and strengthen it rather than weakening it by going across (i.e. in a similar manner to a Scriber).

Features and Uses

To stop a drill bit skidding about a metal surface, these are used to make a small indentation to locate the drill centre.

Note: Hold the punch to an angle to position on centre then raise to the vertical and strike it sharply with a hammer - but only once - striking several times may cause the punch to bounce around.

DT Online Buyers' Guide

The lowest cost option is to use a hand-held punch with a hammer but a wide range of automatic punches are available - both Dot Punches and Centre Punches.
In general, Dot Punches have a sharper point (i.e. 60° instead of 90°) and need only the lower ranges of impact force (e.g. 20N to 50N).
Automatic punches are simply pushed down against the work-piece and do not need to be struck - indeed, should NOT be struck with a hammer.