A clinching tool including a punch and a die assembly. The die assembly includes a collet and a pin. The collet is formed of bar stock and includes a lower central knock out bore and an upper central pin bore coacting at their juncture to form an annular seat within the collet. A plurality of circumferentially spaced axially extending slots are formed in the annular collet wall surrounding the upper pin bore to define a plurality of cantilevered collet fingers having their free ends at the upper end of the collet. The pin has a diameter approximating the diameter of the pin bore and a length slightly less than the length of the pin bore and is fitted in the pin bore with its lower end seated on the annular shoulder between the pin bore and the knock out bore and with its upper end spaced slightly below the upper ends of the collet fingers.
