Patent ID: 7396287

Claim:
A method of manufacturing a multi-grip blind rivet, the method comprising: placing a mandrel through a shell, the mandrel abutting against a blind end of the shell and having a head and a stem extending from the head, the stem having a point of weakness part way along its length and disposed within the shell, the shell having an outwardly extending flange at one end forming a rivet head; crimping the shell around the periphery of the shell at a first distance from the shell flange so as to form a first plurality of radial indentations such that when viewed in cross section through the length of the indentations the radial indentations are arc shaped; and crimping the shell around the periphery of the shell at a second distance from the flange so as to form a second plurality of radial indentations such that when viewed in cross section through the length of the indentations the radial indentations are arc shaped, and so as to cause the hardness of the shell is between about 20% and 30% higher than the hardness of the shell at a point mid way between the first plurality of indentations and the second plurality of indentations, said shell being configured to plastically deform at the midway point during setting.