Screw driver

Claim 1

A screw driver comprising a shank portion terminating in four blades integral therewith, each of said blades tapering, diminishing in thickness, as it extends downwardly to form a point at an extension of the longitudinal axis of said shank portion and each terminating in a lower foot engageable with the bottom portion of a slot of a cross slotted screw head, each of said feet portions protruding outwardly from its respective blade faces to provide a gripping means engageable with opposed sides of a screw slot to removably hold a screw thereon and also to cut a groove in the parallel sidewalls of a screw-head slot upon application of a torque to said shank, said feet portions each defining the lower most portion of its respective blade and being generally isosceles trapezoidal in transverse cross section with its base being most remote from said extension of said longitudinal axis of said shank and lying in an outwardly bowed arcuate plane which extends from the periphery of said shank portion toward an extension of the longitudinal axis of said shank portion, each of said feet portions intersecting with the other feet portions to form a point and each having its inwardly tapered sidewalls extending along the entire length of its respective blade to be engageable with the parallel sidewalls of a screw head slot, said base of each of said feet portions and its respective inwardly tapered sidewalls defining wedge-like bites comprising said gripping means.