US Patent 10065294 Tool bit

A tool bit includes a hexagonal drive portion, a working end, and a shank interconnecting the drive portion and the working end. The shank includes an outer peripheral surface having a curvature in a plane including a central axis of the tool bit. The outer peripheral surface having the curvature includes a length in the direction of the central axis. A ratio of the length of the outer peripheral surface having the curvature to the length of the tool bit is between about 0.15:1 and about 0.35:1. The curvature is defined by a radius, and wherein a ratio of the radius of the curvature of the outer peripheral surface of the shank to the length of the tool bit is between about 0.08:1 and about 0.75:1.