Patent ID: 6227774
Filing Date: 2001-05-08
Classification: B27G,Y10T

Abstract:
A spade drill bit for use in association with a drill having a direction of rotation, comprising:an elongate shank portion having a central longitudinal axis and one end adapted to engage the drill;a spade portion extending longitudinally from the other end of the elongate shank, the spade portion having opposed spaced apart planar faces and each planar face having a leading face portion, a trailing face portion, a leading shoulder edges, a trailing shoulder edge, a leading longitudinal edge and a trailing longitudinal edge, the spade portion having a twist in the direction of rotation proximate to the leading shoulder edge and the trailing shoulder edge and the twist having a smooth continuous curve in the longitudinal direction and a rake angle of 6 degrees and the twist of each planar face being arranged such that a straight line perpendicular to the central longitudinal axis from the leading longitudinal edge to the opposed trailing longitudinal edge will be in continuous contact with the respective face; anda centre spur extending outwardly from the spade portion along the central longitudinal axis.