US Patent 6849004 Golf-putters

A golf-putter head (1) has a grooved impact face (5) defining lengthwise ridges (7) for impacting a dimpled golf-ball in areas of contact that are distributed around the dimples for improvement of putt accuracy by collectively centralizing the resultant striking force on the ball. The profile, width w and pitch p of the ridges (7) are selected according to hardness h and with p and w not exceeding 3.5 mm and (p−0.4) mm respectively, to reduce the standard deviation of dimple-effect error distribution by at least 15% in putting with initial ball-velocity of 2.5 m/s. Ridge-profile is symmetrically rounded (FIGS. 2,4,5,21), flat (FIG. 6,20) or segmented-flat (FIG. 3), or asymmetrical (FIG. 19), and test apparatus (FIGS. 11, 12) uses a linear actuator (33) for projecting the ball repeatedly to drop onto an impact-recording plate (36) to reveal scatter due to dimple-effect error.