continue serving to limit wear to the drill bit shank at the full gauge preventing excessive wear on the edge of the drill bit as drilling continues into the bore pdc buttons 42 can be inserted around the full diameter of the drill bit shank to minimize wear of the bit from the bore wall these wear buttons 42 can be placed at a variety of positions along the drill bit shank in a manner well known in the art fig8 is a cross sectional view of the rotary drill bit bore hole face b showing the scoured grooves g rubbed in the face of the bore by the rotary movement of the pdc cutters in each distinct groove here pdc cutters of line 4 4 more clearly shown in fig1 and 4 are shown scuffing grooves in the bore face b the peaks p and p u2032 formed between the successive grooves g disintegrate and crumble when the central cutter 16 and adjacent cutters 22 22 u2032 28 and 28 u2032 score the interior surfaces of each groove allowing the rock to be swept from the bore hole by the flushing drill fluid directed at them similar action of grooving peak fracture and removal occur on the alternative cross sectional planes of cutters shown in fig5 7 the forward motion of the drill bit into the bore b continuously deepens each groove g thereby causing crumbling and fracture of the alternative peak points p and p u2032 which are rapidly removed from the drill bit face by the hydraulic sweep of the jetting nozzles the swarf examined from tests run with this bit show.