Importance

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Abstract

A blade-type rotary drill bit having radially divergent cutting blades arranged in two arrays and equipped with cutting blanks having upset cutting surfaces formed of an abrasive material such as diamond or the like. The blades in one array cut to the center of the bit to provide a conically shaped core volume and the blades of the second array terminate short of the axis of the bit to define a somewhat larger core volume. The bit is equipped with discharge ports and baffles whereby drilling fluid issuing from the discharge ports moves downwardly and then inwardly to the center of the bit. The cutting blanks located on the second array of blades cut in a common set of tracks which are at least partially different from and compliment the tracks cut by the cutting blanks on the blade of the first array.

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First Claim