Rock drill bit having shaving cutters (38) on the leading end of a removable bit head (20) for shaving the hole bottom and shaving reamer cutters (54, 66) extending lengthwise of the bit. The cutters and receiving slots therefor have dovetail configurations for trapping the cutters in the slots. Wedges for locating the cutters are disposed in the bottoms of the slots. Lateral passages (82, 83, 84) communicate with a central mud passage to deliver mud fluid to ports between the cutters. The central mud passage has a venturi configuration (24C) and lengthwise extending passages (86) in the bit extend downwardly from upstream of the venturi to intersect or communicate with the lateral passages. A core shaver (102) is mounted by a collet chuck (100) in the central passage close to its outlet to the leading end of the bit to shave a core formed on the hole bottom between the inner ends of the shaving cutters (38) on the end face.
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