Manual locking means for bit holder with micro/macro adjustment

Locking means for a bit holder fixture for use with grinding apparatus for grinding hard metal inserts of rock drill bits, wherein the bit holding fixture has an end wall and the locking means comprise an assembly having a pressure plate with a first face facing the bit when the bit is inserted between the first face of the pressure plate and the end wall of the bit holder fixture, with macro adjustment means for positioning of the pressure plate against the body of the bit(s) with the body of the bit(s) in contact with the end wall and a micro adjustment means moveable relative to the macro adjustment means from a first position to a second locking position to lock the bit(s) in place by applying pressure against the pressure plate to retain the skirt or shank of the drill bit(s) in place against the end wall.