Abstract: The disclosure relates to a tool consisting of a tool body and cutter bits which are each secured in a slot in the body. By means of a tension screw which engages with the end portion of the bit located most proximal the bottom of the slot, the bit is fixedly retained in the slot under the application of a torque, the bit engaging with the slot walls at, in particular, three points; namely a point on the chipping face of the bit above a clearance disposed between this face and the slot face adjacent the bottom of the slot, a point on the rear face of the bit adjacent the periphery of the tool body, and, finally, the bottom of the slot. The tension screw engages with a surface on the bit which is located beneath a plane at right angles to the longitudinal direction of the bit through the abutment point on the chipping face of the bit, the surface preferably making an angle of approximately 45.degree. with this plane.