Abstract: A self-tightening drill chuck adapted to be mounted on a drill spindle for rotation about and reciprocation along the axis of the spindle has a guide body rotatable on the spindle about the axis and formed with a plurality of jaw guides inclined relative to the axis and spaced angularly thereabout and formations axially fixing the guide body on the spindle against substantial relative axial displacement. Respective jaws displaceable in the guides are formed with radially directed teeth meshing with a screwthread of an adjustment body fixed on the spindle against rotation thereon so that rotation of the adjustment body relative to the guide body in one direction displaces the jaws radially toward one another and opposite rotation displaces the jaws radially apart. Further formations secure the adjustment body on the spindle for limited relative axial displacement substantially greater than the relative axial displacement possible between the guide body and the spindle.

Abstract: A cutting tool such as a body drill has a cylindrical shank portion and a body section connected to the shank portion. The twist section terminates at a cutting end. A pair of flutes are formed in the body section, defining a land therebetween. The land includes a narrow margin having a width between 0.015 and 0.025 inches. The land also has a body clearance of a diameter less than that of the margins. The flutes terminate at flute faces at the cutting end. The flute faces are disposed parallel to each other at a zero degree rake angle. The narrow margin aspect of the invention could also be applied to a counterbore or spotface.