A rotatable tool includes a shaft and a cutting head mounted thereto. The shaft defines a longitudinal axis of rotation and has a seat formed at a front end thereof which includes a first engagement surface. The cutting head is attached on the seat and includes a second engagement surface engaging the first engagement surface for longitudinally locking the cutting head to the shaft. The first and second engagement surfaces include respective first and second support surfaces which together form a planar interface, the interface defining a contact line when viewed longitudinally toward a front end of the tool. The contact line intersects an outer periphery of the cutting head at a point. The contact line extends from the point in a direction forming an acute angle with a radius that intersects the point. The contact line is disposed rotationally ahead of the radius with reference to rotation of the tool. The cutting head is attached to the shaft in response to relative rotation therebetween, whereupon respective longitudinal undercuts formed by the support surfaces engage one another, and a snap action occurs between respective portions of the engagement surfaces, to resist longitudinal and rotational dislodgement of the cutting head.

A drill including a shank portion and a cylindrical body portion contiguous to each other. The cylindrical body portion includes (a) primary cutting edges and secondary cutting edges formed in its axially distal end portion such that each of the secondary cutting edges is located on a radially inner side of the corresponding primary cutting edge; (b) primary rake surfaces of the primary cutting edges and secondary rake surfaces of the secondary cutting edges; and (c) inclined surfaces each of which extends from the corresponding secondary rake surface to a periphery of the cylindrical body portion, and is inclined such that an axial distance between each of the inclined surfaces and the shank portion is reduced as viewed in a direction substantially perpendicular to the corresponding secondary cutting edge, from the corresponding secondary rake surface toward the periphery of the cylindrical body portion. Each of the secondary rake surfaces and the corresponding secondary cutting edge are formed together with each other in a web thinning. Each of the secondary rake surfaces and the corresponding inclined surface are connected to each other without a step therebetween.

A drill bit for use in association with a power or hand drill comprising a drill bit head and shaft. The drill bit head includes a drill bit cutting head and a guide point. The drill bit cutting head includes a first and a second cutting vane. Each cutting vane includes a first cutting edge which extends perpendicular to the axis of rotation and is provided for removing workpiece material, a second cutting edge which extends parallel to the axis of rotation and is provided for forming a substantially smooth workpiece bore, and a channel for facilitating the expulsion of removed workpiece material away from the first cutting surface as the drill bit passes through the workpiece.

The present invention relates to a drill having an aggressive drill point geometry. The point geometry allows greater stability and feed rates, while decreasing the heat generated at drill point. The present invention is provided by a drill comprising drill body having at least two helical flutes, a pair of cutting surfaces on an end of the drill body, a web formed between the two cutting edges, and a web thinning notch formed on either side of the web. Each notch forms a notch cutting edge having a positive rake angle.

A metal cutting drill bit has a shank portion, a flute portion defining a helix angle and a tip. The tip has a primary cutting edge extending to an outer periphery of the drill bit. The primary cutting edge has a rake face defining a rake angle. The rake angle is different from the helix angle at the tip of the drill bit.