A drill having inner and outer indexable cutting inserts for forming a hole in a workpiece. The inner insert is positioned at a non-negative radial angle and is set out axially ahead of the outer insert to increase the service life of the inserts. Tungsten carbide wear strips are spaced angularly around the drill body to limit radial movement of the body and to prevent the body from wearing.

A tool for cutting or reaming a counterbore in a workpiece is guided by a pilot member secured in a bore. The tool includes a rotatable blade holder having a plurality of attached cutter blades. One of the cutter blades has a lateral cutting edge at a pre-selected radial distance from the rotational axis of the blade holder. The remaining cutter blades do not include lateral cutting edges. Consequently, the lateral or diametral dimension of the counterbore is defined by a single blade. This arrangement substantially prevents oversizing of the counterbore.

A single flute drill having a single, replaceable cutting insert which can drill from the solid, as well as being used for other single point machining operatings such as turning, internal and external diameter boring, contouring and facing. The insert is configured and related to the drill body so as to provide a single, radially extending cutting edge which has an effective neutral rake and negative lead. A specific insert structure is also provided for use in the drill. The disclosed insert comprises a solid body having parallel upper and lower faces each generally in the shape of an equilateral parallelogram and joined along their peripheral edges by side walls. One cutting edge is formed along the juncture of one side wall and the upper face and is inclined along its length toward the lower face. A second cutting edge is formed along the juncture of the lower face and a second side wall which intersects the first side wall at a corner. The second cutting edge is inclined along its length from the corner of the intersection toward the upper face.

An indexable insert drill employing a pair of radially opposed inserts having either positive or negative axial lead cutting edges extending in the same cone of revolution. One of the inserts has a radially inner arcuate corner intersecting and extending across the axial center line. The other insert is located relatively overlapping but outward radially with an outermost corner adapted to finish cut the side wall diameter of the hole. Insert cutting edges provide for chip interruption and breakage.

An indexable insert drill particularly suited for use in machining soft metals such as aluminum or the like. The drill includes an elongated body having a drilling portion with at least one groove extending axially along a portion thereof from the drilling portion end. In one embodiment, a generally triangular cutting insert is fixedly mounted in a receiving pocket included in the groove so that in cutting presentment, the insert cutting edge extends radially of the drilling portion from an innermost end area at the drilling portion longitudinal axis to an outermost end area outwardly of the drilling portion side wall. The cutting insert is configured so that the cutting edge will have neutral lead, neutral radial rake and positive axial rake when the insert is mounted in the receiving pocket. The receiving pocket includes a back tapered side wall defining an insert retaining area for conveniently capturing a side of the cutting insert. In another embodiment, the body drilling portion includes a pair of grooves and a cutting insert associated with each in a manner such that the cutting edges are disposed diametrically across the body drilling portion in a radially and axially offset relationship. Preferably, the inserts used in both embodiment each have a pair of cutting edges which may be selectively placed in drilling presentment. When one of these cutting edges is in cutting presentment, the other is captured in and protected by the insert retaining area of the associated receiving pocket.