Abstract: A machining apparatus is described, of the type that includes a metal cutting insert which is held by an insert holder apparatus, wherein the insert can be installed in a plurality of different positions to use different ones of the cutting edges, which facilitates mounting of the insert. The holder apparatus includes a holder bar (16, FIG. 1) and a pocket member (14) that mounts on the bar and that holds an insert (12) with cutting edges (22). The pocket member has a first precision flat surface (90) that mounts facewise against a flat surface on the bar, and the pocket member has a second precision flat surface (92) that mounts facewise against a surface on the insert. The first and second flat surfaces on the pocket member can be parallel, or can be angled slightly from each other, to control orientation of the insert. The insert has a mount portion (32, FIG.

Abstract: A threadmilling tool is described, of the type that includes a thread cutting insert 14 (FIG. 1) that mounts on an insert holder 12 which is turned by a milling machine, wherein the insert provides four separate cutting edges 30-36 and can be accurately relocated on the holder. The insert has a cross-section forming a mount portion 50 (FIG. 5) with six straight locating sides 51-56 lying on the sides of an imaginary bisymmetrical polygon 58, and forming a radially outwardly-extending arm 60, 62 at each corner of the polygon. Each arm has an outer border 70 and a pair of opposite sides 72, 74 that extend largely radially from the axis 24 of the polygon, and each arm forms a cutting edge (e.g. 30) at the intersection of the outer border and each side of the arm. A tool holder 16 (FIG. 2) for holding the insert, has walls forming, in cross-section, a pair of straight holder positioning surfaces 80, 82 that abut a pair of insert locating sides, while avoiding contact with the arms 60, 62.

Abstract: A threading insert is provided of a type that includes a mount portion and a plurality of arms radiating therefrom that each forms a pair of cutting edges, which is rugged, facilitates accurate positioning of the insert on the tool holder, encourages reliable breaking of cutting chips, and enables internal threading in a small diameter hole. One insert includes four arms (34-40, FIG. 3) radiating from a mount portion (24), with each arm having a radially outer edge (52) and a pair of opposite sides (54, 56), and forming a cutting edge (58, 60) at the interception of each side with an end of the outer edge. The mount portion has four flat locating surfaces (42-48) lying at the sides of an imaginary square, with each locating surface lying between a pair of arms and with there being an obtuse angle (D) between each locating surface and an adjacent side of an arm.