To make it possible for bores (16) that are in line with one another to be efficiently worked by means of a boring bar (2), the boring bar has a main body (10) with an axis of rotation (R) and a number of cutting elements (12, 12A) at intervals from one another in the axial direction (4) and also guiding elements (14) for guiding the main body (10) in a guiding bore (16A). The guiding elements (14) are kept at a distance from the axis of rotation (R) equivalent to a guide radius (r1). The main body (10) is divided into a functional region (19) and an eccentric region (10), wherein the cutting elements (12, 12A) and the guiding elements (14) are arranged such that they are distributed around the main body (10) over an angular range (a) of less than 180°. Furthermore, the circumferential side (22) of the main body (10) can be passed eccentrically through a respective bore (16, 16A) of which the unworked tube radius (r2) is less than the guide radius (r1).

A method for enlarging each one of an initial pair of holes, which includes a first hole, extending through a first component, and a second hole, extending through a second component, includes inserting a pilot member, corresponding to a tolerance of misalignment of the first hole and the second hole of the initial pair of holes, such that pilot member passes through a clearance gap, defined by at least a portion of a boundary of first hole and at least a portion of a boundary of second hole with pilot member having a first central axis. The method also includes cutting a second pair of aligned holes through first and second components, respectively, with a cutter section, which has a second central axis.

A cutter assembly for increasing a diameter of an initial pair of holes that includes a first hole defined through a first component and a second hole defined through a second component. The cutter assembly includes a pilot member having a pilot diameter corresponding to a tolerance of misalignment of the first hole and the second hole. Further included is a cutter section associated with the pilot member wherein the cutter section has a cutting diameter larger than the pilot diameter and the cutter section is configured to produce a second pair of aligned holes in the first and second components having a diameter dimension of that of the cutting diameter.

A rotation tool is mounted to a spindle of a machine tool. The rotation tool comprises a cutter holding portion to which blade portion is fixed and a fixing device which fixes a workpiece. The blade portion is disposed at a tip end of the cutter holding portion. The fixing device includes a movement portion formed to be movable in the interior of the cutter holding portion and a pressing device which presses the movement portion to a side toward the workpiece. The fixing device includes a shaft portion rotatably supported relative to the movement portion and a pressing portion which presses the workpiece.

A hole saw alignment guide for enlarging a hole in an object to provide a larger diameter hole in the object. The hole saw guide includes a first cylindrical part having a first end adapted to the size of, and adapted to be inserted into, the hole that is to be enlarged. The hole saw guide also has a second cylindrical part integral with the second end of the first cylindrical part. The hole saw guide is adapted to receive over the outer surface of the first cylindrical part a toothed end of a hole saw sized to provide the larger diameter hole. The second cylindrical part is adapted to extend into an arbor of the hole saw and to be secured to the arbor for rotation with the hole saw. The arbor of the hole saw is adapted to be received in a drill chuck.

A rotation tool is mounted to a spindle of a machine tool. The rotation tool comprises a cutter holding portion to which blade portion is fixed and a fixing device which fixes a workpiece. The blade portion is disposed at a tip end of the cutter holding portion. The fixing device includes a movement portion formed to be movable in the interior of the cutter holding portion and a pressing device which presses the movement portion to a side toward the workpiece. The fixing device includes a shaft portion rotatably supported relative to the movement portion and a pressing portion which presses the workpiece.