Abstract: A boring head for drilling deep holes of large diameter has a cylindrical body provided with a transverse slot in which a rectangular insert holder is clamped. The insert holder has a plurality of indexable inserts mounted thereon and a semi-cylindrical stabilizer is attached at each end of the insert holder and is provided with wear strips to support the boring head in the workpiece. The stabilizer and insert holder form a "D" shaped cross section which creates an annular space for the discharge of chips and coolant. The insert holder is provided with pockets cut at preselected angles which determine the rake angle of the inserts.