Abstract: A cylindrical head boring tool (1), such as a Forstner drilling tool, with a main cutting edge (4) having a centering point (5). The main cutting edge extends diametrically across the entire circular cross-section of the boring head (3), the main cutting edge (4) having cut out surfaces (11), and chip channels (7) adjacent the main cutting edge (4). The chip channels (7) open through the outer periphery and extending obliquely through the boring head (3). Each end of the main cutting edge (4) is adjacent a preliminary cutting edge (8) coinciding with the circumference of the boring head (3) for guiding the boring tool (1). The preliminary cutting edge (8) reaches to the edge of the respective other chip channel (7) and forms the peripheral edge of an essentially cylindrically curved wall (6) of the boring head (3). The otherwise smooth wall (6) is interrupted by radial throats (13).

Abstract: A cylindrical bit including a drill head with a centering tip, two circumferential cutters, two main cutting edges extending approximately radialy, and two chip channels associated with main cutting edges. The chip channels are open toward a circumferential surface and toward a rear of the cylindrical bit. To improve chip removal, each chip channel bottom surface is rounded in a curved fashion and blends continuously with the respective chip surfaces of the corresponding main cutting edges and with chip channel side walls opposite the respective chip surfaces.