Cylindrical head boring tool, in particular a forstner bit

A cylindrical drill bit comprising:

• a shank and a cylinder, both being centered to a longitudinal rotational axis,
• said cylinder being arranged at one end of the shank and comprising
• at least two radial main cutting edges, radially extending from the longitudinal rotational axis, and defining a bit working rotational direction,
• a peripheral wall
• forming said cylinder,
• connecting radial ends of said at least two radial main cutting edges and chip space openings of a previous main cutting edge,
• and comprising at least two sets of circumferential cutting edges positioned at a circumference centered to the longitudinal axis,
• each set of circumferential cutting edges
• being arranged between two subsequent main cutting edges and
• comprising at least two circumferential cutting edges having mutually different radial distances from the rotational axis,
• wherein said mutually different radial distances of said circumferential cutting edges are defined by setting an inner surface angled at a circumferential cutting edge inner angle on said peripheral wall and an outer surface angled at a circumferential cutting edge outer angle on said peripheral wall, the inner surface and the outer surface being angled with respect to a line parallel to the rotational axis,
• wherein the inner surface defines an inner width and the outer surface defines an outer width,
• wherein the inner width and the outer width together make up a circumferential-cutting-edge width of the circumferential cutting edge, and
• wherein the inner surface and the outer surface join each other to form a top cutting edge.