Tool for roughening a borehole surface

A tool for roughening a borehole surface, the tool comprising:

• a coupling portion for clamping the tool in a drilling machine;
• a tool head for machining the borehole surface;
• and
• an extraction duct, wherein the coupling portion is disposed at a first end of a tool shank and the tool head at an opposite, second end of the tool shank, and wherein the tool head comprises at least one cutter with solid radial extensions disposed on a circumferential surface of the tool head and arranged to cut in a direction pointing away from a longitudinal axis of the tool,
• wherein the tool head has at least one slit which discharges into the extraction duct, the at least one slit passing through from one side to another side of the tool head and, starting from an end face of the tool head, extends axially along the longitudinal axis of the tool,
• wherein the extraction duct extends at least partly axially along the longitudinal axis of the tool for extraction of drilling dust, and
• wherein the extraction duct, starting from the end face of the tool head, extends inside the tool shank and discharges circumferentially into a connecting opening in the tool shank.