The tool exhibits a first tool part (2) and a second tool part (3), which possess a common axis of rotation (A). The first tool part (2) is provided with an alignment pin (4) and exhibits at its root an annular surface (5). The second tool part (3) possesses an axial bore (7) to receive the alignment pin (4) and an annular surface (6), which is capable of being tensioned against the annular surface (5) of the first tool part (2). Tensioning structures (8, 9, 10) serve for the axial tensioning of the two tool parts (2, 3) to one another. The tensioning structures (8, 9, 10) exhibit three retaining screws (8, 9, 10) arranged distributed around the periphery of the second tool part (3), which retaining screws are each screwed radially into a threaded bore (12, 13, 14) of the second tool part (3) and each engage in a radial bore (21, 22, 23) of the alignment pin (4). A recess (16, 17, 18) is allocated to each bore (21, 22, 23), so that the alignment pin (4) is caused to become polygonal at its periphery by tensioning the retaining screws (8, 9, 10) of the alignment pin (4). Higher stability and vibration damping can be achieved because of the polygonal bulging of the alignment pin (4). The tool is further characterized by its high compatibility and ease of operation.