The invention relates to a blade attachment assembly for mower blades driven in an oscillating manner having a shaft (1) which defines a first longitudinal axis (X) and has a receiving space (4) a mower blade drive pin engaging in the receiving space (4) and detachably connected to the shaft (1) which extends axially with respect to the first longitudinal axis (X ) beyond the shaft (1) and defines a second longitudinal axis (Y) that is offset radially with respect to the first longitudinal axis (X) wherein a wall (5) of the shaft (1) that delimits the receiving space (4) has a first supporting face (6) curved in the circumferential direction and wherein a top bearing holding area (13) of the mower blade drive pin (2) that engages in the receiving space (4) has a curved first contact face (14) that is in contact with the supporting face (6) and corresponds to the first supporting face (6) and connecting means (24) for the detachable connection of the mower blade drive pin (2) to the shaft (1) characterized in that an undercut (8) is formed in the wall (5) delimiting the receiving space (4) and in that the top bearing holding area (13) of the mower blades drive pin (2) has a collar (16) engaging in the undercut (8) wherein the undercut is formed as a groove (8) in the wall (5) that extends radially with respect to the second longitudinal axis (Y).
