A rotating chuck comprising: a front chuck end ; and a shank-receiving bore opening out to, and extending rearwardly from, the front chuck end ; the shank-receiving bore defined by a circumferentially extending bore surface and: having a bore axis (A B ) extending through the center of the shank-receiving bore and defining forward and rearward directions; and comprising a front bore end proximate to the front chuck end of the chuck and a rear bore end rearward of the front bore end ; the bore surface comprising: one or more shank abutment sub-surfaces defining a bore diameter (D B ); and a groove arrangement recessed in the shank-receiving bore further than the one or more shank abutment sub-surfaces from the central bore axis (A B ); the groove arrangement defining a flow path in fluid communication with the front and rear bore ends and comprising: an annular inlet groove at the rear bore end ; one or more slanted groove portions opening out to, and being inwardly inclined towards, the front chuck end ; and one or more intermediary grooves connecting the annular inlet groove and the one or more slanted groove portions , the one or more intermediary grooves opening out only inwardly into the bore surface or both to the bore surface and an external surface of the rotating chuck ; wherein the shank-receiving bore , including the groove arrangement , is formed on a portion of the rotating chuck having one-piece unitary construction; characterized in that the one or more intermediary grooves include one or more longitudinal groove portions extending parallel with the central bore axis (A B ). a front chuck end ; and a shank-receiving bore opening out to, and extending rearwardly from, the front chuck end ; the shank-receiving bore defined by a circumferentially extending bore surface and: having a bore axis (A B ) extending through the center of the shank-receiving bore and defining forward and rearward directions; and comprising a front bore end proximate to the front chuck end of the chuck and a rear bore end rearward of the front bore end ; having a bore axis (A B ) extending through the center of the shank-receiving bore and defining forward and rearward directions; and comprising a front bore end proximate to the front chuck end of the chuck and a rear bore end rearward of the front bore end ; the bore surface comprising: one or more shank abutment sub-surfaces defining a bore diameter (D B ); and a groove arrangement recessed in the shank-receiving bore further than the one or more shank abutment sub-surfaces from the central bore axis (A B ); the groove arrangement defining a flow path in fluid communication with the front and rear bore ends and comprising: an annular inlet groove at the rear bore end ; one or more slanted groove portions opening out to, and being inwardly inclined towards, the front chuck end ; and one or more intermediary grooves connecting the annular inlet groove and the one or more slanted groove portions , the one or more intermediary grooves opening out only inwardly into the bore surface or both to the bore surface and an external surface of the rotating chuck ; wherein an annular inlet groove at the rear bore end ; one or more slanted groove portions opening out to, and being inwardly inclined towards, the front chuck end ; and one or more intermediary grooves connecting the annular inlet groove and the one or more slanted groove portions , the one or more intermediary grooves opening out only inwardly into the bore surface or both to the bore surface and an external surface of the rotating chuck ; wherein the shank-receiving bore , including the groove arrangement , is formed on a portion of the rotating chuck having one-piece unitary construction; characterized in that the one or more intermediary grooves include one or more longitudinal groove portions extending parallel with the central bore axis (A B ). <EOS>