Rotatable assembly (10) having one end (12) adapted to be secured to a rotatable support for rotating the rotatable assembly (10) about a rotational axis (28), the rotatable assembly (10) comprising: a main body (18) having a cavity (56); a damping mass (38) arranged within the cavity (56) and movable in radial directions (30), substantially perpendicular to the rotational axis (28), relative to the main body (18); a damping structure (36) arranged to support the damping mass (38) relative to the main body (18) and arranged to damp vibrational movements of the damping mass (38) relative to the main body (18) in the radial directions (30); wherein the damping structure (36) comprises a plurality of spring elements (40); and wherein each spring element (40) has a flat appearance.

Rotatable assembly (10) having one end (12) adapted to be secured to a rotatable support for rotating the rotatable assembly (10) about a rotational axis (28), the rotatable assembly (10) comprising: a main body (18) having a cavity (56); a damping mass (38) arranged within the cavity (56) and movable in radial directions (30), substantially perpendicular to the rotational axis (28), relative to the main body (18); a damping structure (36) arranged to support the damping mass (38) relative to the main body (18) and arranged to damp vibrational movements of the damping mass (38) relative to the main body (18) in the radial directions (30); wherein the damping structure (36) comprises a plurality of spring elements (40); and wherein each spring element (40) has a flat appearance.

A rotary cutting tool includes a tool body including a shank portion and a cutting portion adjoining the shank portion. The cutting portion has a plurality of blades separated by helically twisted flutes. A tunable vibration absorber is disposed within an internal cavity formed in the cutting portion and has a shape that follows the helically twisted flutes. The tunable vibration absorber includes an absorber mass and a resilient material disposed between the absorber mass and an outer wall of the internal cavity. In one aspect, the tunable vibration absorber is tuned to a desired frequency by selecting the mechanical properties of the absorber mass and the resilient material. In another aspect, the tunable vibration absorber is tuned by controlling a pressure of fluid within a main internal fluid cavity disposed within the tunable vibration absorber.