Patent ID: 8499431

Claim:
A clamping apparatus for coupling a tool member to an output shaft of a power tool, the clamping apparatus comprising: a clamp member coupled to an output shaft; a piezoelectric element opposing the clamp member, the piezoelectric element configured to change from a first state to a second state in response to being coupled to a source of electrical energy; and a controller electrically coupled to the piezoelectric element, the controller including an actuator movable between a first position and a second position, wherein in response to the actuator moving from the first position to the second position the controller (i) couples the piezoelectric element to the source of electrical energy and (ii) energizes a source of rotation to rotate the output shaft after a first predetermined time period, and in response to the actuator moving from the second position to the first position the controller (i) deenergizes the source of rotation and (ii) decouples the piezoelectric element from the source of electrical energy after a second predetermined time period.