A surgical instrument (10, 200), comprising: (a) an end effector, comprising: (i) an ultrasonic blade, and (ii) a clamp arm (44, 112) configured to move relative to the ultrasonic blade between an open position and a closed position; (b) an articulation section located proximally relative to the end effector, wherein the articulation section is configured to deflect the end effector between a non-articulated configuration and an articulated configuration; (c) an acoustic waveguide comprising a distal portion coupled to the ultrasonic blade, wherein the distal portion extends along an axis; (d) a clamp arm closure assembly comprising a body extending distally from the articulation section, wherein the body is configured to actuate in order to drive the clamp arm between the open position and the closed position; and (e) a clamp arm clocking assembly (180, 280) configured to drive rotation of the clamp arm about the axis relative to the ultrasonic blade between a first clocked position and a second clocked position, the clamp arm clocking assembly comprising: (i) a rotating body (150, 250) configured to rotate relative to the ultrasonic blade about the axis, wherein the clamp arm is pivotally coupled to the rotating body, (ii) a translating driver (182, 282, 340) extending through the articulation section, and (iii) a rotation driver assembly (163, 281) in communication with the translating driver and the rotating body, wherein the rotation driver assembly is configured to convert translational motion of the translating driver into rotational motion of the rotating body to drive the clamp arm between the first clocked position and the second clocked position, characterised in that the rotating body (150, 250) comprises an annular array of proximally presented gear teeth (158, 258) wherein the rotation driver assembly (163, 281, 301, 311, 321, 331, 351, 371) comprises a first gear (194, 288, 309, 319, 329, 339, 359) that meshes with the annular array of proximally presented gear teeth (158, 258) of the rotating body (150, 250). (a) an end effector, comprising: (i) an ultrasonic blade, and (ii) a clamp arm (44, 112) configured to move relative to the ultrasonic blade between an open position and a closed position; (i) an ultrasonic blade, and (ii) a clamp arm (44, 112) configured to move relative to the ultrasonic blade between an open position and a closed position; (b) an articulation section located proximally relative to the end effector, wherein the articulation section is configured to deflect the end effector between a non-articulated configuration and an articulated configuration; (c) an acoustic waveguide comprising a distal portion coupled to the ultrasonic blade, wherein the distal portion extends along an axis; (d) a clamp arm closure assembly comprising a body extending distally from the articulation section, wherein the body is configured to actuate in order to drive the clamp arm between the open position and the closed position; and (e) a clamp arm clocking assembly (180, 280) configured to drive rotation of the clamp arm about the axis relative to the ultrasonic blade between a first clocked position and a second clocked position, the clamp arm clocking assembly comprising: (i) a rotating body (150, 250) configured to rotate relative to the ultrasonic blade about the axis, wherein the clamp arm is pivotally coupled to the rotating body, (ii) a translating driver (182, 282, 340) extending through the articulation section, and (iii) a rotation driver assembly (163, 281) in communication with the translating driver and the rotating body, wherein the rotation driver assembly is configured to convert translational motion of the translating driver into rotational motion of the rotating body to drive the clamp arm between the first clocked position and the second clocked position, characterised in that the rotating body (150, 250) comprises an annular array of proximally presented gear teeth (158, 258) (i) a rotating body (150, 250) configured to rotate relative to the ultrasonic blade about the axis, wherein the clamp arm is pivotally coupled to the rotating body, (ii) a translating driver (182, 282, 340) extending through the articulation section, and (iii) a rotation driver assembly (163, 281) in communication with the translating driver and the rotating body, wherein the rotation driver assembly is configured to convert translational motion of the translating driver into rotational motion of the rotating body to drive