A surgical instrument includes a body, a shaft assembly, and an end effector. The end effector includes an ultrasonic blade and a clamp arm movably coupled with the shaft assembly. The shaft assembly extends between the body and the end effector and includes an acoustic waveguide, a rotational driver, and a driver wrench. The rotational driver is configured to be received within the rotational drive channel and rotate the shaft assembly relative to the body. The acoustic waveguide includes a notch and the driver wrench includes a key, wherein the first notch of the acoustic waveguide is configured to receive the key.