One embodiment relates to a handheld surgical instrument that comprises a rotary surgical end effector and a coupler configured to cause rotation of the same. The handheld surgical instrument further comprises a motor, which is configured to drive a motor output region. The handheld surgical instrument further comprises a transmission, which defines a transmission input region that interfaces with the motor output region and a transmission output region coupled to the transmission input region. The transmission output region is operably coupled to the coupler, and the transmission is configured to alter the speed of the coupler relative to the motor output region. The motor output region and the transmission input region interface one another at a motor-transmission interface, and the motor-transmission interface comprises a motor-transmission backlash such that drive of the motor output region within the motor-transmission backlash does not cause rotation of the rotary surgical end effector.