A biopsy device comprises a body, a needle, and a cutter actuation mechanism. The needle extends distally from the body. The cutter actuation mechanism rotates and translates the cutter relative to the body and relative to the needle. The cutter has an overmold presenting a lead screw and a hex portion. The cutter actuation mechanism comprises a first gear disposed about the hex portion of the overmold and a second gear engaged with the lead screw of the overmold by a nut that is integral with the second gear. The cutter actuation mechanism is operable to simultaneously rotate the first gear relative to the body at a first rotational speed and the second gear relative to the body at a second rotational speed. With the lead screw and the nut rotating at different rotational speeds, the lead screw rotates relative to the nut at a third rotational speed.