A surgical instrument comprises a hand-held portion configured to be manipulated by a user and a pivoting portion operatively coupled to the hand-held portion. The pivoting portion is configured to pivot with respect to the hand-held portion according to first and second degrees of freedom. The pivoting portion includes an accessory drive motor, an accessory drive member configured to be driven by the accessory drive motor, a plurality of lead screws, a carriage including a central aperture axially extending through the carriage and configured to interface with and linearly translate along the plurality of lead screws, and a linear drive motor configured to rotate the plurality of lead screws to linearly translate the carriage relative to the hand-held portion with respect to a third degree of freedom. The accessory drive member extends through and is configured to move within the central aperture of the carriage.