A robotic surgical tool includes a drive housing having a lead screw extending from a first end of the drive housing, a carriage movably mounted to the lead screw at a carriage nut secured to the carriage, and an elongate shaft extending from the carriage and penetrating the first end, the shaft having an end effector arranged at a distal end thereof and comprising a proximal shaft portion releasably coupled to a distal shaft portion at a releasable interface. Proximal and distal portions of one or more mechanisms of the surgical tool extend from the carriage to the end effector within the proximal and distal shaft portions, respectively, and the one or more mechanisms are operable to operate or articulate the end effector.