A screwdriver is disclosed comprising a base, a carriage moveably coupled
to the base, an actuator operable to move the carriage relative to the
base, and a slider comprising an attached screw bit, wherein the slider
is coupled to the base through the carriage and the slider is moveably
coupled to the carriage such that the slider and attached screw bit move
together relative to the carriage. The screwdriver further comprises a
position detector operable to detect a position of the slider relative to
the carriage. In one embodiment, the carriage is moved relative to the
base to move the screw towards the work surface. After the screw contacts
the work surface, the carriage is moved further relative to the base
causing the slider to move relative to the carriage, and the movement of
the slider relative to the carriage is detected using the position
detector.