A surgical tool assembly. The tool assembly includes a first jaw and a second jaw that is movably supported on the first jaw for selective movement relative to the first jaw between an open position and a closed position. The tool assembly further includes a shaft assembly that defines a shaft axis. The shaft assembly includes an axially movable closure member that is configured to apply an initial closure motion to a cam surface on the second jaw in a first closure direction that is normal to the cam surface and an additional closure motion to the cam surface in a second closure direction that is parallel to the shaft axis.
