Abstract: A truss fabrication system for fabricating trusses includes a table, a gantry press and an obstruction detection device. A top of the table receives truss components arranged with at least some connector plates engaging at least some of the truss members. The gantry press includes a gantry mounted for movement along a path relative to the table for pressing the connectors into the truss components for joining the truss members together. An obstruction detection device is mounted on the gantry for detecting obstructions in the path of the gantry. The detection device defines a vertical detection plane located a predetermined distance from the gantry and is adapted to detect the presence of all obstructions entering the plane at substantially the same time for stopping movement of the gantry.