Abstract: A corrosion-resistant cap for use with a fastener and an elastomeric washer. The cap has a hollow head forming a cavity into which the head of the washer is placed, a perimeter outer skirt, and an inner skirt which can be swaged or bent from a longitudinal position to a transverse position perpendicular to the axis of the fastener to make contact and cover the lower surface of the flange of the fastener. This completely encloses the flange and head of the fastener and forms a cavity defined by the outside surface of the inner skirt and the inside surface of the outer skirt. An elastomeric washer will then be threaded onto the threaded shank of the fastener so that it is positioned and held in place by the cavity. Thus, when the fastener and cap are tightened down onto an object, the elastomeric material of the washer flows, completely filling the cavity and the area between the bottom of the outer skirt and the object to which the fastener is attached.

Abstract: A planar stress plate-buttress thread fastener assembly in which the stress plate's annulus has teeth formed on the perimeter thereof and pointed in the direction of the installation rotation of the fastener. The teeth are deflected downward out of the plane of the plate such that when the fastener is counterrotated the teeth will penetrate the fastener and prevent backout.

Abstract: A bi-metallic screw fastener blank for a self drilling screw of a given root diameter is disclosed. The screw blank comprises a metallic head and shank member made of a first material that is welded to a metallic slug member that is of equal diameter to the head and shank member but is made of a second material which is heat hardenable. The blank is characterized by an annular groove at the weld interface between the head and shank member and the slug member that has a diameter equal to the given root diameter of the screw.

Abstract: A drill screw having primary and secondary cutting edges on opposite sides of its longitudinal axis, with the primary cutting edge offset so that it contacts the work-piece first, at a position displaced laterally from the screw axis, and produces initial very rapid drilling of an opening through the work-piece, followed by a period of drilling by both cutting edges. A conical portion is also preferably provided on the screw which extends divergingly from the cutting edges toward the head end of the screw until its diameter matches the root diameter of the screw.

Abstract: A screw for use in fastening resilient insulation to a metal building surface having threads near its tip and a reduced-diameter portion just above the threads, so that when the threaded portion has been screwed entirely through an opening in the substrate, the reduced-diameter portion of the screw is free to reciprocate in the opening and then permit compression and reexpansion of the insulation while still retaining it against lift-off.