Abstract: The present invention provides a screw/bolt thread profile geometry that is particularly suited to forming a mating nut thread when the screw is inserted in to a plain diameter hole, in the anchor and rotated in a manner by which the thread helix angle will cause the relative axial forward movement, of the screw/bolt, into the anchor. This rotation and relative axial movement will be the prime mover in developing the nut thread that has mating contact with the screw/bolt thread.

Abstract: A blank for a self tapping fastener, and corresponding fastener is provided. The blank defines an odd number of lobes along a cross section taken perpendicular to its axis of rotation. The lobes define a relatively high out-of-round cross section along a tapered thread-forming zone, and a relatively low out-of-round cross section along the main body taken in a direction toward the drive head. Between the main body and tapered thread-forming zone is located an additional thread forming zone having an axial length of approximately one thread pitch and a cross section that conforms to the high out-of-round of the tapered zone. The maximum diameter (at the lobes) of the additional thread-forming section approximately matches that of the full-diameter main body section. A lower-diameter stabilizing section can be provided ahead of the tapered zone, adjacent the tip of the fastener.