Abstract: A method for manufacturing thread-forming screws wherein the tapered leading end of the screws can include thread portions or sections having sharp crests but wherein the thread-forming screws can be made using conventional flat thread rolling dies. Also provided is a screw blank having a tapered leading end particularly shaped or formed such that when the threads are rolled on the screw blank using conventional flat thread rolling dies, the tapered leading end of the screw will include thread sections having sharp crests.

Abstract: A modified Phillips-type cruciform recess in a screw or the like, which provides a cling-fit with a driver by causing deflection of the flutes of the driver against the walls of the slot in the recess, comprises a central socket portion and radially extending slots adapted to receive the flutes of a suitable driving tool. Each slot is defined in part by a bottom surface of substantially uniform width which slopes radially inwardly and downwardly along the axis of the screw. The bottom surface joins two opposing surfaces which form the walls of the slot. The pairs of opposite slots in the cruciform pattern are not symmetrically located relative to a plane including the longitudinal axis of the screw, but are offset laterally in opposite directions with respect to such a plane. On insertion of a standard driver into the recess, the flutes of the driver are caused to flex into frictional engagement with the walls of the slots, thereby achieving the desired cling-fit.

Abstract: An improved concrete anchor consists of an expansion nut in the form of a cylindrical coil of a resilient material and a bolt provided with a thread adapted to receive the coil. The thread of the bolt has two sections of different effective minor diameters. A first section immediately adjacent the threaded end of the bolt has a minor diameter sufficiently small to permit the bolt to enter the coil without causing any distortion or enlargement in the outer diameter of the coil. Adjacent the first threaded section and extending toward the head of the bolt is a second section having a larger minor diameter which causes expansion of the coil on engagement therewith. The end of the coil facing away from the head of the bolt is provided with a short, straight tab portion which extends in a direction generally away from the head of the bolt while tapering inwardly toward the axis thereof.

Abstract: A screw head recess includes a generally frusto-conical central socket and radial slots interconnected by concave sections of the socket. Each slot is defined by two opposed wall surfaces which intersect with a bottom surface which slopes radially inwardly and downwardly along the axis of the screw. At least a portion of the junction between one sidewall and the bottom surface is curved to produce a camming surface for frictional engagement between the screw and a driving tool sufficient to provide a temporary stick-fit between the screw and the tool.

Abstract: A threaded fastener incorporates a long-pitch helical thread rolled on a cylindrical blank of predetermined diameter, leaving untouched a section of the blank between adjacent turns or convolutions of the thread. The thread has a crest which is greater in diameter than the blank and a root which is smaller in diameter than the blank. The contour of the thread in a plane including the longitudinal axis of the screw is unsymmetrical about a line perpendicular to the axis and passing through the crest, the flank of the crest facing the head end of the screw being more nearly perpendicular to the axis than the flank facing the work-entering end of the screw. At each juncture between the root of the thread and the adjacent untouched blank sections, there is an outwardly extending helical bur or crest which functions as an auxiliary thread to improve the holding power of the screw.

Abstract: An improved thread-forming screw has a circular threaded main body portion and a tapered lobular pilot or thread-forming section comprising a plurality of transverse elongated projections or lobes on a circular conical core, each lobe having a sharp ridge running the full length thereof. The sharp edges on the lobes minimize the torque required to form threads in a workpiece, while the circular main body portion maximizes the holding power of the screw in the workpiece.

Abstract: A tilting terminal clamp assembly wherein the clamping plate associated with the threaded shank is generally circular and is equipped with serrations about the periphery for engagement with the sidewalls of a terminal body pocket, the clamping plate being chamfered about its central aperture to provide a four-point contact when engaging a wire in the pocket, the plate also being equipped with radially extending ribs outstanding from an annular groove to bightingly engage the wire.