Abstract: A screw fastener for use in a masonry element having a pilot hole of predetermined length and diameter, the screw fastener including a shank having a diameter less than the diameter of the pilot hole, and having a tip at one end and a head at the other end; a set of helical threads extending from the tip over a portion of the length of the shank, wherein the threads have a pitch at least as great as the diameter of the shank; and a set of one or more helical grooves of the opposite rotational hand to the threads, which grooves extend through the threads and into the shank, wherein the pitch of the grooves is in the range of two to twenty times the diameter of the shank.

Abstract: An integrally formed screw, such as a wood screw has a threaded cylindric stem and a head (9). At least a part (25) of the head (9) is shallowly convexly curved (25) and is provided with a screwdriver recess (26). The head (9) has an annular, shallowly concave underside (22) adapted to accommodate a relatively soft, polymeric washer (27).

Abstract: An integrally formed screw, such as a wood screw has a threaded cylindric stem and a head (9). At least a part (25) of the head (9) is shallowly convexly curved (25) and is provided with a screwdriver recess (26). The head (9) has an annular, shallowly concave underside (22) adapted to accommodate a relatively soft, polymeric washer (27).

Abstract: The thread (15) of a wood or the like screw has pairs of V-shaped recesses (22, 23) in the edge of a selected intermediate length of the thread (17). Each pair defines a W-shaped cutout (19, 20, 11). The cutouts (19-21) extend into only a part of radial width of the thread (15). There are only about five cutouts (19-21) at each convolute (17) of the limited length. The lengths of the thread portion (16) at the tip and the thread portion (18) at the head (13) of the screw are devoid of the cutouts. Each cutout defines a cutting tooth (24) which facilitates the driving of the screw into the workpiece. The recesses (22, 23) provide cavities for fibrous debris generated by the respective tooth (24). When the screw is in place, the teeth (24) are pressed axially toward the thread produced in the workpiece to reduce the loosening tendency of the installed screw. The disposition and size of the cutouts (19-21), is about three cutouts per one convolute so as not to unduly impede the torque strength of the screw.

Abstract: A screw, particularly a wood screw present a combination of a threaded cylindric stem (10) merging, over an inversely frustoconical part (16) with an enlarged diameter cylindric portion (20) which is integral with an underside of a large diameter washer section (23) which, in turn is integral with a shallowly convex head portion (25). The invention is intended for wood screws usually in the range of about 6 mm and provides a reduced chance of injury by providing a smooth merging with the flat surface on which the screw head is located. Also, the screw has an improved torque characteristics making it suitable for use with power screw driving tools.

Abstract: A self-countersinking screw including an inverted-conical head portion formed at a top with a cavity adapted to receive a tip of a screwdriver and having a conical bottom, said conical bottom having a plurality of triangular recesses each having a lateral side extending inwardly to form a sharp edge and a space for receiving chips, a threaded portion, and a tapered portion having a large diameter connected with the head portion and a small diameter connected with the threaded portion, whereby the sharp edge will make a countersink on a workpiece when the countersunk head screw is turned therein.

Abstract: A self-countersinking screw including an inverted-conical head portion formed at a top with a cavity adapted to receive a tip of a screwdriver and having a conical bottom, said conical bottom having a plurality of triangular recesses each having a lateral side extending inwardly to form a sharp edge and a space for receiving chips, a threaded portion, and a tapered portion having a large diameter connected with the head portion and a small diameter connected with the threaded portion, whereby the sharp edge will make a countersink on a workpiece when the countersunk head screw is turned therein.