A fastener includes a head with a top face and a conical bottom face, and a shank with a threaded portion spiraling thereon and a drilling portion. The head includes a plurality of cutting portions and cutting ribs formed on the bottom face to thereby cut and shave fibers and accommodate chips. Each cutting portion extends towards the shank and includes a projecting blade formed circumferentially of the top face, and an adjoining wall and a flank wall respectively connected to the projecting blade and meeting at a cutting edge. The cutting ribs extend radially relative to the shank. The cutting portions and the cutting ribs cooperate to continue cutting and press remnants and the bulge down so that the head fits flush with the surface of the workpiece to thereby increase the evenness and the fastening effect after the head is fastened in position.

A screw capable of cutting and compressing dregs in an object to be drilled has a tapered head with a larger upper end and a small lower end, and a tapered surface being formed between the larger upper end and the small lower end; and at least one rib winding around the tapered surface of the head. Each of the rib is formed by an outer wall and an inner wall the connection of the inner wall and outer wall is formed as a sharp knife portion which winds around the tapered surface of the tapered head; and the outer wall is inclined so that a lower distal side of the outer wall is more near a center axis of the tapered head; and the inner wall is inclined so that an upper distal end of the inner wall is more near a center axis of the tapered head.

A self-drilling screw, particularly for use in a security screen employing leveraged clamping. The self-drilling screw comprises a head and a shank. A drill bit is formed at one end of the shank away from the head with a thread extending along the full length of the shank, including the drill bit. The thread on the drill bit increases holding strength.

A cement board screw a high thread that begins on the tapered end, extends onto the shank and terminates at a first axial location along the shank. The high thread defines a high peripheral edge, where a leading flank and a trailing flank meet at the high peripheral edge and together define a high thread angle that is between about thirty degrees and about fifty-five degrees. A low thread begins on the tapered end, extends onto the shank and terminates substantially at the first axial location along the shank such that an axial length of the low thread is substantially the same as and contiguous with an axial length of the high thread. The low thread includes a leading flank and a trailing flank that meet at a low peripheral edge and together define a low thread angle that is between about fifty degrees and about seventy degrees.

A fastener includes a shank having a point at a first end and a second, head end. A head structure at the head end includes a top portion and having a cutting structure, the cutting structure comprising four planar walls, each wall engaging the shank at an angle, each wall adjoining an adjacent wall by a rounded edge.

A self-tapping screw head structure includes a screw head, a rod, a cone and a thread. A direction of the thread surrounding the cone and the rod determines a tapping direction. The screw head includes a top portion, a first neck portion connected to the top portion and having a circumference decreasing towards away from the top portion, a plurality of recesses recessed at a surface of the first neck portion, and a second neck portion connected to the first neck portion and having a circumference gradually decreasing towards away from the first neck portion. Each of the plurality of recesses includes a cutting end, a crumb guiding end away from the cutting end, a first accommodating groove and a second accommodating groove. A recess depth of the first accommodating groove is greater than that of the second accommodating groove.

A low energy wood screw that may be inserted quickly and using less energy than conventional screws. In various embodiments, the screw may include a countersunk head having a recess for accommodating a driving tool, a tapered neck, a plurality of crown ribs extending over the head and neck, a lubricating coating, main threads with a large thread lead, and lower threads having an asymmetrical profile and extending onto a gimlet point.

A facial alignment system that includes a first mask portion and a rear portion. The rear portion includes a tightening mechanism mounted thereon that includes first and second tightening members that extend from the rear portion to the mask portion. The first and second tightening members are configured to exert a tightening force on the first mask portion.

A screw includes at least one helical thread with a peripheral edge having notched regions spaced apart by notch-free regions. An underside of a head of the screw includes projecting nibs.