A more improved screw for fastening different materials is provided. The screw for fastening different materials is configured such that a cross-sectional shape of a sharp head part includes three vertexes, lines connecting the respective vertexes each have a curved shape projecting outward, and ridge parts, and formed by connecting vertexes of the sharp head part are helical toward the tip end along the same direction as a helical direction of a screw thread of a main screw part.

A multipurpose screw is provided. The screw comprises: a head having a tool engaging formation, a self-drilling drill tip, and a shank extending between the head and the drill tip. The shank includes a threaded portion and an unthreaded portion. The threaded portion includes a major thread extending from the drill tip. The ratio between the major diameter of the major thread and the pitch of the major thread is from 1.2 to 2.4.

A low resistance anti-crack screw structure, including a low resistance screw comprising an upper section of screw, a middle section of screw, a lower section of screw, and a cone-shaped screw tail. The lower section of screw is recessed with at least one chip ditch that gradually becomes deeper from top to bottom. The chip ditch is tilted with respect to the central axis of the low resistance screw and has a chip removal angle between 10 degrees and 20 degrees. The second ditch section is inclined relative to the radial direction having an incline angle between 79 degrees and 89 degrees, and the maximum depth of the second ditch section is less than 55% of the radius of the lower section of screw. The lower side of the chip ditch is tapered close to the screw tail and has a drag reduction angle between 15 degrees and 20 degrees.

A floating connection fastening system employs a semi-flexible floating bushing having a sleeve with an axial slot which captures a fastener having a head, an unthreaded shank portion, a threaded portion and an intermediate reamer. An adapter mounts to the bushing/fastener assembly and receives a driver bit. The adapter defines an offset clearance. The floating connection is installed by driving the fastener through a non-load bearing member so as to form a bore and embed the fastener into a load bearing member. The floating bushing has a flange which engages the surface of the non-load bearing member. The installation may be performed in essentially a one-step procedure.