A system for joining together pieces of cardboard is well-suited for use by children as a toy, or for more useful purposes such as joining cardboard to make useful structures such as furniture. The system includes various fasteners, connectors and supports that can be used to join pieces of cardboard without the need for tools such as drills, screwdrivers, wrenches, hammers, or the like. The system permits great flexibility in joining cardboard together such that it might be used to create sculptures or whimsical structures of a user's imagination, recreational structures like play forts or play houses, or more useful items like furniture.

A wood screw includes a shank, a head connected thereto, a drilling portion opposite to the head, a plurality of threads spirally disposed on the shank and the drilling portion, and at least two first ribs extending on the drilling portion between two adjacent thread convolutions of the threads. The first ribs extend in a direction different from a screwing direction. Each first rib has two first surfaces protruding from the shank and converging at a first edge. The first edges of the first ribs are orientated in the screwing direction. Accordingly, the first ribs assist the drilling portion in enlarging a cutting area to increase the cutting effect and reduce the screwing resistance derived from the screwing operation. The first ribs and the thread convolution cooperate to form three cutting points in cross section, thereby achieving a stable, speedy and effort-saving screwing effect.

A screw includes a shank, a head connected thereto, a drilling portion opposite to the head, a first threaded section spirally formed on the shank, and a leading threaded section spirally extending upwards from the drilling portion. The two threaded section are disconnected so that a valley is formed between them. At least one cutting unit protrudes from the valley and has two ends connected to the first threaded section and the leading threaded section respectively. The leading threaded section assists the drilling portion in cutting and drilling into an object while screwing, and the cutting unit protruding from the valley severs fibers which are not cut by the leading threaded section completely to prevent the entanglement of the fibers. The valley helps accommodate and evacuate cut chips. Therefore, the drilling resistance is reduced effectively to increase the screwing efficiency.

A multi-thread screw includes a head end, a shank and a tapered end. Both a high thread and a low thread begin on the tapered end and extend onto the shank. The tapered end of the thread may include a polygonal cross-sectional shape.

A screw fastener particularly adapted to improve retention while minimizing mushrooming in fibrous workpieces. A single-threaded lower portion neighbours the pointed tip of the screw and a dual-threaded upper portion neighbours the screw head. The upper portion has a first upper thread that spirals in an opposite direction to the singular lower thread, and a second upper thread that spirals in a same direction as the singular lower thread. The lower thread includes a plurality of thread turns that share a same major thread diameter while axially spanning multiple areas of the lower portion of the shaft that vary in diameter, including a bulged area, a reduced upper area of lesser shaft diameter than the bulged area at a location between the bulged area and the head, and a downwardly tapered lower area at which the diameter of the shaft narrows from the bulged area toward the pointed tip.

A speedy-screwing screw includes a shank, a head connected thereto, a drilling portion opposite to the head, a plurality of main threads and auxiliary threads disposed on the shank and extending in opposite directions. Each auxiliary thread has a plurality of cutting sections, each of which has two flank surfaces converging at a crest. Adjacent flank surfaces are continuously connected in reverse curves so that the crests are connected to be a wavy arrangement. During a screwing operation, the main threads execute a main cutting action, and concurrently the auxiliary threads push and then sever wood fibers effectively, thereby providing a dual cutting effect to prevent the shank and the drilling portion from being entangled in the wood fibers, reduce the screwing resistance caused by the entanglement of wood fibers, and speeding up the screwing operation.

System for mounting facade panels, comprising a centring sleeve with a collar and a base and a fastening element with a head, a shaft and a drill bit, wherein the base of the centring sleeve is connected to the rest of the centring sleeve by means of at least one predetermined breaking point and wherein the base comprises an opening in which the shaft of the fastening element is arranged during mounting and wherein the shaft of the fastening element comprises a projection which causes a release of the base at the predetermined breaking point when the fastening element is in a predetermined position relative to the base of the centring sleeve as well as a corresponding mounting method.

A self-drilling, anti-burr, threaded fastener is provided having at least two different thread portions. The first thread portion extends along the tip and the second thread portion extends along the tapered portion adjacent to the tip. A third thread portion can be provided between the first and second thread portions that includes a plurality of axial gaps that extend to the thread root to remove burrs. Alternatively, knurling is provided in an area where the first and second thread portions meet, and the knurling acts to remove burrs.

An anchor assembly for use with hollow panels, comprises a holding member, such as a hook, and an anchor. The anchor is adapted to penetrate a hollow panel, such as a wall, and, once the anchor assembly has been installed to the wall, the anchor is firmly secured thereto while the hook, which is joined to the anchor, is located on a visible side of the wall. The anchor includes a first anchor portion and a second vice portion. The anchor portion, when the anchor assembly is installed to the wall, extends through the hole defined in the wall while the vice portion is located behind the wall. An elbow portion is provided on the anchor between the anchor and vice portions for allowing the anchor to be pivoted when being installed in the wall from a first position where the vice portion is inserted though the wall to form the hole therein and a second position where the vice portion extends behind the wall and in abutment therewith and the anchor portion is lodged in the hole.

A sheet metal screw includes one or more of a tapered self-drilling tip, an asymmetric thread angle and/or a trilobular thread edge profile.