Abstract: A nut having a cutting and fastening structure thereof applied to fasten at least a board with a hole are disclosed. The nut has at least a cutting through itself. The fastening structure includes a bolt and a nut. When the nut is threaded on the bolt, the cutting of the nut and threads of the bolt touch each other for increasing the friction.

Abstract: An anti-backlash mechanism is described in the form of a pair of nuts or nut halves with internal threads complementary to the threads on a lead screw. The mechanism is traslated by rotation of the screw. One of the nuts has an outer cantilevered wall with inner gear teeth which engage outer gear teeth on the other nut. Rotation of one nut with respect to the other nut tightens or loosens an abutting frictional rotation-opposing resistance of an elastomeric washer compressed between the two nuts. The compressed washer exerts a bias force against the nuts opposing axial forces exerted by the lead screw against the flanks of the nut threads.

Abstract: In order to provide a lock nut having a high reliability free from loosening, three nuts are used. The nut closest to the bolt head and the intermediate nut are engaged with each other in only the peripheral direction and do not come into surface-contact with each other in the axial direction, thereby aligning the outer peripheries thereof and forming internal threads on a variety of center bores. Then, the intermediate nut and the outermost nut are brought into press-contact with each other in the axial direction.