Abstract: A tapping machine (10), for tapping perforated products such as nuts (14), bushings or the like, comprises a spindle (11) on the longitudinal axis (12) of which a tapping tool (13) is rotatably mounted which tapping tool (13) is provided with a stem (21) having a longitudinal axis and a head having a threading to be inserted inside an appropriate hole provided in a nut (14) to be threaded, as well as pusher devices (16) for pushing a nut (14) against the threading surface of the tapping tool (13). Said machine further comprises an anti-vibration centring group (19) which acts on the stem of the tapping tool (13), substantially constraining the tapping tool (13) in a radial direction, preventing a de-alignment of the longitudinal axis (12) of the stem of the tapping tool and maintaining freedom of rotation thereof. Said anti-vibration centring group (19) is selectively movable along the stem of the tapping tool (13) in a parallel direction to the longitudinal axis of said stem (21).

Abstract: A structural fixing system with high clamping force, tightening precision and high corrosion resistance, in particular for light and heavy metalwork elements, comprises a flanged metal bolt (10), and/or a flanged metal nut (20), obtained by hot or cold forming. In the space between the base of the flange (12) and the shank (13) of the bolt (10) or below the flange of the nut (20) is a precision collar with a smaller diameter than the diameter of the flange.