Abstract: A nut fastener device for a blind hole anchor (FIG. 2) has the nut 14 made frusto-conical with the smallest diameter knurled at 30 and with the largest diameter provided with relieved and back tapered flanks 20. The nut is made integral with a sleeve 10 having flange 12 and a further knurled zone 32, and a sheer zone 16 between the sleeve and nut. During the installation the nut is pulled into the sleeve to expand the sleeve and deform it to the cross sectional shape of the nut so as to provide an angular fix. The sleeve is effectively fixed to the sheet material by the flange on the one side and the deformation of the sleeve on the other side of the sheet. The knurled bands which become axially aligned increase the angular hold of the device in the sheet and of the nut in the sleeve.

Abstract: A dart is described having a shaft to carry the flight, with a slot opening diametrically through the thickness of the shaft so that the flight can be deformed to a flat condition and pushed laterally through the slot, the extreme end of the shaft behind the flight being closed and pointed or rounded to provide a deflection surface in the event of contact by a further dart.

Abstract: A blind hole anchor nut fastener comprises a tubular sleeve and a screw-threaded nut at the end of the sleeve, so that when a screw-threaded mandrel is screw-engaged with the nut, and is displaced axially in the appropriate direction, the nut can shear from the sleeve and be drawn into the sleeve in wedging engagement. The basic nut shape is modified by making it non-circular such as trochoidal (for example) at one end and in so-doing making parts of the surface back-tapered so that in the displacement into the sleeve the non-circular shape helps in anti-rotational hold relative to the sleeve and the reduced volume resulting from the back-taper minimizes actual extension of the sleeve under the wedging action so as to reduce the possibility of the sleeve splitting.