Abstract: A fixture for use with a programmable coordinate measuring machine to determine the centerline of a threaded hole formed in a workpiece from a planar surface and the distance between the centerlines of two similar holes, consists of a plug having a cylindrical section threaded to mate with the hole. A cylindrical head section formed concentrically with the threaded section and of greater diameter, has a counterbore formed at one end, concentrically with the centerline if the threaded section. A probe of a programmable coordinate measurement machine may be moved into the cylindrical bore and brought into contact with three spaced points on the interior diameter of the bore with three straight line motions. A coordinate measurement machine calculates the centerline of bore and thus the centerline of the threaded hole from these three measurements.

Abstract: A steel nut body has its wrench flats covered by a sheet stainless steel sheath that extends over one of the nut ends to form a cap. The surfaces of the wrench flats are formed with ridges that bear against the inner surfaces of the sheath. The sheath is welded to the nut to resist forces exerted during torquing by bringing a pair of electrodes into pressured contact with the sheath on opposed sides of the nut to produce pressure concentrations at the ridges. An extremely short, high current electrical pulse is then passed between the electrodes. The heating produced by the current at the interface between the sheath and the nut body decreases the electrical resistance of this path resulting in primary current flow path between the two interfaces, through the nut body, to produce resistance welds at the inner faces without substantially modifying the metallurgy of the sheath.

Abstract: A wheel nut having wrench flats extending parallel to a central threaded aperture is sheathed by a sheet metal cap which extends down the sides and covers one end of the nut. The end of the cap may extend straight across the end of the nut or may alternatively be domed to surround a volume extending beyond the end. The cap is welded to the nut at either a ring of points or a continuous ring extending around the nut end. Alternatively, the nut may have a radially extending skirt between its ends and the cap may be welded to the laterally extending sides of the skirt. These resistance welded joinders are formed by supporting the cap in loose assembly with the nut in an electrically conductive fixture, bringing a tubular electrode into pressured contact with the uncapped end of the nut and passing an extremely short pulse of high electric current through the contacting surface of the cap and nut end using a capacitive discharge welding circuit.

Abstract: A stainless steel sheath for a wheel nut is welded to the nut body in limited areas by bringing electrodes into pressured contact with the conical nut end, which is unsheathed, and a section of the overlying the body. A capacitor then passes a short, low voltage, high current electric pulse through the electrodes to resistance weld the sheath to the body, beneath the sheath electrode without altering the metallurgy of the cap or the body.

Abstract: A wheel nut has a tapered end adapted to seat in the conical depression in a wheel surrounding a stud hole and sides formed with polygonal wrench flats. The flats at the nut end opposite to the taper are depressed or recessed with respect to the remaining flat surface and are connected to the unrecessed sections by a slight shoulder. A stainless steel sheath covers the recessed sections of the flat so that the free edge of the sheath abuts the shoulder. The sheath forms a domed cover surrounding the end of the nut opposite to the conical end to form an enclosure for the end of a wheel stud extending beyond the nut. In an alternative embodiment the sheath edge is bent radially outwardly and then rebent inwardly to form a flange which abuts the wheel surface surrounding a stud depression.