Universal joint flexure hinge suspension system, and method for manufacturing this system

A method for making a monolithic flexure hinge suspension system for a tuned inertial instrument, comprising the steps of:

• (a) mounting on a mandrel, an axially extended workpiece having an axis and an axial hole extending at least partly therethrough, defining a bounding wall having an interior surface and an outside surface;
• (b) forming in said outside surface at each of two diametrically opposite locations of said workpiece an original, two complemental, adjacent depressions separated from each other by a first thin remaining raised bridge having a longitudinal dimension which is skew in relation to the axis of the workpiece;
• (c) forming in said interior surface at each of said two diametrically opposite locations, a secondary two complemental adjacent depressions separated from each other by a second thin remaining raised bridge having a longitudinal dimension which is skew relative to, and crosses the like dimension of said first raised bridge, and which is skew in relation to the axis of the workpiece;
• (d) extending at each of said locations a predetermined one of the primary and secondary depressions to meet the corresponding other depressions to form, at each location, an orifice through the tubular wall bridged across by the corresponding first and second raised crossed bridges;
• (e) removing in each said orifice the remaining material of the workpiece interconnecting said first raised bridge and its proximate second raised bridge to make the crossed raised bridges in each orifice separate from each other;
• and
• (f) cutting said workpiece between said diametrically opposed orifices to form two substantially co-axial, cylindrical tubes, monolithically and integrally connected only by said separated, skew, raised crossed bridges.