Graham, These were turned on the lathe from some round steel rod I had hanging around, before I part them off I centre drill and bore 1.4mm for 10 B.A. tap. Once parted off they are put in the machine vice, center pop for the cotter, drilled 0.45mm very carfully by hand right through, 0.4mm wire ( nickel is ideal) passed through and soldered. Before taking the length of wire out file the two flats using the wire to guide, by sight. It's then just a matter of nipping off the cotter pins to size. ATB, Col.