Annular Guide Diaphragm for a Strain-Gauge Load Cell

On thin sheet, scribe two circles with dividers: the outside fits the shell, the inside fits the piston.

Drill a starting hole and cut out the centre, then cut the outside with snips. File both edges smooth and flatten it on the anvil.

Ruge's patent gives the part's shape and job but no material or size. Mild steel and silver-solder brazing are our choice; size it to the load you need. Lathe method after Palmateer, Elementary Machine Shop Practice (1918). Make two, one for the top and one for the bottom of the piston.