Proof-of concept: Gear hob geometry tested against a 27b, by threading a 14 mm OD BMS rod with the home ground and diamond honed 40 deg HSS tool fed in 95 thou (2,42 mm) with the 20 deg angled compound slide. The light seen at the bottom of hob threads is intentional, as to admit further infeed if necessary. Now: Rinse and repeat with a 14 mm drill rod/ silver steel axle (free from a 550 mm travel heavy-duty gas spring), mill the tooth reliefs, harden to 58-60 HRC, anneal and grind it for (finally - 4 years later!) setup in the NFGC.