Tom Gordon wrote6 pin even back then! I was wondering how the meachanism worked on the rim cylinder…
It is hard to date when Yale went to a 6 pin cylinder but I am certain it was before 1896. That was the year they were issued the patent for the G Series multiplex keyways. The first key system for that multiplex was actually an engineering drawing with the bittings on it.
The Yale MACS at the time was 4 because of the 100 degree included angle used in their bittings. Having 10 depths of cut didn’t help much with that kind of MACS.
BBE.
[unknown]
