I’ve recently refurbished the front door of our 18th C. house and thought it
would be nice to have a key for the mortice lock.
On opening up the lock it looked to be fairly crudely made but on closer
inspection it became evident that it was made to a high of precision. e.g.
clearance between stump and gating is only about 0.3mm (0.12″). Although I
managed to make a key by hand that just worked from both sides I had to
resort to using my milling machine to make one with a really smooth action.
It’s a four lever lock and the faceplate is stamped:
HOBBS & Cos (yes it really is Cos not Co)
LEVER
FRICTIONLESS FOLLOWER
LONDON
As an engineer I’m intrigued to know how they managed to achieve such
precision for a lock intended for domestic use. Is there anything published
describing how locks were made at that time?
Bob
www.chainganger.co.uk
