How long did it take Linus Yale Sr. to invent the lock?

Linus Yale, Sr., didn't invent the lock. The oldest known lock was found by archeologists in the Khorsabad palace ruins near Nineveh. That lock was estimated to be 4,000 years old. It was a forerunner to a pin tumbler type of lock, and a common Egyptian lock for the time. Linus Yale re-invented a pin-tumbler lock in 1848. Linus Yale Jr. patented a new improved cylinder pin-tumbler lock in 1861.