Reply To: Pocket Watch Main Spring Problem

[Bob Tascione]

Hi BYJWR1,
Yes you are correct. There should be a slight forward taper to that square which acts as a hook to catch the mainspring. The notched area allows for the hook and starting end of the mainspring to lay down below the outer surface of the arbor eliminating a bump from the end of the mainspring and hook that would be present without this setup. If there is no taper then it’s possible that the hook has been damaged or worn off.
Enjoy!
Bob