Cutaway Mechanical Safe Lock

I'm a retired safecracker. I created this slightly simplified model of a 20th-century mechanical combination safe lock to show how these locks work. It's got the dimensions and general style of Sargent & Greenleaf's left-hand-constructed small-footprint combination lock, model M6730-LH. My model differs from that one as follows:

• Each wheel has a fixed, non-removeable hub.
• Each wheel has a fixed, non-moving fly.
• The lock has no relock trigger.
• The spindle is square and meant to be glued to the hub, as opposed to threaded and pinned.
• The lever, bolt, and spring are one integrated piece.
• The moving parts are left exposed.
• There's no dial ring, so a dialing index mark will have to be made on the door.

Basic functionality is the same as for the M6730-LH. That is, dial 4xR to your first number, then 3xL to your second number, then 2xR to your third number, then left till the dial stops. By observing the wheels and the dial as you align the gates with the door open, you can work out the combination. For a serious challenge, do it purely from the dial side.

To change the combination, simply change the order of the wheels and/or reindex the dial on its spindle. If you want to retain the option to do this without having to reprint the dial, spindle, and cam, then I suggest attaching the dial with a weak glue such as rubber cement.

License Addendum

License restrictions apply to the dial only. The remainder of this model is hereby placed in the public domain.