How things work ยท No. 1
How a lock knows its key
A working model of the lock on most front doors, cut in half. Nothing here is drawn by hand: every part moves the way the real one does.
The key
Cut your own key
What is simplified
- A real keyway is a zigzag slot, so only a key with the right side profile can enter at all. Here it is a plain slot so you can see the pins.
- The cut depths here are about 0.6 mm apart so the difference is visible. On a common door lock they are closer to 0.4 mm.
- Five pins with ten depths each is 100,000 combinations on paper. Makers allow fewer, because two neighbouring cuts cannot differ too sharply or the key would not slide in.