Adjusting the Timing on a Clock
The timing of a mechanical clock is adjusted by moving the pendulum bob (usually a round disc made of brass) up or down slightly. The bob in mechanical clocks is moved by tightening or loosening the nut directly underneath it.
Tightening the nut (turning clockwise) will shorten the pendulum by pushing the bob up, and the clock will gain time (run faster).
Loosening the nut (turning anti-clockwise) will lengthen the pendulum by pulling the bob down so the clock will lose time (slow down).
Cuckoo clock pendulums do not have a nut. Instead the bob, usually in the form of a leaf or cross, just slides up and down the wooden rod.
Making Adjustments to your Pendulum
The bob should be adjusted very slightly (moved by about 1mm or less) and never more than once every 24 hours. Ideally, the clock should be tested for timekeeping for at least 3 days before any adjustments to the pendulum are made. For more information about testing the timing of your clock read
https://sdemanuele.com/blog/testing-the-timing-on-a-clock.
In cuckoo clocks, variations can occur due to the weather. Once the time is adjusted, they will keep relatively close to time. Once satisfied with the time-keeping, mark the pendulum with a fine pen to make the next adjustment easier.
In quartz clocks, the pendulum is only used for decoration and does not contribute to time-keeping. If the pendulum stops working, it might be time to replace the battery.
