A number of factors can affect the timekeeping of a clock (temperature,
balance etc.). No matter how well a clock may have been overhauled, final
adjustment is almost always necessary.
The longer the pendulum,
the slower the clock will run.
Most pendulums have a small
rating nut under or in the bob, and small adjustments should be made as
Do not alter the pendulum more than once in 24 hours and
remember that spring driven clocks may run slower as the spring unwinds. Keep a
note of the amount of adjustment made and the resulting affect.
clocks, particularly heavy French ones, have pendulum suspension systems that
allow regulation without moving the case. A watch or double-ended key will fit
the arbor protruding through the dial near the numeral 12. Generally, rotation
of the arbor in a clockwise direction shortens the effective length of the
pendulum, thus making the clock run faster.
Never move a clock with the
pendulum attached, as this will put it out of beat, damage the delicate spring
on which the pendulum is suspended and may cause expensive damage to the
Repairing Your Own Clocks by Mervyn Passmore