Pendulum Basics — Beat, Level and Accuracy

What 'in beat' actually means

The escapement should release with the same energy on each side of the pendulum's swing. When it does, the tick and tock are evenly spaced. When it does not, one side receives less impulse than it needs and the pendulum eventually stops — often overnight, when the house is still.

Levelling comes first

Put a small spirit level on the case base or the seat board and shim until it is level in both directions. A floor clock on carpet will settle over the first few days, so re-check after a week.

Setting the beat

Some clocks are self-adjusting: swing the pendulum firmly to one side and the crutch resets itself. Others require bending the crutch slightly or shifting the whole case. Adjust in tiny increments and listen after each change until the tick is metronome-even.

Regulating the rate

Raising the pendulum bob makes the clock run faster; lowering it makes it run slower. One full turn of the rating nut is typically thirty seconds to a minute per day. Change one variable at a time and give the clock a full week between adjustments — a clock that gains two minutes a week is running well within normal tolerance for a domestic mechanical movement.