Setting Up & Regulating Pendulum Clocks

*It is essential that a clock is “set up” when put into operation after a move to a new position. No matter how thoroughly a pendulum clock is overhauled, if it does not receive this final attention it may suffer from loss of power and subsequently stop.

All clocks leaving workshops will have been set “in beat” on a level surface. Provided that a clock is transported carefully with the pendulum removed and subsequently placed on a firm level surface, no adjustment may be necessary.

Pendulum Clock Siting

A mantel clock must be placed on a firm even surface. Longcase or Grandfather clocks should be screwed to the wall, particularly where there is any likelihood of movement. Wall clocks should be hung on secure fixings (not nails). Uneven and unsound walls should be avoided.

Regulation

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 rating nut under the or in the bob, and small adjustments should be made as necessary. 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 amounts of adjustment made and the resulting effect. Some 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 escapement.

Setting Up

A clock is “in beat” when the intervals between ticks are exactly equal. An “out of beat” clock can be heard ticking unevenly, with alternately long and short intervals between ticks.

Carefully fit the pendulum, wind up and gently set the clock going. After a few moments, check the sound of the ticking. If uneven, proceed as follows:

Stop the clock by holding the pendulum in the central position. Carefully move the pendulum from side to side just enough to allow the ticks to be heard, and check which direction requires the least movement from the vertical position. It is in this direction that the crutch (the part that delivers power to maintain the swing of the pendulum) needs to be bent.

The aim is to alter the position of the crutch in relation to the escapement and it is important to establish what provision the manufacturer has made to enable this to be done.

Many movements have friction joints which allow the crutch to be adjusted without bending. To adjust these, move the crutch in the desired direction to the limit of its free travel and then apply slight pressure. If the movement is fitted with a friction joint the crutch will move further with an even resistance. If the crutch starts to flex, let go at once. If the movement of the crutch is restricted by, for instance, pins protruding from the back-plate, the escapement will have to be held with one hand while the crutch is moved. Where no friction joint is fitted, the crutch needs to be bent. Never put any firm pressure on a crutch against the escapement as this may do serious damage. Always bend the crutch against the resistance of the other hand or between fingers of the same hand. Whichever method is used, several attempts may be necessary as there is no way of measuring the alterations you are making. Only make very small adjustments each time.

*EXCEPTIONS:

Wall clocks may be given their final adjustment by moving the bottom of the case very slightly to one side. Some fine movements have screw-threaded beat adjusters, allowing for very precise alterations. Some modern movements have automatic adjustment.
Antique French clocks are sometimes adjusted by slackening the two screws on the back door and rotating the whole movement imperceptibly. Re-tighten the screws to prevent the clock from rotating when being wound.