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How to Wind a Mechanical Clock

Winding a clock takes a minute a week, but doing it carelessly can be expensive. Here is what conservators and clockmakers actually recommend.

By David Ray · clocks.fyi

Know what kind of clock you have

Most mechanical clocks run either on a coiled mainspring or on falling weights. Winding stores energy in the spring, or lifts the weights back up, so the clock can keep going until the next session.

How long a clock runs on one winding is called its duration. The Institute of Conservation (Icon) in the UK splits household clocks into day-running types, which go for 30 hours or less, and 8-day clocks. The routine for each is different.

Now look at the dial. Each winding hole leads to a winding arbor, and each usually powers its own train of wheels: one for timekeeping, one for the hour strike and sometimes a third for a chime. Howard Miller notes that its wall and mantel clocks can have one, two or three winding holes. On Chelsea Clock's ship's bell clocks, the left hole winds the strike and the right hole winds the timekeeping.

See also: what the arbors, trains and other clock parts do on OnlineClock.app.

Keys, cranks and weights

A key that fits badly can slip, round off the arbor or scratch the dial. Icon recommends a well-fitting key of the right type: a butterfly key for mantel clocks, and a crank key for longcase clocks and larger bracket or mantel clocks.

Some keys have two ends. Swiss maker L'Epée tells owners of its carriage clocks to wind with the longer end of the key and set the hands with the smaller end.

The British Antique Dealers' Association (BADA) adds a practical tip: hold a spring-driven mantel or bracket clock steady while you wind it. New clocks may also arrive with transit packing; Chelsea Clock asks owners to remove the black tubing from the winding arbor and keep it for future moves or long absences.

Longcase and many wall clocks are wound with a crank that raises the weights inside the case. BADA suggests opening the trunk door while you do it, to check that the weights are not catching on the case or the pendulum. Howard Miller's manual warns against lifting the weights by hand while cranking, and Icon says to wind so that the weights do not end up touching the underside of the clock.

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Which way to turn

There is no single rule for every clock, and the conservation guides from Icon and BADA do not give one. Modern makers usually tell you. Howard Miller's manual for its key-wound wall and mantel clocks says to turn the key clockwise until the spring is tight and will not turn any further.

Weight-driven clocks may be marked. German restorer Tribbensee says its cranks carry an engraved arrow, and the crank should be turned exactly the way the arrow points. When the clock is fully wound, the pulley carrying the weight should still be visible below the dial.

For an antique with no markings and no instructions, turn gently and feel for resistance rather than forcing anything. If you are unsure, ask a clock specialist before you go further.

How often to wind

Consistency matters more than the exact moment. Icon advises winding day-running clocks at the same time each day and 8-day clocks on the same day each week.

Wind before the clock runs down. L'Epée says its carriage clocks need winding every 8 days. Howard Miller says once a week. Chelsea Clock recommends a weekly wind at about the same time and warns that under-wound clocks can strike inconsistently or keep poor time.

If a clock has stopped, Chelsea says to wind it fully before you touch the hands, so that both the strike and the timekeeping have power when you start setting them.

The overwinding myth

Many people assume a stopped clock was overwound. Icon is blunt: there is really no such thing as overwinding a clock. Chelsea Clock likewise says winding fully is the right way to do it, and Howard Miller tells owners to wind until the spring will not turn further.

What Icon does warn about is roughness. It says considerable and potentially expensive damage can come from winding that is not gentle and steady, and it cautions against coming to a sudden stop at the end of winding a spring clock.

So if a fully wound clock refuses to run, the winding is rarely the culprit. Icon notes that lubricants deteriorate, especially after about three years, and a dirty or dry movement is a common reason for a clock to stop. That is a job for a clockmaker, not for more force on the key.

See also: fixes for a clock that stops or loses time on OnlineClock.app.

Setting the hands without damage

Conservators say to move only the minute hand. Icon advises never moving the hour hand or seconds hand, and never turning the hands backward without proper advice. BADA says to turn the hands of antique clocks clockwise only, especially on striking clocks.

On a striking clock, let it finish striking at each hour and half hour before moving on; Tribbensee gives the same advice. Chelsea Clock adds that adjustments should never be made in the ten minutes before a strike.

To put an antique back an hour, Icon suggests stopping the pendulum and restarting it once real time has caught up with the dial. It also advises against moving the hands forward more than an hour or so.

Modern clocks can be different, which is why the instructions matter. Howard Miller tells owners to set the time by moving only the minute hand backward on its chiming clocks, while Chelsea suggests moving the minute hand back through one striking position if the hands lock. For antiques, follow the conservators' forward-only rule. On L'Epée carriage clocks with a calendar, the maker says not to set the date between 8 pm and 2 am.

Holidays, silence and servicing

Icon advises stopping a pendulum clock before you go on holiday, or overnight for short-duration clocks. It also says leaving the strike side unwound is not a good way to silence a clock. Tribbensee notes that many of its clocks have a lever or stop weight for silencing the strike, and Icon suggests asking a conservator about other options.

Longcase and wall clocks should be fixed securely to the wall, as both Icon and BADA recommend, and BADA suggests a specialist shipper for moving a valuable antique.

Finally, oil does not last forever. Icon recommends having a clock examined and re-lubricated about every three years, and the movement dismantled and cleaned after five years and no later than eight. L'Epée also suggests a service every three years. Do not reach for household oil: Icon warns against using proprietary lubricants yourself.

See also: finding and choosing a clock repairer on OnlineClock.app.

Questions people ask

Can you overwind a clock?

Not in the way most people mean. The Institute of Conservation says there is really no such thing as overwinding, provided you wind gently and steadily. A fully wound clock that will not run usually needs cleaning or repair.

How often should I wind an 8-day clock?

Once a week, ideally on the same day, so it never runs down. Day-running clocks of 30 hours or less should be wound at the same time every day.

Which way do I turn the key?

Follow the maker's instructions or any arrow on the crank. Howard Miller, for example, says to turn the key clockwise on its key-wound clocks. On an unmarked antique, turn gently and never force it, or ask a clock specialist.

Can I move the hands backward?

On antique clocks, conservators advise against it, especially on striking clocks. Some modern chiming clocks, such as Howard Miller's, are designed to be set backward, so check your instructions.

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