A wall clock arrives at the bench with a familiar apology attached: "I think I overwound it." Almost always the spring is not the culprit, and the clock is not ruined. Key-wound wall clocks are more forgiving than their reputation suggests, provided the person holding the key knows what a healthy wind feels like. Winding is not a chore to be hurried through. It is the one moment each week when you and the movement are in direct contact, and it will tell you a great deal if you let it. What follows is how to find the right arbor, turn it the right way, and stop at the right point.

What "Overwinding" Really Means

A mainspring is built to be wound to its stop. There is no hidden reserve of tension beyond a full wind that a careless hand can push into and break, which is why the word itself is misleading. What people call overwinding is nearly always one of three things: a movement that was already dirty, dry or worn and finally stalled under full tension; a key forced against a train that was jammed before the key ever touched it; or a spring turned the wrong way until something gave.

The distinction matters because it changes what you do about it. A clock that stops the day after a full wind is not punishing you for being heavy-handed. It is telling you that the power was never reaching the escapement properly, and that the extra tension exposed a fault that was already there. A worn pivot, hardened oil or a bent lever will all announce themselves when the spring is at its strongest.

Finding the Winding Arbors

Winding arbors are the square-ended steel shafts that pass through holes in the dial, usually with a brass ring or a small bezel around each opening. On a two-train wall clock — time and strike — you will typically find two of them, set roughly opposite each other, at about the four and eight o'clock positions. A three-train clock adds a chime arbor, often at six o'clock or tucked between the other two.

Weight-driven wall clocks, the ones with chains or cords and hanging weights, have no winding arbors at all. You pull the chain or haul the weight up instead, and the cautions in this article about spring tension do not apply to them in the same way.

Which square is which

• Winding arbors usually sit off-centre, aligned with the trains they serve, and are often larger in diameter than the hand-set square.
• The centre square is frequently for setting the hands, not for winding, and may take a smaller key or a separate one supplied with the clock.
• The key itself should slide on with a firm, snug fit. If it rattles or slips, you have the wrong size, and continuing will round off the corners of the arbor.

If you are unsure, compare the squares side by side, try the key for fit without turning, and if the clock has a maker's mark or a model number, that is worth checking before you experiment.

The Right Key and a Steady Grip

Use the key that came with the clock, or buy a proper clock key in the correct size. Brass keys wear and open out over the years; a slack key chews the corners of the arbor square, and re-cutting a worn arbor costs far more than a new key. Pliers, adjustable wrenches and anything gripped with a cloth are the quickest route to a damaged movement.

Steady the clock with your free hand while you wind, pressing gently against the case so it does not rock on its nail. If the clock hangs high or the fixing feels doubtful, take it down, lay it face up on a folded towel and wind it there. Keep the key in a drawer nearby rather than leaving it in the arbor, where it can catch on a sleeve and bend a shaft or fall and dent a floor.

Winding, Step by Step

1. Steady the case, or lay the clock face up on a soft surface.
2. Seat the key fully on the square, straight on, without forcing it.
3. Turn gently through the first few degrees and listen. A healthy movement clicks as it winds. If you meet hard resistance almost immediately, stop and try the other direction — some movements, particularly certain French designs, wind anticlockwise.
4. Continue in steady half-turns, keeping the key square to the dial and applying the faintest inward pressure so it does not climb off the arbor.
5. Wind each arbor until it comes to a definite, firm stop. That stop is the end of the spring's travel, not an obstacle.
6. Wind the strike and chime trains first and the time train last. It makes no mechanical difference, but it means the hands are the final thing you touch.
7. Remove the key, close the door or shutter, and set the time by moving the minute hand forward only, pausing at each quarter and hour to let the strike or chime finish.

Reading Resistance

The feel you are looking for is smooth and even, with a light ratchet click at each part-turn and a gradual increase in tension toward the end. When it stops, it stops cleanly. There is no benefit in leaning on the key for a final quarter-turn, and no reward for it either.

Signs to stop and take notice

• Gritty or squeaky resistance suggests dry or contaminated pivots. Winding harder will not clear it.
• Sudden slack, where the key spins freely after a few turns, points to a broken spring or a slipped ratchet click.
• A clock that once took eight turns and now takes two has a problem worth investigating before the spring is fully wound.
• Any grinding noise from inside the case is a reason to stop and have the movement looked at, not to press on.

Resist the urge to oil anything yourself, whatever the tin in the shed says. Household lubricants thicken, migrate and collect dust, and a clock oiled in the wrong place is a more expensive repair than one that was simply left dry.

How Often, and How Far

Most domestic wall clocks are eight-day movements: wind them once a week, on the same day, and note the day somewhere you will see it. Thirty-hour clocks need winding daily, ideally at the same hour so the routine fixes itself in your memory. Wind each arbor fully every time rather than topping up a turn or two each morning. A well-wound spring delivers more even power to the escapement, and a clock that runs on a nearly slack spring will often lose a minute or two a day for no reason other than that.

If you forget and the clock stops, nothing is broken. Wind it fully, set the hands forward as described above, and carry on.

A Small Routine That Protects the Movement

Choose a day, wind the clock fully, and pay attention for the ten seconds it takes. If the key feels different from last week — rougher, looser, shorter in its travel — make a note and have the movement serviced before the problem becomes a repair. Keep the correct key with the clock, never force a stop, and treat a sudden change in resistance as information rather than an inconvenience. Do that, and the phrase "I think I overwound it" will stay a story about somebody else's clock.

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