Manual-wind and automatic watches compared
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A manual-wind watch and an automatic are both mechanical. Each runs on a mainspring whose energy is released, beat by beat, through the gear train, the escapement and the balance. The difference is how the spring is wound. A manual-wind watch, also called hand-wound, is wound by turning its crown, usually once a day. An automatic is wound by a weighted rotor that turns as the wrist moves, and most automatics can be wound by hand as well. If the watch will be worn most days and should simply keep running, an automatic suits. If a thinner case, a clear view of the movement through the back, or the small daily habit of winding appeals, a manual-wind watch does.
How each one is wound
In a manual-wind watch, turning the crown turns the winding stem, which drives the wheels on top of the barrel and coils the mainspring around its arbor. A click stops the ratchet wheel from turning back, so the spring stays wound. The mainspring is fixed at both ends, to the arbor and to the barrel wall, so when it is fully wound the crown stops with a firm, definite resistance. That is the moment to stop. Forcing the crown past it strains the spring and the winding parts.
An automatic adds a winding system to the same arrangement. A rotor, or oscillating weight, swings with the wearer’s movement; reversing wheels or a pawl turn its swings, in either direction, into winding in one, and a reduction train passes that to the barrel. Because the rotor does not stop when the spring is full, the mainspring’s outer end is not fixed. It ends in a slipping bridle, which slides around the inside of the barrel wall once the spring is fully wound, so an automatic cannot be overwound by wearing it or by turning its crown. A clutch disconnects the crown while the rotor winds, so the crown does not spin on the wrist. The American Watchmakers-Clockmakers Institute’s course notes on the automatic watch set out both arrangements side by side.
What the difference means day to day
| Manual-wind | Automatic | |
|---|---|---|
| Winding | By the crown, best each morning | By wearing it; by the crown when it has stopped or is not worn |
| Thickness | Often thinner, with no rotor | Thicker, by the rotor and its winding train |
| Through a display back | The whole movement | Partly hidden by the rotor |
| Left off the wrist | Stops when the reserve runs out | Stops when the reserve runs out |
| Parts that wear | The winding parts, used every day | Also the rotor bearing and the reversing wheels |
The power reserve, the time a fully wound watch runs, depends on the calibre rather than the type. Many everyday calibres of both kinds run for a day and a half to two days, and some modern ones for three days or more. Seiko’s 4R35 automatic, for example, runs for about 41 hours from a full wind, as its instructions say.
Neither kind keeps better time by nature. Accuracy depends on the calibre, its regulation and its condition, and on how much force the spring is delivering, which falls as it unwinds and shifts the rate with it. An automatic worn all day stays near the top of its wind, which helps keep its rate steady. A manual-wind watch wound fully every morning runs through the same part of its range each day, which is consistent too. What upsets either is irregular winding. Seiko’s instructions make the same point: an automatic worn for less than about ten hours a day may not stay fully wound, and one used like a desk clock should be wound fully every day at a fixed time. If the choice is still between mechanical and quartz, choosing between quartz and mechanical sets out that difference first.
Winding and setting without harm
- Wind a manual-wind watch at the same time each day, ideally in the morning, so it starts the day on full power. Turn the crown steadily in the winding direction and stop at the resistance.
- Take the watch off to wind it. Winding on the wrist pushes the crown and stem sideways.
- To restart an automatic that has stopped, wind it by hand. Seiko gives about twenty turns of the crown for the 4R35; the number for any calibre is in its instructions. A few automatics cannot be wound by hand at all, such as Seiko’s long-running 7S26, and start from wearing or a gentle swing from side to side.
- Unscrew a screw-down crown before winding or setting, and screw it back down afterwards. Until it is, the watch is not water-resistant.
- Do not set the date late in the evening or in the early hours, while the calendar is changing over. Seiko’s instructions for the 4R35 say not to between 9 p.m. and 1 a.m.; other calibres give their own hours.
- Never force a crown that feels stiff, gritty or loose.
Signs that either needs a service
The two age in different places. In an automatic, the rotor’s bearing wears: a rotor that has grown noisy, wobbles, or can be heard or felt touching the inside of the case back needs attention before it marks the movement or the case. A power reserve that no longer lasts as it did, a watch that stops overnight though it was worn all day, or winding that feels rough, all point the same way. In a manual-wind watch the winding parts take the strain of daily use, and a crown that turns without winding, or winds unevenly, is the sign. For either, a change in timekeeping that measurement confirms is worth having looked at, and when a watch needs an overhaul sets out the intervals and the other signs.
Both are serviced the same way: taken apart, cleaned, lubricated, reassembled and regulated, the automatic’s winding system included. Viattori’s repair service begins with a free assessment and a written estimate, and no work starts until you approve it.
Questions
Can you overwind an automatic watch?
No. An automatic’s mainspring ends in a slipping bridle that slides around the barrel once the spring is fully wound, so neither wearing it nor turning its crown can overwind it. A manual-wind watch stops at a firm resistance when it is fully wound, and forcing the crown past that point is what does harm.
Can an automatic watch be wound by hand?
Most can. Turning the crown winds the mainspring directly, which is the way to restart one that has stopped. A few calibres, such as Seiko’s 7S26, have no hand winding and are started by wearing them or giving them a gentle swing.
Is it bad to let an automatic watch stop?
No. When the power reserve runs out, the watch simply stops, and the movement comes to no harm. Wind it by hand to restart it, then set the time, and the date if it has one, outside the hours when the calendar changes over.
Which keeps better time, manual-wind or automatic?
Neither by nature. Accuracy depends on the calibre, its regulation and its condition, and on keeping the mainspring well wound. An automatic worn every day and a manual-wind watch wound fully each morning can both hold a steady rate.