Can You Overwind an Automatic Watch?
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Short answer: no, you cannot overwind an automatic watch. But there are a few winding mistakes that really can cause damage. Here is the difference.
Why an automatic can't be overwound
The mainspring of an automatic is not fixed at its outer end. It is held against the wall of the barrel by friction, through a part called a slipping bridle. Once the spring is fully wound, any extra winding, by the rotor or by your fingers, simply makes it slip around the barrel instead of tightening further. That is how an automatic can be worn all day, every day, and never be overwound by the rotor.
So if you wind an automatic by hand, you can keep turning without harm. Around 30 to 40 turns is plenty to fill it from empty.
Manual-wind watches are different
A hand-wound watch has its mainspring fixed at the end, so when it is full the crown stops turning and you feel firm resistance. That is the signal to stop. Forcing past it is the real "overwinding" people worry about, and it can damage the spring or the winding gears. See automatic vs manual-wind.
The winding mistakes that do cause damage
- Winding with the watch on your wrist. It puts sideways pressure on the crown stem. Take it off first.
- Winding a screw-down crown without unscrewing it, or screwing it down too hard afterwards. Unscrew gently, wind, push in, screw down until snug.
- Changing the date late at night. Between roughly 9pm and 3am the date mechanism is engaged on many movements. Move the hands to 6 o'clock before changing the date.
- Turning the crown backwards hard. Most automatics only wind clockwise; turning back is harmless, but do it gently.
Does winding by hand wear out an automatic?
Occasional hand winding, to start a stopped watch, is exactly what the crown is for. Winding it fully by hand every day is unnecessary if you wear it, and adds a little wear to the winding parts over many years. Let the rotor do its job and hand-wind only when the watch has stopped.
Step by step: how to wind and set an automatic watch.