Step 7 of 7
Mechanical watch step 7 of 7: A day later
Speeded up 21,600 times: a whole day in four seconds. The hour hand goes round twice, the minute hand 24 times, the balance beats 691,200 times, and the power reserve falls from 40 hours to 16.
Tools: none, just your hands
All 7 steps
What is in it
- Mainspring in its barrel · stores the energy
- Gear train · centre, third and fourth wheels
- Escapement · escape wheel and pallet fork
- Balance wheel and hairspring · the timekeeper
- Winding and setting works · crown, stem, pinions, click
- Motion works, dial and hands · on the dial side
- 21 jewels · synthetic rubies the pivots turn in
Questions
How does a mechanical watch work without a battery?
A coiled mainspring stores the energy you put in by winding. A train of gears carries its force to the escapement, which lets it out a tick at a time, and the balance wheel on its hairspring sets the pace.
What does 28,800 beats per hour mean?
The escapement ticks 8 times a second: the balance swings back and forth 4 times a second. Many watches beat at 21,600 an hour, 6 ticks a second.
What are the jewels in a watch for?
They are synthetic rubies that the pivots of the wheels turn in: hard and smooth, so the pivots wear less and turn with less friction.
How many times should I turn the crown?
Until it stops: typically 20 to 40 turns from empty, depending on the movement. Once a day keeps a hand-wound watch running.
What is the power reserve?
How long the watch runs on a full wind: 40 hours here. A day later it still has 16 hours left.
Safety
Opening a watch exposes its movement to dust and moisture, and its parts are tiny: leave servicing to a watchmaker.
About this guide
The watch here is of our own design, a typical hand-wound movement with small seconds: 28,800 beats an hour (4 swings of the balance a second, 8 ticks), a 15-tooth escape wheel, 21 jewels and 40 hours of power reserve. Its gearing follows from those numbers: the fourth wheel turns once a minute, the escape wheel 16 times a minute, the centre wheel once an hour.
Real watches differ: many beat 21,600 times an hour, and fully winding one takes from about 20 to 40 turns of the crown. The day-long speed-up is 21,600 times: 86,400 seconds in four.
Sources: Farer: how to wind a mechanical watch, Shinola: winding guide (about 30 turns for a 42-hour reserve).
The 3D models, drawings and text are our own.