A winder comes out of its box with factory settings. These suit a theoretical average calibre — which means almost no particular watch. Two settings deserve your attention.
Turns per day
The first setting is measured in turns per day, abbreviated TPD. It is the number of complete rotations the holder makes over twenty-four hours, divided into short cycles with pauses in between.
The useful range is generally 650 to 1,000 turns per day. Below that, some calibres remain insufficiently wound and eventually stop despite being on the device. Above that, the movement is not damaged — modern slipping clutches limit mainspring tension — but the motor runs unnecessarily.
The exact value depends on your calibre. It is sometimes stated in the manufacturer's manual. Otherwise, your watchmaker can advise you.
The direction of rotation
There are three modes: clockwise, counterclockwise and bidirectional.
Most modern automatic movements wind in both directions thanks to reversing gears. For these, bidirectional mode is the right choice: it distributes the load instead of always working the same gear teeth.
Some calibres, especially older ones, recharge only in one direction. Turning them in the opposite direction half the time amounts to dividing efficiency by two. In this case, select the corresponding direction.
A simple method for checking
Set the device, place the watch on it and let it run for forty-eight hours without touching it. Then compare the displayed time with a reliable reference. If the watch is on time or very close, the setting works. If it has lost time or stopped, increase the turns per day by one step, or switch to unidirectional mode.
Three mistakes to avoid
Stopping a rotor by hand. Cut the power before handling.
Fastening a watch onto a cushion that is too wide. The strap or bracelet can become distorted, and one kept under strain for months may not recover its shape.
Set the maximum "to be safe". This does not improve anything and makes the device run unnecessarily.