No, when used properly, a watch winder will cause no harm to your watch. A watch movement requires a minimum number of turns per day (TPD) to keep running. Most watches have a safety mechanism to prevent the over-winding of the mainspring, so if the minimum TPD is exceeded, no harm is caused. The RW1 has 3 different settings to ensure proper winding for your timepiece. These include counterclockwise 700 TPD, counterclockwise 1100 TPD, and clockwise 700 TPD.