Mechanical watches have a mechanism that is moved by power generated when the mainspring is unwound, and small metal parts physically work together to control the accuracy. Fragile metal parts of a mechanical watch are easily influenced by external environment such as temperature, gravity, and shock. Also, conditions of use such as normal usage time and winding state of the mainspring can influence the loss/gain of the watch.
Accuracy of mechanical watch is “mean daily rate.”
Factor influencing accuracy (1): Wound amount of the mainspring
Factor influencing accuracy (2): Temperature influence
Factor influencing accuracy (3): Difference by position (orientation of a watch)
Accuracy of the quartz watch is indicated monthly or annually such as a monthly rate of ±15 seconds or annual rate of ±10 seconds. This indicates the degree of total difference in accuracy when the quartz watch is continuously used for a month or a year.
To the contrary, accuracy of the mechanical watch is normally indicated as a “mean daily rate.”
Accuracy of the mechanical watch slightly varies each day as it is influenced by various conditions of use, and it is normally unstable. Then it is required to judge whether the accuracy is satisfactory or not by checking the mean values in the case of use for a week to ten days, but not for only one day.
For normal usage accuracy of Grand Seiko mechanical watch, -1 to +8 seconds per day is specified as target values. If the mean value exceeds the abovementioned target value in the normal usage condition when the watch is used for a week to ten days, we recommend adjusting it.
Please note that the parts that are age-deteriorated due to long duration of use may not be adjusted to your desired accuracy. For details, refer to After-sale service.
In order to use the mechanical watch at better accuracies, it is required to supply a constant strong energy wherever possible to respective parts.
In the state where the mainspring is fully wound, accuracy is stable, however, when the mainspring is unwound to weaken energy to be supplied, the parts controlling accuracy tends to be externally influenced, and accuracy becomes unstable.
In order to use a mechanical watch at a steady accuracy, it is recommended to use it in a condition where the mainspring is sufficiently wound.
Mechanical watch parts are metal which slightly elongate and contract by change in temperature, and this influences accuracy. Normally, under high temperatures, it tends to lose time, and under low temperatures, it tends to gain time.
Parts related to accuracy of a mechanical watch are also influenced by the earth’s gravity. For example, gain or loss differs when a watch is horizontally placed and when it is vertically placed in the 12 o’clock up position.
When the watch is not worn on the wrist, accuracy errors that occur while wearing can also be compensated to some extent according to the position. Try to place it in various positions to find the position appropriate to your watch.