Seiko 6R15 Instructions Manual page 23

Accuracy of Mechanical Watches
○ The accuracy of mechanical watches is indicated by the "daily rate."
○ The accuracy of mechanical watches may not fall within the specified range of
time accuracy because loss/gain changes due to the position of the watch,
which is dependent on the conditions of use, such as the length of time during
which the watch is worn on the wrist, arm movement, and whether the
mainspring is wound up fully or not, etc.
○ The loss/gain of mechanical watches is not measured by a daily rate, but by
daily rates of one week or so.
○ Accuracy variation according to temperature
The parts that compose the accuracy of mechanical watches are made of
metals. It is well known that metals expand or contract depending on
temperatures due to metal properties. This exerts an effect on the accuracy
of the watches. Mechanical watches tend to lose time at high temperatures
while they tend to gain time at low temperatures.
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SPECIFICATIONS
Cal.
１.Function
Time display (Hour, minute and second hands),date display
2.Vibrations per hour
3.Loss/gain +25 -15seconds at normal temperature range
(daily rate)
4.Driving system Automatic winding type with manual winding mechanism
5.Jewels
6.Duration
Note: The accuracy above is factory-adjusted.
Note: Due to the characteristics of mechanical watches, any actual daily rate may not fall within the range
of time accuracy specified above dependent on the conditions of use, such as the length of time
during which the watch is worn on the wrist, temperature, arm movement, and whether the
mainspring is wound up fully or not, etc.
88
6R15
3 hands
21,600
(5℃ and 35℃)
23 jewels
Approx. 50hours
○ Mainspring wound condition and accuracy
In order to improve accuracy, it is important to regularly supply energy to the
balance that controls the speed of the gears. The driving force of the
mainspring that powers mechanical watches varies between when fully wound
and immediately before it is unwound. As the mainspring unwinds, the force
weakens.
Relatively steady accuracy can be obtained by wearing the watch on the wrist
frequently for the self-winding type and winding up the mainspring fully
everyday at a fixed time to move it regularly for the wind-up mechanical type.
○ Effect of magnetism
When affected by a strong magnetism from outside, the mechanical watch
may lose/gain time temporarily. The parts of the watch may become
magnetized depending on the extent of the effect. In such a case, consult the
retailer from whom the watch was purchased since the watch requires repair
including demagnetizing.
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87
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