Accuracy of mechanical watches
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The accuracy of mechanical watches is indicated by the “daily rate.”
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The accuracy of mechanical watches may not fall within the specified
range of time accuracy because loss/gain changes according 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.
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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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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.
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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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Troubleshooting
Troubles
Possible causes
Solutions
The watch stops
operating.
The mainspring has not been wound.
Wind up the watch as per “How to wind the
mainspring”
→
(P.11), and set the time. If the
watch still does not operate, consult the
retailer from whom the watch was purchased.
The watch temporarily
gains/loses time.
The watch has been left in extremely high or
low temperatures for a long time.
Return the watch to a normal temperature so
that it works accurately as usual, and then
reset the time. The watch has been adjusted
so that it works accurately when it is worn on
your wrist under a normal temperature range
between 5°C and 35°C.
The watch has been left close to an object
with a strong magnetic field.
Correct this condition by moving and keeping
the watch away from the magnetic source,
and reset the time. If this action does not
correct the condition, contact the retailer from
whom the watch was purchased.
You drop the watch, hit it against a hard
surface, or wear it while playing active sports.
The watch is exposed to strong vibrations.
If accuracy does not return after setting the
time, consult the retailer from whom the watch
was purchased.
The watch has not been overhauled for more
than 3 years.
Consult the retailer from whom the watch was
purchased.
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Troubles
Possible causes
Solutions
The date changes at
12
o’clock noon.
AM/PM is not properly set.
Advance the hands by 12 hours.
Blur in the display
persists.
A small amount of water has got inside the
watch due to deterioration of the gasket, etc.
Consult the retailer from whom the watch was
purchased.
* For a solution to a problem other than listed above, contact the retailer from whom the watch was purchased.
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