The reasons for inaccuracy are as follows:
1, the second hand and minute hand are different from the minute hand and hour hand, and the latter belongs to "dead engagement". The positions of the minute wheel, the straddle wheel and the hour wheel are relatively fixed, and there will be no dislocation or movement under normal circumstances. The situation of the second wheel is different from that of the minute wheel, because the minute wheel will "slip" and it will appear as long as you dial the needle.
2, the existence of backlash, in order to ensure the normal meshing and smooth transmission between gears, clocks and watches basically use modified cycloidal tooth profiles, gear teeth have meshing angles and meshing angles, but they must also have backlash, otherwise there will be the phenomenon of top teeth or scraping teeth. The backlash of a pair of gears is very small, but it becomes several pairs of gears, and the backlash is superimposed together, which becomes obvious. It will pass through a small idle corner before the pointer behind it is pushed, which often happens after the pointer is set in a certain direction. The most typical is a two-needle quartz watch. If the minute hand indication is not good, it will always be half a minute late.
3. It belongs to the dial. There are errors in the installation and printing of dial characters and scales, which can not absolutely ensure that the scales of all parts of the dial are concentric and equally divided; The most important thing is that there are two claws under the dial, one is the positioning tolerance of the claws, the other is the verticality, and the other is that it may move slightly radially above the center of motion.
4. The second hand of quartz watches basically jumps seconds, and the accuracy of the second hand seems to be more obvious, especially for quartz clocks with large market. Often the second hand is aimed at the scale of one part of the dial, while the other part is not so straight. This is normal. In fact, when the second hand of a mechanical watch goes, it is also intermittent and has a pause. It depends on the vibration frequency of the balance wheel. If it is 28,800 times/hour, the second hand will "tremble" 8 times per second.
It seems that the second hand of a watch (clock) is required to point to the scale accurately, which has no specific application significance in life. It is only needed for a sports stopwatch, but it needs extremely fine teeth and extremely high swing frequency, and it must be able to stop for seconds. Only when the second hand stops can we observe and take the number accurately. And there is this special purpose or need time interval timer, now I will choose digital quartz watch. The pointer code watch needs to be positioned when installing the center second hand, so that the initial position of the stopwatch and the position after zeroing are aligned with the "12" time symbol; There are also requirements for the positioning of the second hand of the radio meter, all of which have second-level timing accuracy requirements. In addition to the above two kinds, the second hand of a watch is generally installed at will.
6. The position of the second hand is the highest, far away from the dial, and it is easy to cause visual errors due to the observation angle.
Extended data
Maintain common sense
Precautions for watch adjustment:
1. You can't adjust the calendar, day of the week and phase of the moon between 2 1: 00pm and 3: 00am in Casio watch time. At this time, the calendar function is running, and when the gear engagement is low, frequent actions will damage the internal parts of Casio watch.
2. Weekly calendar jumps can be divided into fast and slow due to different formats. The first calendar jump is completed in 5 minutes, and the second calendar jump is completed in 3 hours.
3. Casio watches with spiral crown cannot be pulled hard. Please turn the locked crown counterclockwise, adjust the time, and then turn the crown clockwise to push the lock to avoid water.
4. Casio watches with calendars need to adjust the date. Please adjust the calendar to the day before the required date, and then turn the clockwise to adjust the date. At that time, the date will change when the pointer passes 12 at midnight, so as to avoid the confusion between day and night caused by directly adjusting the date.
References:
Baidu Encyclopedia: Casio Watch Maintenance Knowledge