As the saying goes, look at the watch to see the movement, watch the escapement, escapement to look at the balance wheel, after looking at the balance wheel, you need to look at the slow hand. Most people know that there is a device in the clock that can adjust the speed of the travel time. The love watch family calls it a regulator, and the watch industry calls it Regulating Pins. In fact, the fast and slow hand is a clockwork mechanism designed for the convenience of professional operation during manufacturing and maintenance, not for users. However, as connoisseurs, we can tell whether the movement is high-end from the fast and slow hands. In the above episode, we will first talk about the principle of the fast and slow hands. In the next episode, we will tell you how to distinguish the quality of the movement through the fast and slow hands .
There are always two sides to things. While bringing convenience, it must also have another problem-that is, the problem of ‘isochronism’. Even the best fine-tuning mechanism is inevitable. Let’s explore its mystery! What is isochronism? Generally, the amount of change in the time difference caused by the change of the swing of the watch is called isochronous error, referred to as isochronous difference. Isochronism is a technical parameter that occupies a large proportion when testing and evaluating the quality of timepieces.
The definition of isochronous time difference is the error when the clock is full and the time error after 24 hours. The specific measurement and calculation are as follows: After the mainspring is fully wound, the instantaneous day difference of the four positions of the watch (CH surface, 3H to top, 6H to left, 9H to bottom) is detected on the watch and done in sequence. Record; after 24 hours, detect the instantaneous day difference of the above 4 positions again, and then calculate the 4 difference values of the corresponding positions, the maximum of which is the isochronous error of this watch.
How exactly do isochronous errors occur? This requires us to start with the vibration system of clocks. The balance watch’s vibrating watch is the core component of the standard frequency used to measure time. Some people call it the heart of a watch, and the number of times that this heart beats is an important factor that determines the accuracy of the clock’s travel time. It is the most critical part of the movement.
Everyone knows that the function of the speed hand is to adjust the speed of the clock. Take the ETA movement with the fine-tuning structure of the fast and slow hands. The balance plate is marked with ‘+’ and ‘-‘ marks. There is an eccentric screw at the tail opening of the fast and slow hands. Rotating the eccentric screw changes the fast and slow hands slightly, and is used for fine adjustment of the speed of the watch. This fine adjustment device is commonly used in mid-range watches.
Let’s look at this movement of Lange. There is a slender pointer on the balance plate. This is also a ‘fast and slow needle’. The other end is the hairspring’s inner and outer clamps. The hairspring passes through the inner and outer clamps, and the middle is a The elastic ring is used to fasten the needle when it is not exposed to external forces; if necessary, move the slender pointer to move it left or right. The pendulum plate of imported watches often uses F or A to indicate ‘+’ (Fast in English and French Avance to accelerate), which means to adjust faster; S or R to indicate ‘-‘ (English Slow is slow, French Retaard is decelerated) to indicate adjustment. slow. By moving the position of the fast and slow needles to change the working length of the balance spring, you can change the fast and slow speeds, hence the name ‘fast and slow needles’.
In order to let everyone understand this principle more clearly, please forgive me for using the formula to explain it (those who are extremely uninterested in logarithmic physicochemical can ignore it), let’s take a look at the calculation formula of this vibration period: T = 2π√J / M0 .
In the formula, T represents the period of vibration; π is the circumference; M0 represents the stiffness of the balance spring; J represents the moment of inertia of the balance; by calculation, we can know that the longer the balance spring becomes, the smaller the balance of stiffness M0 of the balance spring will be. As a result, the clock starts to move slowly; if the hairspring becomes shorter, the rigidity M0 of the hairspring becomes larger, so the vibration cycle becomes smaller and the clock starts to move faster.
There is another method for adjusting the speed. By changing the moment of inertia J of the balance wheel, the speed of the clock can also be adjusted by changing the vibration period. This method is used when talking about the structure of ‘no card spring’. The moment of inertia J of the balance wheel becomes smaller (the counterweight screw is turned inward), so that the vibration period becomes smaller than the clock is moving faster; the moment of inertia J of the balance wheel becomes larger (the counterweight screw is turned outward), so the vibration period becomes larger, and the clock starts Go slow.
In the past, when there was no mechanical clock calibration, it would take several days to adjust the speed of a clock. First of all, a clock with high travel accuracy is required as the ‘standard watch’. All clocks that need to be adjusted are compared with it. According to the degree of travel speed, the adjustment direction and moving distance of the fast and slow hands are calculated. Can be adjusted. The work at that time was an extreme test of the technical skills of the watchmaker.
Now that there is a watch calibration instrument for mechanical watches, you just need to put the watch on the pickup chuck of the instrument, and the number of seconds every day will be displayed immediately; you can change the speed by turning the fast and slow hand, which is convenient and fast. Even if it’s convenient now, don’t think that it can be easily done by anyone. In fact, it is a certain degree of difficulty. I have tried it before. If my heart is still and my hands are shaking, this work is impossible. Therefore, in actual operation, if you want to control the accuracy of the watch within a few seconds, you can imagine the difficulty of manual operation without fine-tuning device. This is why the current watch is equipped with a fine adjustment device for adjusting the speed. If you are interested, you can buy an old watch or two and try it yourself. In fact, usually you can choose a watch and it can also serve as a meditation.
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