How Do the Manufacturers Test Their Mechanical Clocks?

Which tests must be carried out and which test devices are used

The ticking of a watch is the most beautiful sound for a mechanic lover, but it also serves the gait diagnosis. This requires a timescale–only one of the devices that a watchmaker uses in his work. The following article shows which tests have to be carried out by the movement parts and the finished work before they are installed in the watch, and what checks are then waiting for them.

From the blank to the Exbor to the finished watch–this is a long way to go, where every step must be done with great precision. Only precisely manufactured components result in a gear-accurate movement. But his precision is no coincidence: every single Exbor and finally the big picture must pass numerous tests. These controls are precisely planned and carried out with various instruments and devices. For example, in manufacturing, it is an automatic measuring device in which a part is clamped. At a desired point, the measurement can be accurately measured up to the thousandth of a millimeter and fed directly into a computer.

Even the production of the movement parts accompanies constant controls

Or, the optical control is carried out by means of a profile projector at a light table, on which a frequently magnified technical sketch is used to match the silhouette of a single part. When it comes to the Assembly of the Movement, it has to be controlled and controlled again and again, over and over again. With all the patience that is generally awarded to the watchmaker. At Nomos Glashütte The assembly begins with the Assembly of the clutch system. This allows both the lift and the pointer to point while holding down the crown. The shaft must be properly seated in the work, which is checked by the watchmaker himself after this step. Now he can install the drive. The wheels are placed, the three-quarter board mounted. Finally, the watchmaker tests whether the wheels are spinning without blocking, and whether they are in the right height. At this point, the first special equipment is used at Nomos in Glashütte: A recently acquired automatic measuring table. This not only measures the height of the wheels, but also ensures the correct lubrication by automatically adding oil at certain points in the movement.

After this first automatic control during assembly, the anchor can be installed. It turns the drive’s rotation movement into a float and plays an important role in the mechanical movement. When the anchor is seated, it goes to the Reglage where the balance is built: Soon the work comes to life. Nomos receives the balance with a pre-assembled spiral, balanced and controlled by a supplier. This also ensures the “approximate correct length of the spiral”, says Daniel Malchert, watchmaker at Nomos.

Further away: from inserting the balance spiral to the precise gear

Therefore, the spiral can now be fixed with a blocks, as well as with the back and Klötzchenträger. “When you have done everything right, the work is now for the first time,” explains Malchert. The gear is still very imprecise, because first it has to be adjusted. The watchmaker changes the active length of the spiral spring by turning the regulating screw and thus adjusting the so-called back. In one Direction it reaches a plus: the spring is shortened and the balance moves faster. In the other direction a minus: the spring is lengthened, the balance moves slower.

At the Reglage, the watchmaker uses a so-called timescale–its most important tool not only for installation, but also for service. The timescale is called a device that checks the exact gait of mechanical clocks with Swiss anchor inhibitors. Here at Ehotelat you can get more different models of the watches fashion. This is done by listening to the ticking of the clock via a microphone and then evaluating it by extrapolating the deviation.

How a timescale Works

The ticking is caused by the contact of anchor and anchor fork with wheel and lever stone. The first noise arises when the lever stone touches the fork of the armature, the second noise when lifting the pallet from the wheel and the third when falling the Ankerrads on the pallet. Modern timescales have a small screen on which a possible deviation in seconds per day is indicated and the accuracy of the gear is also visualized as a line. A horizontal line is the result to be achieved–because it ideally means that the watch will function perfectly precisely.

In addition, the timescale is able to display the so-called “waste”. This signifies a deviation between the outward and the movement of the balance. In the ideal state, the movement takes One direction as long as the other. This is indicated on the timescale by two parallel double lines that should be drawn.

The timescale checks the work in up to six layers–for example with a dial up, then hanging, i.e. with the dial perpendicular, and so on. This is the only way to see certain errors. For example, if the balance is unbalanced, it has no consequences for the aisle in the flat position. The error then reveals itself hanging. In addition to the manual time scale, in which the watch is clamped by hand and its position is changed, the Nomos watchmakers also work with automatic timescales, which rotates the clock every 35 to 40 seconds and then measures each gear and waste. These numbers are displayed directly on a screen–along with the average values already calculated and a visual indication of possible extreme deviations.

At Nomos In addition, a ten-fold timescale is in use, which – as the name suggests–can test ten movements at a time. At the Swiss company Witschi Electronics in Büren on the Aare, the most famous manufacturer of measuring instruments for watchmakers, one divides the time scales into “table” and “Industrial devices”. The table-top devices are those used by the watchmaker on his workbench. Industrial devices, on the other hand, are controlled via a computer, allowing the rapid testing of several plants and guaranteeing traceability of the measurements. Of course, time scales for quartz watches are also offered, in which the precision is determined on the basis of the motor pulses. Some watch collectors would like to have their own timescale next to his collection, but they have their price. For a timescale of Witschi electronics without accessories is to be expected with at least 1,800 Swiss francs, even the competitor Greiner Vibrograf moves in this order of magnitude. Another supplier of test equipment is the German company Elma Hans Schmid Bauer GmbH & Co. KG in Singen. Here a timescale for Mechanikuhren with accessories costs around 2,500 euros.

A cheaper alternative is the German company L-Trade, which, under the brand name TYMC, offers time scales for professionals and laymen. The entry fee for a timescale with screen is here at 329 euros. About as much cost equipment and software for the computer that can deliver very detailed measurement protocols. Such a PC timescale provides for example the Viennese watchmaker Mikl. If you like to tinker and know about electronics, you can even find blueprints and instructions for building your own timescale on the Internet.

But back to the professional equipment, as they stand in the workshops of Nomos. These are used extensively. Remember: First, adjust the test on the manual time scale after inserting the balance and repeatedly regulate and control until the gear levels are excellent. This is followed by a week in which the works are raised daily and the spiral can get used to their movement.

At the end of this week, the manual timescale will be adjusted again. “Then the work is tested on the automatic timescale in six layers,” explains Daniel Malchert the process. “As a Regleur you can see from these values whether, for example, a priority error makes it necessary to balance the balance again or readjust,” explains Malchert. You can be prepared for everything: “Everything is possible here, because it is about the slightest tolerances, which nevertheless have a massive impact on the passage of a clock.” To illustrate this, Daniel Malchert has an example: “At a clock with a frequency of four hertz, that is, 28,800 half vibrations per hour, the balance is required for a swing in a direction of 125 milliseconds. If there is a difference of a thousandth of a second, that is 0.1 milliseconds, this will be summed up throughout the day on more than one minute of gait deviation. ” To ensure that this does not happen, Nomos will check and regulate until best gear is recorded.

After the shelling, new tests are waiting for the watch

Only then will the plant be passed on to the enclosure. After that, the ten times scale is used again: it checks the finished watches. And not only that: depending on the model, there is also a water leakage test. It is divided into a deformation and pressure differential measurement. During the deformation measurement, a device analyzes how much a watch housing is dedeformed under pressure or in a vacuum.

In the differential printing process, it is measured whether air flows from a test chamber into a watch, thus reducing the pressure in this Chamber. A corresponding tester analyzes the course of the pressure difference and even calculates a so-called “leak rate” as it is called at Witschi Electronics. If one detects such leakage, it is said to seek the leak. Nomos uses a device from Greiner Vibrograf with a glass cylinder. Here a watch is mounted and exposed to increased air pressure. Then the watch is immersed in water, which pushes the air through the overpressure into the housing again. Now it is necessary to find and seal the leak from the bubbles that are emerging.

Then it goes on to the next test, step by step. Only when a watch withstands every test will it be released into the Wide world.

Tags: german watch manufacturer, Glashütte watches, Manufactory caliber