La caja es la base de un reloj. Es esencial para una buena hermeticidad, porque en su diseño es importante hacer los nichos para las juntas de estanqueidad, tanto para el cristal como para impedir la penetración de agua en la caja trasera. Esta caja suele ser colocada a presión, roscada o atornillada, y mientras más plana esté, la hermeticidad será mejor.

Las cajas de los relojes se distinguen por el material, tamaño y forma. Los fabricantes de relojes hacen uso de muchos materiales en la producción de cajas de reloj. Para realizar las cajas de los relojes de bolsillo y posteriormente los de pulsera, los relojeros han disfrutado con el paso del tiempo de las posibilidades de la técnica que la fundición de metales ponía a su disposición.

A lo largo de la historia se han utilizado el hierro, acero, aleaciones metálicas, latón, alpaca, plata, oro de distintos colores, platino y, más recientemente, metales de características especiales, así como materiales sintéticos. Pero también ha habido cajas de marfil, de maderas preciosas, de piedras duras, de porcelana Rosenthal y de esmalte. Dependiendo del material y el proceso de fabricación la caja encarecerá el precio final del reloj.

Dentro de la caja tenemos la carrura, también llamada canto, que es la parte media de la caja donde se aloja la máquina del reloj. A los extremos de la misma van las asas. Por encima de la carrura va el bisel y por debajo la tapa, constituyendo el conjunto la “caja del reloj”.

Cuando la máquina es demasiado pequeña en relación a la carrura, se interpone entre una y otra un añadido de metal o de plástico llamado bata. En los movimientos de cuarzo resulta casi siempre obligado usar la bata.

The lid closes the watch case from the back. The covers can be completely metallic and opaque or they can have a glazed part to show the clock mechanism in operation. Many high-end watches opt for a cover with a glass window. In this way they reveal the mechanism of the watch, which is especially spectacular in the case of watches with many complications. Sometimes only part is shown, sometimes the window is the full size of the lid sphere.

The way the lid is closed is also important. The closure can be press-fit or screwed. Snap closures, which is usually the case for most inexpensive watches, have less water resistance.

Bolt-on closures protect more effectively against water, and much greater depths can be achieved. A screwed closure is distinguished in that the closure cover has circumferential grooves to couple special tools for opening and closing.

Generalmente, la corona es estriada para que pueda cogerse más fácilmente. In wristwatches it is placed at three o’clock, but there are other positions. They serve to tighten the mounting spring, set the clock to time, etc. It has several positions for its different functions.

A bezel is the part of a watch that surrounds the face, usually covered by glass. Most bezels differ visually from the body of the case. Watches without a distinct ring around the glass can be called “bezelless” or “integrated”. The bezel can also be an important cosmetic element, such as the famous “nail” bezel on the Patek Philippe Calatrava, the fluted bezel on the Rolex President and the two-tone ring on the Rolex GTM ‘Pepsi’.

On Rolex Submariner watches, the bezel is provided with minute markers and is designed to be rotated to measure diving time. Blancpain invented a unidirectional bezel that rotates counterclockwise so that the dive time cannot be accidentally easily increased. Bi-directional rotating bezels are also useful in field clocks for solar navigation. Other sports watches are equipped with a bezel with a tachymeter, rangefinder, or slide rule.

Conventional glass is too fragile to be used in wrist watches. In the old pocket watches, these used to have a metal cover to protect the glass, but for wrist watches different alternatives have been sought. Currently the ‘crystal’ is usually made of plastic, mineral glass or sapphire crystal.

Sapphire crystal

Sapphire crystals have the highest scratch resistance of all types of crystals used in wristwatches. On the Mohs scale, which is used to measure the hardness of materials, the diamond has the highest grade, 10, while the sapphire crystal achieves 9. It is so hard that only a diamond can scratch it.

However, the more resistant to scratching, the more brittle a crystal becomes. The sapphire crystal does not withstand shock well, and a small drop could easily break the crystal.

Sapphire crystal is often used for luxury watches. All the big brands (Rolex, Patek Philippe, Omega, etc) have mainly use sapphire crystal.

At first glance it is difficult to distinguish a sapphire crystal from a mineral crystal. You have to look at the manufacturer’s documentation to find out.

Some examples of sapphire crystal watches.

Mineral crystal

Mineral crystal is obtained by melting silica. By controlling the cooling process, you can get minerals with a different hardness and transparency. Depending on the elements used in the process, we can achieve a glass that better reflects sunlight, or that is more resistant, or that has a specific shade, for example.

Depending on the process used, a mineral crystal can withstand quite strong impacts, although its strength is its resistance to scratches.

On the Mohs scale, mineral crystals usually have a value of 5. Although depending on the process used for its elaboration, a crystal with a value of even 6 or 7 Mohs could be obtained.

Plastic or plex crystals.

They are cheap, light and durable. Perfect for sports watches and children’s watches. Unlike mineral crystals, they withstand falls and knocks very well.

Its biggest drawback is that it scratches very easily, although nowadays plastic crystals have improved a lot and can have a great resistance to scratches, although without having the resistance that mineral crystals have. On the Mohs scale, plastic crystals have a value between 3 and 4.

Some examples of watches with plexiglass.

A dial is a background used to orient the timing hands. The face of most watches consists of a large dial, sometimes with smaller insert subdials.

Dial, face (dial) and subdial

Most watches have a dial that takes up most of the face or dial, and these terms are often used interchangeably. However, the face refers to the entire area exposed to view at the top of the watch, while the dial is only the area used to orient the hands. Many watches also have sub-dials for timing, small seconds, or other complications. For example, a Rolex Daytona has a full-face main dial, and 3 small dials for its various complications. Many modern designs feature overlapping dials, skeletonization, digital counters, inserted dials, and other design elements that expose or hide the face or dial.

Dial

Most of the dials are decorated with markers, numbers, letters, etc. Some watches have additional smaller dials for seconds or complications known as subdials. These generally have their own decorative ring, but generally have a simpler decoration due to their size and function. Some special watches, like the Jaeger-LeCoultre Reverso Duoface have multiple main dials and subdials.

Face

The face or face of the watch is sometimes occupied by a single large dial, but many designs use it in other ways. There are watches that only use a part of the entire face for the main dial.

Faces and dials can be smooth, painted, enameled, or decorated with guillochage patterns or textures. Watches with a hole in the face through which movement (especially the exhaust) can be seen are called open heart, while watches with wider open surfaces are called skeleton.

The hands of a watch are the hands that usually carry, to indicate the hours, minutes and seconds. There are needles of different shapes and sizes. There are watches whose hands and / or dial glow in the dark to appreciate the time in dimly lit places. This is achieved by luminescent paint consisting basically of Tritium.

The bracelet of a watch is used to adjust it on the wrist. There are two different types, depending on the material used.

Armys: We talk about armys when the bracelet is made of steel, plated metal, titanium, ceramic, etc., like the boxes.

Strap: We talk about strap when the bracelet is made of some flexible and non-metallic material, such as leather, rubber or neoprene, silicone and textile, …

Complications are display mechanisms on a watch. Some, such as the hour, minute, and second, are taken for granted, while others are so rare and difficult that they are considered “Big Complications.”

Typical complications

The following complications are commonly found on many watches:

• Hour hand, minute hand, second hand (not always considered complications)
• Date and day indicators
• Second time zone or GMT
• World timer
• 24 hour hand
• Day / night indicator
• Subdials for second time zone, GMT, 24 hour time or small seconds
• Retrograde hands (the needle moves along an arc, returning directly to the start, rather than making a full 360º dial).
• Power reserve indicator
• Moon phase
• Alarm function
• Chronograph functions

Big complications

More elaborate functions are often used to demonstrate the technical skill of a watchmaker. These major complications are often so important that they are the focal point of a watch. Some, like the Tourbillon, the perpetual calendar, and the repeaterare hallmarks of prestigious manufacturing. For example, the Patek Philippe Sky Moon Tourbillon Ref. 5002 with twelve complications, the IWC “Il Destriero Scafusia”, the Jaeger-LeCoultre Hybris Mechanica series, or the Vacheron Constantin Tour de L’Ile.

For some, a watch is only considered “Big Complication” if it includes any of the following complications. Some people demand that a watch have more than one of these.

The “Big Complications” include:

• Tourbillon
• Repeater
• Perpetual calendar with leap year
• Sidereal time
• Equation of time
• Astronomical indications, including sunrise and sunset and the zodiac.

The Tourbillon (French Whirlwind) is a clockwork movement created in 1795 by the watchmaker Abraham Louis Breguet. It was developed to compensate for the irregular effect that gravity produces on the flywheel and the escapement wheel when the watch remains at rest in the same position for a certain time, especially on pocket watches. It consists of a mechanism that rotates a cage-shaped frame (usually once a minute) on its axis, on which the watch’s steering wheel and exhaust are mounted.

With the rotation of said cage-shaped frame, the effect produced by the force of gravity on the flywheel / exhaust assembly does not always concentrate in the same direction, averaging. This increases the precision of the watch mechanism.

Given the complexity of the mechanism, some brands were not initially able to carry out such a structure, so they were forced to buy the workshops they were already producing for their own products.
Currently, a watch equipped with such a mechanism can be effectively developed only by a few specialized factories.

In 1980 a Tourbillon was first mounted on a wristwatch. Originally conceived as a device to improve precision, Tourbillons are currently included in some high-end modern watches as an exclusive item. The mechanism is usually visible through a window made through the sphere, showing its operation.

Example of a watch with Tourbillon.

The wheel train is part of the watch movement and contains all the sprockets that drive the hands and complications. These gears transfer the torque (the momentum of rotation behind a movement) from the barrel (The barrel contains the wound spring, which stores the energy of the winding for the movement of a watch) to the escapement wheel.

Wheels are generally held in place by bridges or wrenches attached to a plate. High torque wheels are generally jeweled, although other wheels can rest in simple holes.

An exhaust is a mechanism that, according to the oscillation of the steering wheel, regulates the speed of the train, inhibiting and releasing alternately.

The lever is part of the escapement of a watch movement.

The lever is a two-arm connection between the escape wheel and the balance or pendulum wheel. It receives the energy from the escape wheel and delivers it at the normal time (pendulum or balance wheel). At the same time, it interrupts the flow of the exhaust and the gear train at regular time intervals, as determined by the swing of the balance wheel (or pendulum).

The lever is one of the most stressed parts of a mechanical watch, because it produces impacts by sliding friction and knocks.

Due to its shape, the lever is sometimes called an anchor.

A jewel is a component of the movement mechanism of a watch. The jewels are synthetically produced rubies, which are used to reduce friction in the main bearings of the moving parts of a watch movement.

Quartz watches with few moving parts have only a few jewels. Mechanical watches have from 17 to approximately 50 jewels depending on the complexity of the movement.

The jewels are used as hole stones or head stones, and also in lever paddles and in the ellipse.

Many jewels in one movement do not necessarily mean higher quality. On the contrary, many cheap wristwatches often point to a large number of jewels on the dial with the intention of suggesting a quality that they do not really have. However, many of these are not really necessary or are not in the necessary places. A precision movement with manual winding requires at least 15 functional jewels. An optimal configuration is given with 18 jewels.

For complicated watches such as the self-winding, the chronograph or the repetition, the amount of jewelery necessarily increases.

With the start of production of pocket watches, the movements of the watch had to be classified in order to distinguish them. This was done with the help of the diameter of the movements.

In 1715 the watchmaker Henry Sully used the term ‘caliber’ for the first time to refer to the arrangement and dimensions of the different parts of the movement. Generally, each caliber is designated by the manufacturer’s name (initials, initials or full name) followed by one or more numbers, which can meet different criteria, such as the order that the caliber occupies among those designed or made by the same manufacturer.

In the past, it was relatively frequent that it was the dimension of the gauge, expressed in lines or in millimeters, depending on its diameter in the round ones, or its length and width in the shape gauges. The line, whose symbol is represented by three quotation marks’ ”, is equivalent to 2,2555 millimeters; thus a round caliber with 10 diameter lines (10“ ”) could be called XZ10 or XZ2255 caliber.

Currently the designation of the caliber no longer depends so much on its shape and arrangement as on its construction characteristics, identifying the movements of the same machine by reference to the caliber.