Known for its precision performance, Rolex watches are equipped with two inseparable components: spring silk and balance wheel. However, the attention of these two important interlinked devices is quite different, and most of the attention falls on the gossamer. It is often forgotten that the constant precision of the rhythm of this fine gossamer is due to the inertiaeffect of the balance wheel attached to it. Moreover, this neglected balance wheel can effectively ensure the regularity of the balance swing components, so the balance wheel is no less important and technical than the famous fine gossamer.
In 1957, Rolex created an important balancer design that allowed movement speeds to be adjusted, making major advances in accurate timekeeping and cementing the brand’s reputation as the world’s best watchmaker. The Rolex engineers created tiny star-shaped Microstella screws for fine-tuning the inertia effect of the balance wheel to greatly improve the accuracy of the watch. The Rolex device is still installed in the brand’s movement, the only difference being that it is now made of gold nuts. One or two pairs of tiny symmetrical star trimmer nuts, about 1 cm in diameter, are threaded into the inside of the balance wheel (technically called the ring wheel). Using a special Rolex tool, the watchmaker will adjust the inertia and rhythm of the balance wheel by gently tightening or unscrewing the nuts (two opposite nuts must be rotated simultaneously for balance) to correct the accuracy of the swing. Watchmaker can also customize the watch, according to the various situations when wearing the balance wheel adjustment.
Rolex developed the balance wheel and the star trimmer nut, combining the advantages of the two main methods of tabulation at the time: a balance wheel with adjusting screws and a tool called a trimmer. The former ensures high precision according to the same principle (the screw placed outside the ring wheel can adjust the rotation inertia), but the disadvantage is that once installed in the movement, it can not adjust the function of the balance swing component. The latter, which is more widely used, adjusts the balance swing assembly in situ through a spinner, but this method is less accurate and can even end up making the device less stable. The cleverness of the trimmer nut is that it can effectively improve the variable inertia of the adjusting screw and balance wheel, allowing the watchmaker to accurately adjust the balance wheel that has been fixed in the housing of the movement. The star shape of the nut helps to fasten the trimmer in any position.
However, the Rolex balancer combines technology and complexity far beyond the Venus design. The ring consisting of a ring wheel and a ring arm is made of Glucydur, a beryllium-copper alloy with paramagnetism and a low thermal expansion coefficient that protects the accurately running balance wheel from magnetic field interference. The effects of metal expansion or contraction due to temperature changes can be offset by changes in the gossamer properties. At Bienne, the balance wheel is made of solid rod material to ensure perfect balance when mounted in the center of the movement, with a manufacturing deviation of +/-2 microns, or two-thousandths of a millimeter. All components are manufactured in strict accordance with quality Rolex standards. Like a ship, which is not prone to veering off course once set sail, the Rolex balance wheel has a high coefficient of inertia (radius squared times mass), which relies on clever optimization to reduce all external disturbances and ensure perfect accuracy over a long period of time.
In addition, the balance wheel is equipped with a very small shaft that is attached to the device, and this assembly also requires special technology to be made. To reduce friction and allow the balance wheel and spring wire to vibrate freely as much as possible, the end of the pendulum shaft (pivot) must be very fine. The pivot is just 0.07 millimeters (70 microns) in diameter, about the size of a human hair. To enhance durability, the hairspring is “rolled up,” a critical process that requires expertise. The gossamer, the components of the balance wheel, the pivot gem, the Paraflex damping device that holds them in place, and the all-important lubricant, all of which are made by Rolex to make the movement precise and reliable, which is the foundation of the Rolex movement’s reputation.