Schwarz Etienne – It’s all a matter of balance
It’s all at matter of balance by Angus Davies, www.escapementmagazine.com
When it comes to being a tightrope walker, balance is of paramount importance. Likewise, the balance found in a watch is also important, as it is critical to precision. Indeed, of all the components in a watch, and these can sometimes number two hundred or more, the balance wheel and hairspring, sometimes termed the ‘regulating organ’, are fundamental to horological exactness.
The mainspring (not to be confused with the hairspring) is housed within the barrel and harnesses much energy after the watch is wound. When tensioned, the mainspring yearns to relax and left unhindered it would send vast amounts of energy through the gear train to the hands. A consequence of this unrestrained movement is that the hands wouldn’t impact the time accurately. In fact, after a short, frenetic period, the hands would cease moving. Moreover, many delicate parts within the watch would almost certainly be damaged after exposure to such extreme forces.
An escapement links the gear train to the regulating organ. The pallet lever (part of the escapement) lightly pushes the regulating organ which in turn oscillates to and fro at a predetermined frequency. At the same time as supplying energy to the regulating organ, the escapement momentarily suspends the motion of the gear train before a defined period has elapsed and the gears are able to move again. It is the constant repetition of this process that controls the flow of time.
Unlike some watch brands, Schwarz Etienne make all of its own movements, hence it is termed a “Manufacture”. Indeed, the Swiss firm makes movements for other companies and is held in high-esteem within the watch industry.
A company making its own movements is not unique, but it is unusual. However, what is most extraordinary is the fact that Schwarz Etienne makes its own regulating organs. The expertise to make hairsprings is not commonplace. Many firms deterred by the number of technical obstacles awaiting the inexperienced, choose to purchase hairsprings from third part specialists. The market leader in this field is Nivarox-FAR, a subsidiary of the Swatch Group. By making its own hairsprings, Schwarz Etienne and its sister brand, E20 Innovations, enjoy a level of independence other brands can only dream of.
The making of a hairspring
The first obstacle which must be overcome when making hairsprings is discovering at the optimal alloy composition. The recipe for the alloy is always closely guarded, but essentially it needs to be unaffected by variation in temperature and should not oxidise. The material is supplied on reels as a wire.
The next challenge is to reduce the thickness of this wire, a process termed ‘drawing’. While the wire starts with a narrow cross section of just 0.6mm, it needs to be much thinner for hairsprings. The wire is passed through a series of dies with the aperture of each die getting gradually smaller. Typically, the wire will be made to a tolerance of 0.1 micron (0.0001mm). By way of comparison, a human hair will have a thickness of 40 – 100 microns. Should the wire be too thick, too thin or of irregular diameter, the precision of the watch will be significantly compromised.
A wire with a cylindrical profile has to be flattened into a wire ribbon using a process termed ‘laminage’ or ‘rolling’. This process involves feeding the wire between precision rollers. The tolerances are minuscule, again in the order of 0.1 micron. Lasers, bathing the wire in green light, accurately measure the wire and detect any deviation from the desired specification, adjusting the machine’s settings accordingly.
After rolling, the wire ribbon is cut into ‘laces’ which are then coiled. Thereafter, the coiled laces, or springs, are baked in a specialist oven. The temperature of the oven is important, however, the rate at which the spring is heated and cooled is equally critical. Again, these variables are subject to much secrecy.
The inside edge of the hairspring is fixed to the balance wheel’s collet. Once the balance wheel and hairspring are united, they need to be poised. Just in the way a car wheel and tyre are balanced with suitable weights, the balance (balance wheel and hairspring) has to run true. A traditional way of poising a balance was to add screws to the rim of the balance (not to be confused with timing screws). A modern approach is to use a laser to make a precise cut in the underside of the balance wheel rim in order to achieve the desired result.
A key factor which influences the performance of the regulating organ is the concentricity of the hairspring. The hairspring should breathe evenly. If the hairspring, while oscillating, is biased to one side, this will impair precision. It therefore has to be set up correctly by a competent watchmaker.
Even if the hairspring has been fitted flawlessly it may not breathe concentrically. Some of Schwarz Etienne movements feature a ‘Phillips flat spiral terminal coil’ which involves reducing the curvature of the hairspring’s last coil. By adding this feature, the Swiss Manufacture has enhanced isochronism and, by default, precision.
Clearly, this article shows that making regulating organs is not for the faint-hearted. However, throughout its history, Schwarz Etienne has repeatedly demonstrated its horological prowess, a worthy trait manifest with the creation of its eye-catching and virtuous timepieces.