SJX Watches
In-Depth: Quantifying Performance and Trade-Offs in Movement Design Part II
Previously, in Part I of this series, we analysed and reviewed over 40 watch movements in terms of their potential chronometric performance – via the Horological Density Factor (HDF), which encompasses balance power and power reserve against the size of the movement – and debated the various trade-offs that had been made in order to achieve specific technical or aesthetic characteristics. Many readers then asked how more commonly known and accessible movements compare. To answer that we needed more data from the industry. Fortunately, Swiss movement makers Valjoux, Fabrique d’Horlogerie de Fontainemelon, Unitas, as well as their parent company Ebauches SA – now all part of ETA – once published beautifully comprehensive, detailed data sheets that included balance wheel inertia values. Armed with this data, we have been able to analyse and plot a further 25 movements alongside the previous group (with the disclaimer that it might not be fully up to date since the data sheets date from before the Quartz Crisis in the 1970s) to give a total of 68 to allow further investigation and review. The analysis Several popular movements have been added: the workhorse ETA 2824-1 and -2, the ubiquitous ETA Valjoux 7750 chronograph, the large diameter ETA Unitas 6497-1 and -2, and the ETA Peseux 7001. We also added, among others, the integrated chronograph cal. 4130 in the Rolex Daytona, and the modular chronograph versions of both the ETA 2892 (known as the ETA 2894) as well as...
