Exploring the Dynamics of a Mechanical Watch Lever Escapement using Finite Element Analysis

This thesis focuses on the development of a short-term, operationally stable finite element-based simulation of a mechanical watch lever escapement. This was accomplished in four steps: by choosing a reference escapement based on the needs of the study, by executing a reverse engineering methodology to create a lever escapement in computer-aided design (CAD) software, by capturing experimental data from the reference escapement via custom- built apparatus and then reconciling this data with an analytical model, and by using the knowledge gained from these efforts to develop an implicit dynamic simulation of a lever escapement that aimed to achieve performance metrics defined by watchmaking sources.

The final version of the simulated lever escapement was able to meet two of the three performance goals defined for the study. The simulation met the primary performance goal by achieving stable operation for two seconds. During this window of stability, the simulated lever escapement met the secondary performance goal of the study by achieving timing performance metrics defined by watchmaking sources. Unfortunately, the tertiary performance goal was not met as the balance amplitude of the final simulation was outside of the target range by 5.23% when compared against the lower bound. Although the balance amplitude error of the simulated escapement would be indicative of a mechanism that needs servicing, its performance during the stability period was assessed to be representative of a functional lever escapement and therefore, its dynamics and sensitivities were explored and presented.