Two models of the grand piano key mechanism are presented: single-degree-of-freedom and 6 rigid rotating bodies coupled by 13 contact zones with nonlinear springs. Coulomb friction is considered in pivots and at several contact zones, introducing discontinuities in the velocities. Therefore, some problems are raised by the usual regular-dynamics formulation. The results given by the single-degree-of-freedom show that these problems must be addressed. A non-smooth dynamics approach is proposed using the XDE (eXtended Dynamic Engine) software developed at CEA LIST. Simulation results are compared to experiments for several playing nuances. Sensitivity analysis and model simplification will be discussed.