The design of a watt balance experiment requires skills in several scientific fields and needs to carry out numerous studies about every element of this experiment. That can be illustrated by the experimental study presented in this article. In order to have a single point of application of a weight and an electromagnetic force balancing this weight, a system of double gimbals with flexure pivots was made out of copper-beryllium alloy. It allows the articulation of the suspensions of the mass and coil generating the electromagnetic force round four coplanar axes which intersect in one point (virtual centre of rotation). The static characteristics of these elastic pivots have been studied in terms of stiffness and elasticity limit. In addition, the study of the dynamic behaviour under vacuum of this device has been carried out in terms of resonance frequency, damping due to internal frictions and coupling between the two systems of gimbals.