Abstract: A method for measuring the torque of a balance spring, made, in particular, of micromachinable material. A gripper places the collet on an insertion guide on the vertex of a mock obelisk-shaped arbor for a first centring of the collet, this balance spring is allowed to slide under its own weight along the guide surmounting a frustoconical shank that completes the self-centring of the collet on the tool axis, and for holding this balance spring without stress on the shank, the mock arbor including a drive device cooperating with the inner contour of the collet for the relative driving in rotation thereof without slipping, a holding tool holds the outer coil of the balance spring, to measure the torque of the balance spring by rotating the main tool and/or the holding tool about the axis, without stressing the balance spring.

Abstract: A method for measuring the torque of a balance spring, made, in particular, of micromachinable material. A gripper places the collet on an insertion guide on the vertex of a mock obelisk-shaped arbor for a first centring of the collet, this balance spring is allowed to slide under its own weight along the guide surmounting a frustoconical shank that completes the self-centring of the collet on the tool axis, and for holding this balance spring without stress on the shank, the mock arbor including a drive device cooperating with the inner contour of the collet for the relative driving in rotation thereof without slipping, a holding tool holds the outer coil of the balance spring, to measure the torque of the balance spring by rotating the main tool and/or the holding tool about the axis, without stressing the balance spring.