Method for manufacturing a sprung balance oscillator for high torque variation balance springs

Abstract

A method for manufacturing an oscillator for a timepiece made from a balance and a balance spring, the method including measuring the average moment of inertia of a batch of balances; providing pinned up balance springs, the balance springs having an excess number of coils forming up to three more turns than the final number of coils; making a first predetermined external cut of the balance springs over a length of one to two coils, then measuring the torque of the balance springs and sorting them according to the value of the measured torque; assembling the balance springs, whose measured torque corresponds to the balances, are assembled to form an oscillator with an intermediate frequency and to determine the length to be cut to achieve the desired oscillation frequency; making a second external cut of the balance springs selected to achieve both the desired oscillation frequency and a target value.

Dependencies are inferred from the claim text.