Device for assembling and adjusting a balance spring

A device for assembling and adjusting a balance spring intended to cooperate with a terminal coil of a balance spring whereof the inner end is secured to a balance-staff of a balance, said balance-staff being pivoted in a balance-cock, the device including

• a base intended to be assembled to the balance-cock with an adjustable angular orientation, and comprising a substantially cylindrical support surface with a radius substantially equal to the radius of the terminal coil, and a support sole adjacent to the support surface, said support surface and said support sole defining a service position of the terminal coil,
• a first arm extending from said base and supporting a locking organ for locking the terminal coil arranged to keep the terminal coil bearing against the support surface,
• said device further including
• a second arm extending from said base and supporting a sabot able to be arranged at a predefined distance from said support surface to cooperate with the terminal coil, and
• a control organ movable between first and second configurations and arranged such that it is able to act on the second arm and deform it elastically to move the sabot in reference to said base, said first and second configurations of said control organ being associated, respectively, with a first position of said second arm, in which said sabot is situated at a distance from said support surface equal to said predefined distance, and with a second position of said second arm, in which said sabot is situated at a distance from said support surface greater than the predefined distance.