Balance scale
The balance scale serves to compare the balance in pocket watches and consists of two precisely sanded and hardened steel cutting, which are mounted on brass feet. They can be moved in prism by means of left and legal thread. The unrest must be in balance in every position, so it must not be undercare. The focus of the rotation must not be outside the axis of rotation. Such a mistake can be localized if you put the rest of the unrest on the cutting of the balance scale and move the balance.