A professional who instructs workers in all operations concerned with assembly of watch movements. Responsibilities include:

• Conducts lectures on function of various parts and assemblies, and demonstrates assembly activities, such as overcoiling, putting-in-beat, truing ii, poising, colleting, staking, and vibrating. Instructs workers in handling of minute parts with loupe, microscope, and tweezers.
• May be designated according to assembly operation taught as hairspring instructor.