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THE PART HOLDERS (MOVEMENT HOLDERS)

Part holder (movement holder) calibrated for fitting hands

What are part holders (movement holders) used for?

Part holders (movement holders) designate Bench supports intended to immobilize a Movement during assembly, disassembly, Regulation / Adjustment, and servicing operations. Their function is to provide the Horologist (watchmaker) with a stable support, at working height, which frees both hands for the use of tools and presents the piece in a position favourable to observation under a loupe or microscope, without the Movement resting on its other side. The diversity of Calibres handled and operations carried out at the Bench has given rise to a family of distinct instruments.

The Part holder (movement holder) most commonly found on the Bench takes the form of a short cylinder, made of synthetic material — Delrin being the most widespread — or of light Metal, whose upper face receives the Movement via its Case middle. Two main variants coexist: fixed-diameter movement holders, in which the Calibre fits into a Reaming cut to its exact size, and adjustable-clamping movement holders, whose movable jaws, controlled by a Screw, grip the Movement at its periphery. The former, more rigid, are preferred for precision operations where no deformation is acceptable; the latter, more versatile, cover, using a single tool, a wide range of diameters. The choice of a soft Material, notably Delrin, prevents any marking of the Main plate and preserves the lateral finish of the Movement.

The contact surfaces must remain clean, free of dust, residual Oil or chips liable to mark the part; Delrin models can simply be cleaned with alcohol or a soft brush.