ECCENTRIC

The term eccentric has, in horology, both an adjectival and a nominal value. As an adjective, it describes something that is off-center, which does not share the same center as another element. As a noun, an Eccentric is a cylindrical part whose geometric center is intentionally offset from its axis of rotation. When turning, this Eccentric displaces its edge by a fixed amount and behaves like a small Cam: it usually serves as an adjustable stop for making fine adjustments. The most common example is the Eccentric of the Regulator, which allows precise adjustment of the position of the holder for the Stud (hairspring stud) or of the regulator when setting the Guide mark of the regulating organ. Eccentrics are also found for adjusting play, lever positions, or safety devices. By rotating the Eccentric, the Horologist (watchmaker) achieves a micrometric displacement, essential for the delicate adjustments of the Movement. Simple and ingenious, it embodies the principle of Regulation / Adjustment by off-centering.