SET

In horology, Set is the space intentionally provided between two components to allow one of them to move freely, without excessive friction or jamming. Essential to the proper functioning of the Movement, it compensates for thermal expansion, manufacturing tolerances, and the thickness of the film of Lubricant. In particular, a distinction is made between axial Set, or Shake (play), which corresponds to the slight longitudinal movement allowed to a pivot between its two jewels or bearings; radial or diametral Set, provided between a pivot and its Bearing; and gear tooth Set, or root Set, which separates the tip of a wheel’s tooth from the root of the mating tooth space in a Gear. Too little set causes hard spots, premature wear, or even jamming under the effect of expansion; excessive set generates vibrations, shocks, meshing defects, and loss of precision. Its regulation / adjustment is therefore a matter of compromise measured with feeler gauges or suitable dial indicators. The joint mastery of axial and radial sets, at every stage of the train (wheel train), is one of the hallmarks of the careful work of the horologist (watchmaker).