STONE CUTTING (LAPPING)

Stone cutting (lapping) is a surface machining operation, as well as its result, which consists of grinding and then To polish a part using a Disc rotating — called a lapping wheel — made of metal or covered with an Abrasive (abrasive paper, diamond paste, abrasive solution), mounted on a dedicated machine, the lapping lathe. The term comes from the vocabulary of the lapidary, a craftsman who cuts precious stones, whose grinding technique has been transposed to the working of metals. Depending on the grain size of the abrasive and the geometry of the disc used, stone cutting (lapping) allows both roughing out and flattening a surface — flat lapping — and giving it a regular curve — domed lapping —, gradually refining it to a state close to polished. In watchmaking, it is used in the preparation and leveling of components such as the bridges, the Main plate or certain External parts (case, dial, hands) componentsExternal parts (case, dial, hands), and frequently precedes decorations such as Beveling / Angling, Circular graining or Satin finish. Mastering it requires rigorous control of flatness, applied pressure, and the grit used: a gradual progression from coarse to fine grit prevents deep scratches and ensures a homogeneous surface, a condition for a refined finish.