Abstract: A rotary indexing table having a generally circular top plate rotatably secured to a fixed base structure is disclosed. An outer race annular ring is connected to the top of the fixed base structure and extends radially over a central bore formed in the top face of the fixed based structure. A first ring of teeth is formed on the circular top plate. A second ring of teeth is formed on the outer race annular ring. Both the first and second rings of teeth face toward the central bore in the fixed base structure. A piston is slidably mounted in the central bore. The piston has a third ring of teeth aligned with the first ring of teeth and a fourth ring of teeth aligned with the second ring of teeth. A method of forming the third and fourth rings of teeth on the piston is also disclosed. The method includes mounting a sine block on a work table. Then fastening a rotary indexing table on the top of the sine block. Next, securing the piston to the top of the rotary indexing table.

Abstract: A precision rotary indexing fixture is disclosed of the type including a top plate adapted to have work pieces mounted thereon with the work plate indexed to any of a plurality of precision rotary positions. The precision locking of the top plate is achieved by serrated coupling rings, one mounted on the outer periphery of the top plate, the other mating ring mounted on a base structure. The top plate is locked in various index positions by the application of disc spring sets acting on the top plate through an annular piston and a set of bearing elements mounted in opposed grooves in the piston and a race ring mounted to the top plate. The fluid forces acting on the piston acts to release the locking pressure exerted by the disc spring sets and release the coupling serration engagement during indexing of the top plate.