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Surface Plate Finisher

Inspect surfaces of stone plates.

What does a Surface Plate Finisher do?

Inspects surface of stone plates to determine areas requiring lapping, and levels stone surface to specified tolerance for use as surface plates: Builds bed of timbers on floor beneath head of lapping machine. Positions stone on timbers, using hoist. Aligns stone with arm of lapping machine and levels stone on timbers, using wedges, blocks, and spirit level. Moves straightedge over stone to detect uneven areas on stone surface. Wets stone surface, using hose, and applies abrasive to stone, using brush. Selects lapping block according to uniformity of stone surface or step in finishing process. Lifts block onto stone, using hoist. Secures block to arm of lapping machine, using wrench. Starts machine and presses buttons to guide spinning block over uneven areas of stone surface. Moves tolerance dial indicator through specified patterns on stone and observes dial to detect tolerance deviations. Changes lapping blocks according to readings from tolerance dial indicator and laps surface down to level finish. Laps stone by hand to level surface to specified tolerance. Sights through convex lens of collimator at specified positions on stone surface to determine whether surface plate has been finished within prescribed limitations of accuracy and determine tolerance deviation of plate’s surface. Prepares graph of collimator readings, indicating tolerance deviation at any point on surface of plate. Drills adapter holes in surface plate to facilitate attachment of measuring instruments, using diamond drill.