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.
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.