A professional who tends truing machine that mills and recuts surfaces of metal lap used in grinding and polishing eyeglass lenses to specified curvature. Respnsibilities include:

• Holds lap against rotating brush to remove marks indicating number of times lap was used.
• Set scale indicators of truing machine, according to dioptric power indicated by numbers on lap, and clamps lap in chuck of machine.
• Starts machine and positions cutting blade against surface of lap, or engages automatic feed mechanism which reciprocates lap against cutting blade to shave and true surface of lap.
• Removes lap from machine chuck, and measures it for conformance to specifications, using template.
• Grooves surface of lap to retain abrasive on surface edges of lap, by hand or machine, to remove roughness caused by cutting, truing I, and grooving operations.
• Occasionally sharpens cutting blade, using grinder.