Abstract: A computerized method and apparatus for high pressure grit or sand blasting comprises an upright cabinet through which work pieces, supported by a roller conveyor, can be disposed for blasting. An elongated actuator assembly horizontally extending across the enclosure interior comprises a pair of rigid, spaced-apart, rails upon which a displaceable carriage can move. The carriage supports a sand blasting head and nozzle. An internal tape within the actuator assembly moves the carriage. Tape condition is monitored by software in response to a magnetic sender driven by the tape idler pulley and an adjacent Hall effect sensor that picks up timed pulses. The actuator assembly is braced by buffer wheel assemblies at each end, in contact with vertical guide rails at each cabinet interior end. The hose-fed sand blasting head secured to the carriage directs sand or towards a target work piece be processed.