A deficiency in computer controlled machining, especially relevant to large castings, is that no equipment exists to reveal material defects which become exposed during machining. These are discovered only at final inspection when faulty items are often scrapped, wasting machine time, energy and raw materials. This project addresses the deficiency. A sensitive in-situ defect detector will be programmed to scan critical machined surfaces for defects exposed or created during machining, reporting them and terminating the cycle if necessary. Research and development will refine detector principles and design mechanical and electronic assemblies. New software will operate an interactive telemetry link between a control panel and the in-situ defect detector and analyse and display defect information. Pre - competitive prototype units will be built for evaluation by manufacturing industry.