CNC machining enables fine motion control of tools and workpieces simultaneously along multiple axes by a set of commands, simplifying manufacture of complex 3D components. Since the movements are not manually controlled, the operator does not have the tactile feedback based on which the cutting parameters can be fine-tuned to maintain and enhance the quality of cutting. One such aspect that is lost is the registration of the actual instant that the cutting tool makes contact with the workpiece. This can happen earlier or later than programmed due to variations in workpiece size and tool wear. This project uses commercially available sensors to analyse the change in sound and vibration from non-cutting movement to cutting operations, and applies MIR (Musical Information Retrieval) algorithms to determine the onset of cutting.