The machine-tool interactions are studied with respect to the chip/tool friction boundary on the tool-piece rake face. The grazing motions with this chip/tool friction boundary are the focus of the study and how the effects are identified quantitatively. This study considers the transient motion of the machine-tool and will provide a framework for prediction of such grazing motions. The proposed study will include prediction through a range of excitation and system parameters. The significance of this lay within the application and the general approach to the definition of grazing via discontinuous systems theory.