An innovative modeling approach to study the whirling motion of the lathe machine in the intermediate turning stage is presented by introducing the system excitation in the form of cutting forces between the cutting edge head and the workpiece. This involves nonhomogeneous boundary conditions with homogeneous equations. The mathematical modeling approach enabled us to solve the problem by modal analysis by transforming the problem into nonhomogeneous equations with homogenous boundary conditions. The proposed approach enables us to predict the whirling motion at different locations on the cutting edge-workpiece system.