The numerical simulation of machining, when dealing with flexible workpieces, still needs to be improved by the introduction of more accurate cutting force models. The aim of this paper is to propose a general method which is designed to generate transient cutting forces and severe cutting conditions including process damping to be able to set up cutting laws in these cases. In this first approach, the method is limited to orthogonal cutting. The method is based on a special design of a very simple "flexible workpiece" where slots have been introduced in the machined area to get an intermittent cutting. The exibility of the workpiece induces axial vibrations like it is done in vibration drilling and the presence of slots leads to cutting conditions similar to those of milling. The proposed testing device has been designed to be flexible along one degree of freedom, while the cutting tool is considered as rigid. This allows to generate cutting conditions where the axial depth of cut fluctuates as well as the contact between the cutting tool and the workpiece. The experimental setup allows the measurement of cutting forces and the simultaneous measurement of the relative tool/workpiece displacements. The measured signals and numerical interpretations of the machining operation allow to compare a proposed cutting law with the experimental results. The cutting law parameters can then be optimized, even when process damping occurs. The paper introduces a first application of the proposed method.