In order to design and improve a new machine tool, there is a need for a better understanding of the optimal cutting conditions under which a machine tool can be used most efficiently without deterioration of the machined surface can be determined from the stability analysis based on the dynamic characteristics of the cutting process and of the machine tool structure. In this paper, the computer programs were developed to predict the optimal cutting conditions. The results of the theoretical stability analysis are presented in the form of undeformed chip area-rotational speed in the stability chart. The theoretical optimal cutting conditions in the stability chart were verified through the analysis of the peak power of spectrum signals of the measured cutting forces in the frequency domains.