In this paper, the influence of guide mechanism on the contouring errors of circular interpolation motion in the NC machine tools is analyzed theoretically. In order to analyze the errors at the quadrant changes, a dynamical model of a feed drive is proposed. The model can deal with linear rolling guide way, sliding guide way and sliding guide way with influence of wiper seal. By using the model the equations that describe motion of ballscrew or motion of slide table after the quadrant changing position are derived. Calculating the motion, the relation between characteristics of guide mechanism and contouring errors such as stick motion or lost motion is clarified. Some motion tests are conducted, and the measured motions coincide with the calculated motions fairly well.
