As the feed rate of cutting tools is influenced by the quality of NC programs, this causes two problems when cutting freeform surfaces using NC machine tools, one is the feed rate does not reach the specified value, and the other is the quality of the machined surface decreases due to the large acceleration and deceleration of the control axes. One reason for these problems is that the method to generate cutter location data does not take into consideration the sampling time of the NC controller. To improve these problems, the approximation of offset curves with a series of circular arcs has generally been proposed. But conventionally, circular arc interpolation algorithms are complicated and not rational. So, in this study, we proposed two simple NC program generation methods. (1) Approximate the offset form with circular arcs based on the location of the center of curvature. (2) Make the distance between the cutter location points of the NC data an integral multiple of the "feed rate command F × sampling time T". We also confirm the effectiveness of the proposed methods by simulations and experiments.