Two types of tool path generation algorithm are proposed for the machining of a rotating workpiece with the free-formed surface using a cylindrical tool. The first algorithm is applied to the free-formed surface formed on a hard model. In this case, the hard model is measured by a cylindrical probe contacting its side surface. The tool path is calculated from the locus of the cylindrical probe center. The second algorithm to generate the tool path is developed for the free-formed surface defined by a set of numerical data. On each calculating system, the cutter interference and the minimum radius of curvature of the free-formed surface's projection curves are calculated. The accuracy of calculation on the radius of curvature is also discussed. A golf club is used as an example of the free-formed surface.