Abstract: A computer generated tool path interference check including a method of checking for interference between a workpiece and a cutting tool during the numerical control machining of the workpiece by the cutter tool. Computer simulation is utilized to determine at least a portion of the workpiece that is desired to be checked for possible interference with the path of the cutter tool. The spatial relationship between the workpiece and the cutter tool during the machining are modelled as the relative positioning of the computerized images of the portion of the workpiece and the cutter tool, respectively. The relative positioning of the computerized images of the portion of the workpiece and the cutter tool are observed to check whether an interference will occur between the workpiece and the cutter tool during the machining.