Abstract: A tool may be used to form an engine cylinder bore in a compacted graphite iron workpiece using helical interpolation. The tool may be rotated about a first axis while orbiting about a second axis that is parallel to the first axis. While rotating and orbiting, the tool may be advanced into the workpiece. This helical interpolation may be used to successively engage cutting or honing elements of the tool with the workpiece. The elements may thereby be permitted to cool between each successive engagement, which may reduce wear on the tool. Various operating parameters associated with the process may have certain relationships that may be exploited in certain ways to obtain ideal results. For instance, a helical interpolation process may be used to perform an act of rough cutting on the workpiece and finish honing on the workpiece, without having to perform an intermediary step of semi-finish boring.