We previously proposed data-mining system to derive useful information from the data and attempt to determine the ball-nose end-milling conditions in a rapid prototype manufacturing system. Practical end-milling condition decision equations are derived to determine the end-milling conditions at each cluster by using response surface method. End-millings of hardened die steel JIS SKD61 (HRC53) and DH31S were carried out to investigate the practicability of derived mining conditions under contour line milling. As a result, our catalogmining system was found to be effective in selecting the endmilling conditions as the first trial condition. Catalog mining can derive indicative cutting conditions for unskilled engineers.