The tool is held rigidly in a tool post (刀架)and moved at a constant rate along the axis of the bar(棒料) cutting away a layer of metal to form a cylinder or a surface of more complex profile(轮 廓). Figure 13-13.V-shaped ways guide carriage.The cutting tool is mounted on the carriage.The tool is held rigidly in a tool post （刀架） and moved at a constant rate along the axis of the bar (棒料）, cutting away a layer of metal to form a cylinder or a surface of more complex profile（轮 廓）