Why Equip Turning Center With Y-axis? In a CNC turn mill, you generally have X & Z axes of the conventional lathe machine. The spindle doubles as C axis during turn milling operations. Milling is accomplished by rotating live tools that are mounted on the turret. In a turn mill center without a Y axis, you maybe only drill radial holes on the cylindrical surface of a shaft. If you want to perform any non radial operation on the cylindrical surface of the job (like hole drilling, slotting etc) you need to have a Y axis.