Motion is controlling quantity of} axes, usually high precision machining minimal of|no less than} two , and a software spindle that moves in the Z . The position of the software is driven by direct-drive stepper motors or servo motors to provide highly correct movements, or in older designs, motors by way of a sequence of step-down gears. Open-loop control works as long as|so lengthy as} the forces are kept sufficiently small and speeds usually are not too nice. On commercial metalworking machines, closed-loop controls are standard and required to provide the accuracy, velocity, and repeatability demanded. In CNC machining, start-up prices are mainly linked to course of planning.