CNC (Computer Numerical Control) is a mill that can be instructed what to do by a computer program. Consisting of 3 main components. First, is the mill which has a rotating spindle that can run any number of cutting tools including fly cutters, drills and other examples of end mills. It’s a drill like tool which unlike a drill bit can cut sideways or up (z axis) and down (Y axis). It has a table that moves sideways (x axis). All the (x), (y) and (z) movements are driven by little stepper motors which can be controlled with very tiny and precise increments.
By combining x, y and z movements all at the same time, extremely complex parts can be produced with tolerances in the thousands of an inch range. Additionally there’s a much larger motor that’s responsible for the spindle. All these motors can be made to run slower, faster, backwards, just in any way. There are various add-ons to the machines such as lubricants. You can also control the tool holders by adding a pneumatic gizmo which helps you change tools relatively quickly without tightening or untightening the drawbar which holds tools in this spindle. Addition of enclosures is possible so that the tool won’t splatter all over. You can add a stand, fourth axis tray that accumulates all the waste when you cut. Inside the mill is an electronic control system which tells all four motors what to do controlling speed, direction and movement of the spindle.