CNC routers usually are industrial grade machinery. Smaller models and DIY kits are readily available for hobbyists and home woodworkers, but these relatively cheap units will still break nearly all hobby budgets. These machines are made for business.
Fundamentally, a CNC router is a spinning, high-speed bit placed to a framework which allows it to move along all three axes, making two- or three-dimensional cuts all under the control of a computer program. That program works from a CAD drawing created on the screen.
The basis for the machine is really a large, flat bed so as to hold down the material being shaped. The hold-down mechanisms vary, but the most common is tiny holes in the bed and vacuum suction from below. This not only holds the sheet material in place, but also continues to hold even small pieces after they have been cut.
Along the long edges of the bed is mounted a track. Along these tracks ride a higher beam that will traverse the bed, providing movement along the X-axis. Mounted on this beam and traveling along it is a platform which moves along the Y-axis. On this platform is installed the cutting tool, the router. This platform could also raise and lower, enabling movement along the Z-axis.
Servo motors drive the beam to and fro along the X-axis, move the platform forward and back along the Y-axis, and raise and lower the router platform alongside the Z-axis. Control of the servo motors is given by CNC instructions from the computer. In a different design, the bed itself shifts in the X and Y directions, while the router moves changes up and down.
A Computer Aided Design (CAD) program makes it possible for one to develop a three-dimensional drawing on the screen. Using the drawing, the CAD program then develops a file of CNC (Computer Numerical Control) instructions. These instructions are specifically for positioning the beam and platform, using the servo motors. This file is then used to control the actual operation of the equipment, making all the necessary cuts and shaping.
The effect of all this technology is a machine which will make incredibly specific measurements and cuts. Some sort of tolerances are as small as 1/1000th inch. By reusing the CNC file, you possibly can produce the same results every time, and, apart from the placement of the sheet goods on the bed, it is all automated.
It is really wonderful how the technologies shape the world today. With just a click of a finger, everything becomes possible. Computer, CAD software, and CNC routers are only some of the major inventions of the world nowadays.
Accuracy, repeatability and automation are the qualities of a CNC router that make it so popular among manufacturers. It is rarely found in home workshops, though it is what every home woodworker would love to have. Mostly, however, businesses small and large are formed around one or more CNC routers.