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Using a CNC Router

A DIYer demonstrates how to use a Computer Numerically Controlled router.

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how to use computer numerically controlled router

CNC stands for Computer Numerically Controlled. That means that the tool is controlled by a steady stream of X, Y, and Z coordinates that come from a computer.

The tool in this case is a standard 3-14" HP woodworking router. The router is mounted into the CNC fixture. The X-axis is left and right. The Y-axis is the space going back and forth on the table. The Z-axis is up and down. The computer sends coordinates to the motors on the fixture and moves the router in all 3 axes simultaneously. The motors also send information back to the computer so the tool knows where it is at all times.

CNC routers are used in many different industries. In woodworking, CNC routers can be used to make signs, chair backs, or to carve intricate designs, as on this box.

The box begins as a drawing in a CAD-CAM package (CAD stands for Computer Aided Design). CAD is the drawing, which can be drawn on the screen or imported from another program. CAM -- Computer-Aided Machining -- is the tool path information.

The box is made in three tool paths. The first path trims the top lip of the box. The second path hollows out the center of the box in three passes of increasing depth. Each of the three passes cuts a 1/2" depth into the material at a rate of 3" per second. The third tool path cuts the outside perimeter of the box. This path is made in four passes, due to the increased depth of the cut. (The CNC router is precise to within a few 1000ths of an inch.)

Some material is left at the base of the box to hold it in position while it’s being cut. This can be removed with a band saw.

The lid for the box has a 3D profile. To program the lid of the box in the CNC router, scan a photo into the computer.

Use a 3D modeling program to create an oval the same size as the box. Then, build up the material on top of the box and apply a relief carving of the picture to create a 3D cameo effect with the picture. A digital photo can also be used for this process.

For the lid, an 1/8" ball nose bit with a large cutting area is used in the router. It is a solid carbide tip that has a slight taper to give it strength.

The CNC router can be used in several materials, including hard or soft wood, metal, and plastics.

It takes about 15 minutes to go from a photograph to a completed 3 dimensional carving.