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8CNC Router Essentials

1 : CNC Basics

Machine mechanics

Basic CNC (computer numerical controlled) routers operate on three axes: X, Y, and Z, Image 1.1. Think back to your days of graphing in math class. The X and Y axes move le to right and front to back, while the Z axis is vertical. The machine can move in all three directions at one time, which allows it to cut complex shapes as easily as simple shapes. Most CNC routers use an industrial high-speed spindle, although some CNCs use woodworking-style router motors to hold the bit or cuing tool, Images 1.2. The main differences are spindles run quieter and are more accurate than woodworking routers, plus a spindle’s bearings last several times longer than those in a woodworking router,

but a spindle costs several times the price of a similarly sized router. Some CNC tools allow you to start with a router motor and later upgrade to a spindle. The bed or deck of a CNC machine may be metal, plastic, or plywood, and is oen covered with a spoilboard, Image 1.3. The spoilboard is usually a sheet of MDF or plywood. It is a consumable item, since many projects require you to cut completely through the project material and slightly into the spoilboard. Over time the spoilboard will become grooved, but you can renew it by routing the surface flat. When the spoilboard becomes too thin, it can be replaced, or a new one can be glued on top of the old one.

Image 1.1: Three-axis CNC machines move in three directions. The Z axis controls vertical movement. The X and Y axes control the left to right, and front to back movement. The X and Y are reversed on some machines.

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