The amazing CNC machine

An oversimplified guide to a highly useful tool.

A LOT OF people know what a CNC machine is. But for those who nod and hope the subject changes, a CNC machine is a computer-driven cutting tool. You can use a CNC to carve out ornate inlays in furniture, template a jig, or even make your own guitar. CNC stands for computer numerical control, which basically means that you input the plans (in the form of a vector or line drawing) and the machine cuts them. Because the process is computerised, you get the same results every time. And they’re always perfect.

CNCS can get expensive. Woodworker Ben Aroh (pictured), started out with a small, basic machine that cost R75 000. A year later, he bought one for R225 000 and now he’s considering upgrading to a R600 000 option. The real difference is in the router bit. The cheaper the CNC, the cheaper and less powerful the router.

Industrial CNCS use beefy routers called spindles. They’re much quieter and have five to ten times the power. The bits last longer and you get a cleaner, much faster cut. Just be sure that the bit you’re using is optimised for your materials – wood, plastic, aluminium, whatnot. Also pay attention to the types of bits. Up-cut bits expel shavings upward, leaving a smooth finish on the bottom of the material. Down-cut bits do the opposite and compression bits do both, leaving you with a smooth cut on the top and bottom. And then there’s the number of flutes, or cutting edges, that spiral down the bit. The more you see, the smoother your cut will be.

When is a CNC worth buying? If you’re making a lot of a particular thing. Less expensive alternative: find a machine for hire at a local maker space or cabinet maker’s.