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Creative Hardware

CNC Routing: Getting Started

From a drawing to a cut part: what a CNC router actually does, the three pieces of software in every workflow, how to hold your material down, and why your first cut should be air.

4 min read

A 3D printer adds material and forgives mistakes. A CNC router removes material with a spinning bit at 18,000 RPM, and mistakes make noise, snap tooling, and occasionally throw your workpiece across the room. It’s not dangerous if you understand the workflow, and this guide covers that workflow rather than any one machine.

1. Three programs, not one

Every CNC job passes through three stages, and beginners get stuck because tutorials blur them together.

  1. CAD — the shape. Your design: vectors for 2D cutting, a model for 3D carving. Fusion 360, Onshape, Illustrator, Inkscape or the drawing tools built into your CAM software all work.
  2. CAM — the strategy. Where the bit goes, how deep each pass cuts, how fast it moves, which direction it travels. This is the step that decides whether your part comes out clean, and it’s where CNC actually lives. Output is G-code.
  3. The controller — the run. Software that streams G-code to the machine and lets you jog it, set zero and pause. Common ones are gSender, Universal Gcode Sender, Carbide Motion or the vendor’s own.

If you’re confused about “what program do I use,” the answer is all three, in that order.

2. Workholding comes before everything

The single most common beginner failure is not a bad toolpath. It’s the material moving.

Options, from simplest up: clamps at the edges (free, but they’re in the bit’s way), double-sided tape plus a flat spoilboard (works far better than it sounds for thin sheet), screws through waste areas into the spoilboard (best when you can afford the holes), and painter’s tape and superglue — tape the workpiece, tape the bed, glue the tapes together; it holds surprisingly hard and peels off cleanly.

You also want a spoilboard: a sacrificial flat sheet on the bed that the bit can cut a hair into on through-cuts, without touching the machine.

3. One bit to start

Ignore the bit assortment for now. A 1/8” (3mm) two-flute upcut end mill will do nearly everything you need to learn on. Upcut pulls chips up and out of the cut, which keeps the bit cool and clean, at the cost of some fuzz on the top edge of wood.

Add a 60-degree V-bit when you want engraved lettering, and a downcut bit when top-edge finish matters more than chip clearing. Three bits cover most of a first year.

4. Feeds and speeds, in plain terms

Three numbers:

  • Spindle RPM — how fast the bit spins
  • Feed rate — how fast the machine moves through the material
  • Depth of cut — how much material per pass

The instinct is to go slow and shallow to be safe. Going too slow is its own failure: the bit rubs instead of cutting, heats up, burns the wood and dulls the edge. You want it cutting chips, not dust.

Start with your bit manufacturer’s chart for your material. They publish these, and they’re better than anything you’ll guess. A reasonable first rule for a hobby machine in softwood or plywood with a 1/8” bit: depth per pass no deeper than the bit’s diameter. Listen to the machine. A steady cutting sound is right; screeching or chattering means change something.

5. Zero, then cut air

Setting zero tells the machine where your material is. Jog the bit to the corner of the workpiece, set X and Y to zero there, then lower until the tip just touches the surface (a sheet of paper as a feeler works) and zero Z.

Then, before every job as a beginner: raise Z by an inch and run the whole program in the air. Watch the bit trace your part above the material. You’ll catch a wrong zero, a mirrored design or a plunge through your clamp while it costs nothing. Experienced operators still do this on unfamiliar jobs.

6. A realistic first project

Make a name sign or a simple bracket from 1/2” plywood: a pocket cut, a profile cut around the outside, and tabs — small uncut bridges that keep the part attached until you cut it free by hand. Without tabs, the part comes loose on the final pass and gets thrown.

That project teaches zeroing, workholding, two toolpath types and tabs in one sitting. Do it three times before designing anything complicated.

Safety, briefly

Eye protection always. Hearing protection: routers are loud. No loose sleeves or long hair near the spindle. Keep a hand on the feed hold or the power switch on the first run of any new job. Wood dust is a respiratory hazard, so run dust collection or a mask, and be aware that MDF dust is especially unpleasant.

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