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1 November 2026 · 2 min read
How a desktop CNC router works, from drawing to cut
Six steps sit between an idea on screen and a groove in a board. Here's what each one does.
A CNC router is a cutting tool that a computer moves. The "CNC" stands for computer numerical control. On a desktop machine, the part that cuts is a spinning bit held in a router or spindle, and three motors move it left and right (X), front to back (Y), and up and down (Z).
The machine itself doesn't know what you want to make. It follows a list of moves. Most of the work for a beginner is in producing that list, and it happens in six steps.
1. Design (CAD)
You draw the part in a CAD program: the outline of a sign, the shape of a coaster, the pockets in a tray. Some makers ship their own. Carbide 3D includes Carbide Create with its machines, and Onefinity lists compatibility with Vectric, Carveco, Fusion 360, Easel and Carbide Create.
2. Toolpaths (CAM)
CAM software turns the drawing into the actual path the bit will follow. This is where you pick which bit to use, how deep each pass goes, and in what order the cuts happen.
3. G-code
The CAM program writes the result out as G-code, a plain text file of instructions. Wikipedia describes G-code as the language "that tells the motors where to move, how fast to move, and what path to follow". A line might say "move to X 100, Y 50 at this speed".
4. The sender
A program on your computer, called a sender, streams the G-code to the machine a few lines at a time and shows you where the job is up to. Sienci Labs names gSender as the sender most of its customers use; SainSmart lists UGS and Candle for its Genmitsu machines; Carbide 3D uses Carbide Motion.
5. The controller
The controller is the box of electronics on the machine. It reads each G-code move and works out the exact pulses each motor needs. Many hobby machines run firmware called GRBL or its newer relative grblHAL. GRBL's own description says it "accepts standards-compliant g-code" and plans speeds ahead so it can "look up to 16 motions into the future". There's more on this in GRBL, grblHAL and the controller box.
6. The machine
Finally the motors turn, the screws or belts move the axes, and the bit cuts. The parts of a typical desktop router look like this:
The gantry is the bridge that spans the work surface and carries the X axis. The Z axis hangs off the gantry and holds the router or spindle. The spoilboard is the board on top of the frame that the work sits on. Wikipedia sums up the arrangement: "A CNC wood router is a computer controlled machine to which the router or spindle mounts."
Where to go next
When you read a spec sheet, almost every line maps onto one of these parts. Work area, travel and footprint covers the sizes, leadscrew vs ballscrew covers how the axes move, and router or spindle covers the part that cuts.
Sources
Read on 1 November 2026. Quotes are copied from these pages.