How to Make a PCB With a CNC Router

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  Key takeaways
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  Why engineers choose a CNC router PCB workflow
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  Design rules that fit a CNC router PCB
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  Hold the blank flat or nothing else works
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  Tooling: V-bits, end mills and drills
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  When a CNC router PCB is the wrong choice
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  Step by step: how to make a PCB with a CNC router
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  CNC router PCB milling vs chemical etching

A CNC router makes a PCB by cutting away the copper that should not be there. The tool follows a toolpath generated from your Gerber or DXF file, and the remaining copper becomes the traces and pads. There is no etchant, no UV exposure, and no photoresist to develop in a darkroom.

The obvious win is speed. A two-layer control board of 100 × 80 mm takes roughly 25 to 45 minutes of cutting on a hobby-class router, plus 10 minutes of setup. You can iterate on a layout three times in one day and hold the physical board in your hand.

The second win is material freedom. You can mill FR-4, but also Rogers laminates, aluminium-backed boards, and thin copper-clad sheets that a normal fab will not touch in small quantities. For RF test coupons and antenna prototypes this matters more than price.

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  No chemicalsNo ferric chloride, no disposal paperwork, no fume hood.
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  Fast iterationChange the layout, re-run the toolpath, cut again.
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  Odd laminatesPTFE, Rogers, aluminium core, and flexible copper-clad.
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  In-house dataDesign files never leave your building.

Set your CAD rules before you draw anything. For a typical 1 oz (0.035 mm) copper board with a 30° V-bit, use 0.3 mm minimum trace and 0.3 mm minimum gap. That combination is comfortable on almost any router with a stiff gantry. Push to 0.2 mm only if the machine has ball screws and the bed is genuinely flat.

Keep copper pour away from the board edge by at least 0.8 mm. The V-bit leaves a burr at the perimeter, and a pour that touches the edge will short against a metal fixture or a mounting screw. Add two 3 mm tooling holes outside the outline for dowel pins.

For double-sided boards, mirror the bottom layer and keep all vias as plain drilled holes. Do not design plated vias unless you own a plating line. Solder a short wire through each via, or place a via on both sides of a pad and bridge it with solder.

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  Trace and gap0.3 mm both is the safe default; 0.2 mm needs a rigid machine.
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  Copper to edge0.8 mm minimum, 1.5 mm if the fixture is metal.
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  PadsAdd 0.2 mm to the drill diameter for the annular ring.
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  Text1.0 mm stroke width minimum to stay legible after milling.

Copper-clad sheet is never as flat as it looks. A 1.6 mm FR-4 panel can bow 0.2 mm across 150 mm, which is six times the copper thickness. If you clamp the corners only, the middle lifts and the bit cuts air on one pass and buries itself on the next.

The fix is a spoilboard plus double-sided tape or a vacuum table. Tape the blank to a flat MDF or phenolic spoilboard, press it down, and let it sit for a few minutes. For repeated runs, cut a shallow pocket in the spoilboard so the blank drops in with 0.05 mm clearance.

Never clamp directly on the copper surface. The clamp marks become shorts and the pressure bows the board. Clamp on the spoilboard, not the workpiece.

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  Spoilboard firstFace it flat with a 20 mm fly cutter before each session.
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  Tape or vacuumNitto tape for one-offs, vacuum for repeat runs.
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  Pocket fixture0.05 mm clearance, 0.5 mm deep, for batch work.

Isolation routing uses a V-bit, usually 30° included angle with a 0.1 mm tip. The V shape gives you a cut width that grows with depth, so a 0.1 mm depth gives roughly 0.15 mm cut width and 0.2 mm depth gives about 0.25 mm. That is why depth control matters so much.

For clearing larger copper areas, switch to a 0.8 mm or 1.0 mm two-flute carbide end mill. Run it at 18,000 to 24,000 rpm and 300 to 500 mm/min in FR-4. Higher feed avoids the rubbing that dulls carbide in seconds. Add a finishing pass at 0.05 mm depth to clean the floor.

Drills are standard carbide PCB drills, 0.8 mm to 1.2 mm for through-hole parts, 0.6 mm for small vias. Run them at 15,000 to 20,000 rpm with a peck cycle of 0.3 mm per peck. Retract fully between pecks so chips clear the flutes. A clogged flute snaps a 0.6 mm drill instantly.

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  V-bit 30°0.1 mm tip, 0.05–0.12 mm depth for isolation.
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  End mill 0.8–1.0 mmFor copper clearing, 300–500 mm/min in FR-4.
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  Drills0.6–1.2 mm carbide, peck 0.3 mm, full retract.
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  SparesKeep five V-bits on hand; FR-4 abrasive glass dulls them fast.

Milling cannot produce plated through-holes. If your board has 200 vias and a fine-pitch BGA, hand-soldering wire through every via is not a plan. Send it to a fab. The same applies to any design with 0.15 mm traces or impedance-controlled differential pairs.

Solder mask is the second limit. You can apply UV-curable mask by hand, but registration over small pads is poor and the result looks nothing like a production board. If the board will be handled, sprayed, or used in a humid environment, mask matters.

The third limit is volume. Once you need 20 or more identical boards, the per-board time on a router stops making sense. A fab will deliver better registration, plated holes and mask for less total effort. Milling is a prototyping and repair tool, not a production line.

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  Fine pitch0.5 mm pitch and below needs a fab.
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  Many viasPlated holes are not available on a router.
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  Production volumeAbove roughly 20 boards, switch to a fab.