Mounting a Diode Laser Module on Your CNC Router: Dual-Use Gantry Conversion

If you own a Wolfpawn 4040 Pro or similar GRBL-based CNC router and only occasionally need to engrave or mark a part — a logo on a jig, an alignment mark, a shallow decorative pass on a sign you just routed — buying and setting up a dedicated machine like the Longer Ray5 20W for every small job is overkill. This guide covers physically mounting a standalone diode laser module onto your CNC router's gantry as a second tool, so you can swap between spindle and laser without moving the workpiece or leaving the machine. This is a hardware and firmware conversion, distinct from simply running your CNC and a separate laser as two machines in a shared workflow — here the laser lives on the same gantry, on demand.

Choosing a Module

Module PowerGood ForTypical Cost 2–5WLight engraving on wood, marking on anodized aluminum, paper/cardboard cutting$40–$90 10WDeeper engraving, cutting thin plywood (1/8") in multiple passes$120–$180 20W+Approaching dedicated-laser territory — at this point weigh whether a standalone Ray5 makes more sense given enclosure and safety requirements$200+

Stick to a module with a TTL/PWM control input rather than a simple on/off switch — you need variable power control from GRBL to get usable grayscale engraving and clean cut edges.

Mounting and Wiring

Design or download a mounting bracket sized for your gantry's Z-axis carriage. Most accessory laser modules use a standard clamp diameter; a 3D printed PETG or ABS bracket works fine since it's not load-bearing like a spindle mount.
Position the bracket so the laser's focal point sits at a known, fixed offset from your spindle's tool tip — you'll use this offset in your CAM software or post-processor to compensate Z height when switching tools.
Wire the module's control input to a spare PWM-capable pin on your controller board. On Woodpecker/GRBL 1.1 boards this is usually the same pin used for spindle speed control, since GRBL's laser mode repurposes it.
Wire the module's power leads to a separate switched 12V or 24V supply — do not tap this off the spindle's VFD output, which is a different voltage and control scheme entirely.
In your GRBL settings, set $32=1 to enable laser mode. This changes how GRBL interprets S-values (power) during moves and disables the spindle-specific dwell-on-start behavior that would otherwise burn a hole at the start of every cut.
Add a physical toggle or relay so the laser is only powered when you're actively in a laser job — you do not want 12V live to the module during normal routing operations.

Test Settings

MaterialModule PowerSpeedPasses 1/8" plywood (engrave)60–70%1500–2000mm/min1 1/8" plywood (cut, 10W module)100%150–250mm/min3–5 Anodized aluminum (mark only)80–100%800–1200mm/min1–2 Cardboard/paper30–50%2000–3000mm/min1

These are starting points, not gospel — run a test grid on scrap the same way you would when dialing in any laser, since module output and lens focus vary between units.

Safety

This is the part that's easy to skip and shouldn't be. A dedicated diode laser like the Ray5 comes with a frame and, in many configurations, shielding around the beam path; an accessory module bolted onto an open CNC gantry has none of that. You are adding a Class 4 laser hazard to a machine with no enclosure. Wear laser safety glasses rated for the module's wavelength (most cheap blue diode modules are 445–450nm) any time the laser is powered, even briefly for focus checks — reflections off metal workholding or the router's own aluminum extrusions can send stray beam in unexpected directions. Add a hardware interlock if you can: a limit switch or relay that only allows the laser power supply to energize when a physical guard or enclosure panel is in place, and never rely on software alone to keep the laser off during routing operations. Keep the room ventilated for fumes just as you would with a dedicated laser, and never run the spindle and laser module powered simultaneously — there's no scenario where you need both live at once, and it removes any ambiguity about what the machine is doing.

Once it's set up, tool-changing between spindle and laser is just a matter of loading the right G-code file with the right Z offset baked in. It won't replace a dedicated laser cutter for serious engraving work, but for the occasional mark or light engrave on a part you're already machining, having both tools live on one gantry saves a lot of back-and-forth.

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