Diode Troubleshooting
Common diode issues and the fastest fixes. Most problems trace to focus, lens cleanliness, or settings, exactly the same as fiber and CO2.
Engrave is weak / barely visible
- Focus drift. Re-focus. (90% of cases.)
- Lens contamination. Inspect lens; clean if visible residue.
- Power scaled accidentally low in Lightburn, check layer settings.
- Speed too high: slower is more visible.
- Diode head aging: gradual power loss over years.
Engrave is too aggressive / burning through
- Speed too low: increase mm/min.
- Power too high: drop 5-10%.
- Multiple passes accidentally enabled: check Number of Passes in layer settings.
Skipped lines / inconsistent engrave
- Belt tension loose: tighten timing belts.
- Speed too high for diode mechanics: drop speed; diode steppers can skip at high mm/min.
- USB cable interference: try a shielded USB cable, especially on long runs.
- Diode firing inconsistently: check controller / firmware.
Engrave is mirrored / rotated
- Wrong Job Origin dot: check 9-dot selector.
- Bed orientation in Device Settings doesn't match physical machine: flip X or Y axis.
- Origin direction incorrect: verify homing direction.
Lightburn won't connect to diode
- Wrong COM port: check Windows Device Manager; try other ports.
- Wrong baud rate: most diodes use 115200; some Sculpfun/Atomstack use 9600.
- USB cable issue: try a different cable (cheap cables fail).
- Driver problem: install / reinstall the CH340/CP2102 driver.
- Power-cycle: the diode AND the computer.
- Other software hogging the COM port: close any other software that might be connected (xTool Creative Space, Sculpfun apps, etc.).
Photo engrave is muddy / bad
- Source image levels not stretched, re-edit in Photoshop.
- Wrong dither: Stucki for wood, Jarvis for slate.
- DPI too low: 254 DPI minimum on diode for photos.
- Surface too reflective: diode can't dither cleanly on polished surfaces.
Cuts won't go through
- Insufficient passes: diode cuts need many more passes than CO2 for the same depth.
- Focus drift between passes: for fixed-focus heads, the working surface drops as material is removed; manually re-focus or accept slower cuts.
- Wrong material color: diode can't cut clear acrylic; verify substrate.
- Lens contamination: clean.
- Air assist absent: adding aftermarket air assist transforms cut quality and depth.
Smoke / soot streaks across engrave
- No air assist: install aftermarket kit.
- Mask first: painter's tape catches smoke residue.
- Direction of fume extraction: extraction should be running while the laser is firing.
- Engraving over an already-burnt area: clear smoke between passes.
Diode head clicks / ticks
- Belt skipping: adjust tension.
- Stepper motor losing steps: too fast for diode hardware. Drop speed.
- Loose mounting hardware: tighten.
Laser dot is faint or distorted
- Lens contamination: clean.
- Lens damaged: replace.
- Diode head failing: power loss precedes complete failure.
Material burns at one corner of the bed but not another
- Bed not level: corners differ in distance from head. Adjust bed leveling screws.
- Frame warping: open-frame diodes can flex over time. Check fasteners.
- Belt tension uneven: adjust.
Engrave time is way longer than Lightburn estimated
- Travel speed too low: increase travel/jump speed in Device Settings.
- Optimization disabled: turn on; check "Reduce travel moves."
- Many disconnected shapes: combine where possible.