Laser Cutter
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Running a single high-power pass concentrates too much heat in one spot, which causes excessive charring, wider kerf, and can start fires in combustible materials like wood. Multiple passes at lower power allow the material to cool between passes, resulting in cleaner cuts, tighter kerf, and less char. As a rule of thumb: if you can cut something in 2 passes at 100% power, try 3 passes at 75% and compare the cut quality.

Turn air assist off when cutting cast acrylic if you want a flame-polished, optically clear edge. Air assist on acrylic cools the melt too fast and creates a frosted, milky edge. For wood, leather, and most other materials, air assist on is almost always the right call — it blows smoke out of the beam path, prevents flare-ups, and keeps the lens clean.

Cast acrylic is made by pouring liquid acrylic into molds — it cuts and engraves beautifully on CO₂ lasers, leaving a flame-polished edge and bright white engraving. Extruded acrylic is made through a continuous process and is cheaper, but it's more prone to chipping, leaves a glossier (but less polished) cut edge, and doesn't engrave as brightly. For display pieces and signs, always use cast. For structural parts where appearance is secondary, extruded is fine.

Technically yes, but it's very difficult. Diode lasers operate at ~450nm (blue-violet wavelength), which acrylic transmits rather than absorbs — this is why it's so inefficient. Clear acrylic is especially difficult; black or very dark acrylic works somewhat better because the colorant absorbs the beam. You'll need many slow passes at full power, and the result won't compare to a CO₂ cut. If cutting acrylic is a primary use case, a CO₂ machine is the right tool.

In LightBurn, click the layer color chip on the left side panel to open Cut Settings. For diode lasers: Power (%) maps directly to the "Max Power %" field; Speed in mm/min maps to the "Speed" field. For CO₂ machines using mm/s natively, convert by dividing mm/min by 60. Set the number of passes in the "Passes" field. Air assist is controlled by checking "Air Assist" if your machine supports it, or manually via a relay connected to the Z axis output. Enable "Bi-directional Fill" for engrave passes to speed things up without affecting quality.

Never cut: PVC / vinyl (releases chlorine gas — extremely dangerous), polycarbonate (melts, doesn't cut, creates hazardous fumes), ABS plastic (toxic fumes, fire risk), fiberglass / carbon fiber (highly toxic particulates), chrome-tanned leather (toxic chromium compounds), coated metals without proper setup, and any material you can't positively identify. When in doubt, don't cut it. A good source for a safe materials list is the ATX Hackerspace materials guide, which is widely referenced in the maker community.