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Run a material test grid before every new material

The single most useful habit for laser users. Burn a small grid of power and speed combinations on an offcut, then pick the square that looks right — instead of guessing and wasting a full sheet.

Updated 4 October 2026 · Beginner · Any laser (diode, CO2 or fibre)

Fingertips holding thin plywood discs cut with patterns of circular holes, with more pieces on the bench
Thin plywood components fresh off a laser cutter Photo: Jared Tarbell from Awesometown, United States of America, CC BY 2.0

Why bother?

Two sheets of “3mm plywood” from different suppliers can behave completely differently. Glue layers, moisture, species and even the batch change how much power it takes to cut through or to engrave a clean, dark mark. Settings from a forum post or a different machine are only a starting point — a test grid tells you what your machine does with your sheet.

What you need

  • An offcut of the exact material, at least 100 × 100 mm
  • Your laser’s software (most include a built-in test-grid or “material test” generator — xTool Creative Space, LightBurn and others do)
  • Masking tape or the sheet’s own protective film, if you normally use it
  • The safety basics in place: extraction running, glasses on if your machine is open-frame, and you standing by the machine

Steps

  1. Focus correctly for the material’s thickness, exactly as you will for the real job. A test at the wrong focus tells you nothing.
  2. Generate a grid of small squares — for example five power levels across and five speeds down. For engraving tests, fill each square; for cutting tests, use small circles or squares and a separate row for the number of passes.
  3. Label the grid with the power and speed values (most generators engrave the labels for you).
  4. Run it and stay with the machine. Watch for flaming at the high-power, slow-speed corner; that tells you to stop going in that direction.
  5. Inspect the result. For engraving, look for the evenness and darkness you want without heavy charring. For cutting, press each piece gently — it should drop out cleanly without being forced.
  6. Write it down. Keep a notebook or a saved preset with the material, supplier, thickness, focus, power, speed, passes and whether air assist was on.

Reading the grid

  • Too light / not through: increase power or slow down — or add a pass for cuts.
  • Dark brown halo, heavy charring: too much energy; speed up, reduce power, or turn on air assist.
  • Engraving looks stripy: try a higher LPI (smaller line interval) or check that the material is flat.
  • Cut is through on one side of the bed only: the bed may not be level, or the material is warped — weigh it down or use pins.

Make it a reference card

Once you have a grid you like, cut it out and keep it with the material stock. Over time you build a physical library of reference squares that is faster to consult than any spreadsheet.