A copied laser setting is a guess about someone else's machine. A test grid turns it into evidence: a matrix of small patches, each burned with a different pair of values, on the same material you are going to sell. Ten minutes on scrap replaces an afternoon of ruined blanks.
1. Fix everything you are not testing
Set the focus, the lens, the air assist and the material batch you will use for the job, and keep them fixed for the whole grid. Place the grid where the job will run, not in a corner of the bed you never use. If one of these changes between cells, the grid measures that change instead of the setting.
2. Choose the axes and the range
Start with power against speed. Put the value you expect to work near the middle of the range, not at an edge, so the grid shows you what too little and too much look like. The free LightBurn test grid writes a native .lbrn2 with every cell on its own layer and its speed and power already set, so nothing has to be re-keyed. If you start from a row in the laser settings by material tables, its test-grid link opens a grid bracketed around that row: a row recorded at 40% and 800 mm/s opens a sweep from 20 to 60% power and 400 to 1200 mm/s.
3. Pick the file for your machine
LightBurn machines take the .lbrn2. Fiber and galvo machines running EZCAD take the EZCAD test card: a DXF with every cell on its own pen and a CSV listing each pen's speed, power, frequency and pulse width. For an xTool F2 Ultra, the MOPA sample card is a native .xcs with 30 cells sweeping power against frequency at 200 ns. Prefer to type the values yourself? The free material test grid SVG is a blank 5 by 4 grid labelled LOW to HIGH and FAST to SLOW.
4. Read the grid properly
Let the sample cool and wipe off any residue before judging it. The winning cell is rarely the darkest one. For an engrave, look for even tone, crisp edges and no brown halo of scorching around the mark. For a cut, look for the lowest power that goes cleanly through with the least charring on the back. For a mark on metal or a coating, look for a readable mark with no damage to the surface around it. Photograph the grid under even light so you can compare it with the next one.
5. Narrow it, then write it down
Run a second grid with smaller steps around the best cell. When you settle on a value, write it on the sample itself, keep the sample beside the machine, and save the values in the project file for that material. Re-test when you change the lens, the material supplier or the focus, or after maintenance on the laser.
Frequently asked questions: Settings
How many cells should a laser test grid have?
Enough to bracket the setting you expect, with room on both sides. The free sample LightBurn card is 4 by 6 cells, sweeping 10 to 100% power across and 100 to 400 mm/s down, and the EZCAD sample card has 30 pens. Start broad, then run a second, narrower grid around the best cell instead of one huge grid.
Why does the same setting look different on another board?
Because the material changed, not the laser. Plywood batches differ in glue and veneer, solid wood in density and moisture, coatings in thickness. A new lens, a different focus height or a dirty mirror moves the result as well. Re-run a small grid whenever the batch, the lens or the focus changes.
Should I test power and speed, or line interval?
Power against speed first: it decides whether the mark is there at all. For an engrave, then sweep line interval at the chosen power and speed, since it changes darkness and texture. For cut parts that have to fit together, test the kerf as well. The free generator sweeps power against speed, line interval or kerf offset.