Setting Up a Power and Speed Test Grid in LightBurn
Why You Need a Test Grid
Every material sheet is different — even two pieces of "3mm basswood" from the same store can have different moisture content, resin distribution, or surface treatment. Running a power/speed matrix on scrap before committing to your actual job saves material, time, and frustration.
LightBurn makes this easy with the Material Test feature. Here is the full process.
Setting Up the Array
Open LightBurn. Go to Laser Tools → Material Test (or use the Array workflow manually).
Built-in Material Test Generator
File → Material Test Generator — opens a dialog that builds the grid automatically.
Set:
- Min power and Max power — the range to test across columns
- Min speed and Max speed — the range to test across rows
- Shape size — each cell's dimensions (typically 10mm × 10mm for engraving, 5mm × 5mm cuts)
- Count — number of steps in each dimension (5×5 or 7×7 is common)
LightBurn auto-populates the grid with incremental values and labels each cell with its settings. Click OK and the grid appears on the canvas.
Manual Array Method
Alternatively, draw a single test shape (rectangle, circle, or your actual artwork at small scale), assign it your layer settings, then use Edit → Array to tile it into a grid. Manually label each row/column with text objects showing the settings.
Running the Test
Place a scrap piece of your target material on the laser bed.
Frame the job first (press Frame in LightBurn) to confirm the array fits on your scrap.
Run the job. The grid will sweep through all power/speed combinations, producing visible results in each cell.
Reading the Results
After the burn:
For cutting: look for complete cut-through. Find the fastest speed at minimum required power that cuts through cleanly. That is your baseline. If a cell barely cuts through, add 5-10% power margin for real production.
For engraving: look for:
- Correct darkness — matches your target appearance
- Clean edges — no halo, no excessive burning into surrounding wood
- Detail retention — if testing a pattern, is fine detail preserved?
The sweet spot is where darkness/depth is right AND edges are clean. Too dark with ragged edges = too much energy. Too light with poor depth = not enough.
Saving to Material Library
Right-click the layer with your winning settings → Save Layer to Library.
Name it specifically: "Basswood 3mm Cut — Ray5 20W — 500mm/min 95% 2pass". Include your machine name. Settings from a 20W diode do not apply to a 40W CO2.
Over time your library becomes a reference you can load instantly instead of testing every session. Export the library file (Edit → Material Library → Save Library) and back it up — it is the most valuable file in your laser folder.
Tips for Better Test Grids
- Test on the same batch of material you plan to use for the job — different sheets vary
- Run cut tests with air assist on, since you will use it in production
- For photo engraving tests, use an actual small crop from your source image — abstract patterns do not tell you how skin tones or wood grain will look
- Run the test at the same ambient temperature as your work session — cold rooms affect power output on some laser controllers
- Take a photo of the test grid next to a ruler before you move it — this becomes your physical reference card