The Importance of Material Tests

 

One of the biggest misconceptions is that a single preset will work for an entire category of material. If you buy a sheet of 1/4" birch plywood from a local big box store , it will likely require completely different settings than 1/4" birch plywood bought online from a laser supply vendor.

Why? Because what's inside the material matters just as much as the species:

• The Glue Factor: Plywood utilizes various glues to hold its layers together. Exterior-grade glues are highly laser-resistant and require significantly more power to cut through than interior-grade glues.
• Density and Moisture: Natural materials have knots, moisture variances, and density changes.
• Acrylic Differences: Cast acrylic engraves to a beautiful, frosty white, while extruded acrylic cuts beautifully but engraves with a clear, messy edge.

Without a quick test, you are firing blindly into an unpredictable target.

You're Not Wasting Material

It feels counterintuitive to cut or engrave a test grid onto a perfectly good piece of material because it feels like wasting stock.

But consider the alternative: You guess the settings for a large, intricate 45-minute project. The laser finishes, you lift the lid, and you realize the laser cut through 90% of the piece but left a few sections completely uncut because of a dense core. The entire project is ruined.

By sacrificing a tiny 2" x 2" corner of your material to a test matrix, you guarantee that your actual project cuts flawlessly on the first try. You aren't wasting material; you are buying insurance.

 

You're Protecting Your Hardware Too

Laser tubes are consumable items—they have a finite lifespan measured in hours. Running your laser at 100% power all the time drastically shortens that lifespan.

When you run a test matrix, you often discover that you don't actually need 100% power to cut a material. You might find that 65% power at a slightly slower speed yields a cleaner cut with zero charring. By finding the minimum effective power required for a clean cut, you keep your tube running cooler, saving you hundreds of dollars in premature replacement costs.

The 5-Minute Habit That Changes Everything

Most modern laser software, like LightBurn, has built-in Material Test Generators (found under Tools > Material Test). It takes less than 60 seconds to set up, a few minutes to run, and gives you a permanent physical reference guide for that specific batch of material.

Before you hit "Start" on your next big project, take the time to test. Your wallet, your laser, and your customers will thank you.

 

HOW TO RUN A MATERIAL TEST IN LIGHTBURN

 

Step 1: Accessing the Generator

1. Open LightBurn.

2. In the top menu bar, click on Tools and select Material Test Menu.

Step 2: Configuring Your Grid Settings

A dialog box will appear allowing you to define the boundaries of your test.

• Parameters: Set one axis to Speed and the other to Power.

• Count: Choose how many rows and columns you want (a $10 \times 10$ or $5 \times 5$ grid is standard).

• Speed Range: Set your minimum and maximum limits based on your laser's capability (e.g., $10\text{ mm/s}$ to $100\text{ mm/s}$ for cutting, or $100\text{ mm/s}$ to $500\text{ mm/s}$ for engraving).

• Power Range: Set your minimum to 10% or 15% (below this, CO2 tubes rarely fire) and your maximum to around 80% to 90% to protect your tube lifespan.

Step 3: Editing the Material Settings

Click the Edit Material Settings button inside the generator. This tells LightBurn what type of operation you are testing.

• If you are testing for Engraving, set the mode to Fill.

• If you are testing for Cutting, set the mode to Line, and ensure you define a realistic thickness or pass count.

Once configured, click Preview to verify the pathing, place your scrap material in the bed, focus your lens, and click Start.

How to Interpret the Finished Grid

Once the laser finishes, you will have a physical matrix of squares showing different speed and power intersections.

If You are Testing for Engraving (Fill):

• Look for Depth and Contrast: Find the square that gives you the darkest mark with the cleanest edge.

• Watch out for "Charring": If a square looks deeply cratered, burnt, or leaves a heavy layer of soot, the power is too high or the speed is too slow.

• Identify the Efficiency Winner: Look for the highest speed that still gives you a dark, crisp mark. Running at $400\text{ mm/s}$ at 40% power is much better for production time than running at $200\text{ mm/s}$ at 20% power, even if the darkness looks identical.

If You are Testing for Cutting (Line):

• Flip the Board Over: The perfect cutting setting is the one that just barely pushes cleanly through to the back of the material with minimal charring or flashback marks.

• Check the Dropouts: Pick up the sheet. The squares that drop out smoothly on their own represent your reliable cutting zone.

• Add a Safety Buffer: Once you find the fastest speed that successfully cuts through, decrease that speed by 10% for your production files. This ensures that if the laser hits a hidden glue pocket or dense knot in the wood later on, it will still cut completely through.