Laser cutting and engraving wood: species, starting values, fewer burn marks
are explained briefly when you hover over or tap them.
Wood is the material almost everyone starts with. It absorbs the light of diode and CO₂ lasers well, engraves with nice contrast and is inexpensive. Even so, every species behaves differently, and with plywood it is often the glue that decides whether a cut goes through cleanly.
Wood species at a glance
| Wood | Engraving | Cutting | What to watch out for |
|---|---|---|---|
| Poplar plywood | light, medium contrast | easy | cheap and soft, glue quality varies widely |
| Birch plywood | fine, good contrast | needs more power than poplar | harder and more dimensionally stable, more glue layers |
| Basswood plywood | very even | very good | manufacturer cutting figures often refer to basswood |
| MDF | evenly dark, no grain | good, but a lot of smoke | fibres bound with synthetic resin, strong extraction needed |
| Solid wood (maple, alder, cherry, walnut) | very attractive depending on species | only thin thicknesses with diode | resinous softwoods burn unevenly |
| Bamboo | dark, high contrast | possible | usually glued strips, glue joints can become visible |
Light, even woods such as basswood, maple or alder show engravings most clearly. Dark woods such as walnut give less contrast but look more refined.
Engraving and cutting
When engraving, the laser travels line by line over the surface and burns the top layer. The wood becomes darker, and with more energy also deeper. When cutting, the laser follows a line at full or nearly full power and low speed until the material is cut through. The differences are explained in the article Engraving, cutting, marking.
How thick a diode laser cuts depends heavily on its power. A few manufacturer figures from the device overview as a guide:
- xTool S1 20W: up to 10 mm basswood plywood in a single pass
- xTool S1 40W: up to 15 mm basswood plywood in a single pass
- xTool P2S (55 W CO₂): plywood up to 12 mm recommended, solid wood up to 18 mm
These are best values under ideal conditions. In everyday use with ordinary craft plywood you are better off expecting considerably less.
Glue in plywood
Plywood consists of thin veneer layers that are glued together. The glue absorbs laser light differently from wood. Where glue collects, the beam gets stuck, and spots appear where the cut does not go through. Cheap construction plywood also often has gaps, knots and filler in the inner layers.
That is why there is plywood sold as “suitable for lasers”. It has even layers and few gaps. For projects where parts have to fit into one another, it is worth it. If a cut only fails in individual places, it is usually down to the material and not the laser. More on this in the article Laser does not cut through.
Grain
Wood has light earlywood and darker latewood zones. The denser annual rings burn more slowly than the soft wood between them. On solid wood with strong grain, a solid-area engraving therefore becomes streaky. With photo engravings this is particularly noticeable.
For photos and fine areas, woods with calm grain are suitable: basswood, maple, alder or good plywood with an even top veneer. Pine and spruce, with their hard annual rings and resin pockets, give uneven results. MDF has no grain at all and engraves very evenly, but more brownish than black.
Starting values per power class
The following ranges are rough starting values for 3 mm poplar or basswood plywood. They do not come from a single manufacturer table but are a guide for your first test grid. If your manufacturer offers material profiles for your machine, these take priority. Power is given as a percentage of maximum power.
| Task | 10 W diode | 20 W diode | 40 W diode | 40 to 55 W CO₂ |
|---|---|---|---|---|
| Engraving, light | 30 to 50 %, 100 to 200 mm/s | 25 to 40 %, 200 to 400 mm/s | 25 to 40 %, 300 to 500 mm/s | 15 to 30 %, 300 to 500 mm/s |
| Engraving, dark | 60 to 80 %, 80 to 150 mm/s | 50 to 70 %, 150 to 250 mm/s | 50 to 70 %, 200 to 300 mm/s | 30 to 50 %, 200 to 400 mm/s |
| Cut 3 mm | 100 %, 3 to 6 mm/s, 1 to 2 passes | 100 %, 6 to 12 mm/s, 1 pass | 90 to 100 %, 15 to 25 mm/s, 1 pass | 60 to 80 %, 15 to 25 mm/s, 1 pass |
For comparison, two published profiles from xTool’s material database: engraving 4.5 mm birch plywood with a 40 W diode at 300 mm/s and 50 %, and engraving 3 mm MDF with a 10 W diode at 200 mm/s and 40 % in two passes.
As line spacing for engravings, 0.1 mm is a good start. How power, speed, passes and line spacing interact is covered in the article on laser parameters. How to build a test grid is explained in the article Material test. Do this with every new wood board, even if it looks the same as the last one.
Reducing burn marks
Smoke and resin settle as yellow-brown edges beside the engraving and cut. You cannot avoid this completely, but you can reduce it considerably.
- Use air assist: An airflow right at the nozzle blows smoke and flames away. When cutting, air assist is almost mandatory, while for engraving less air is often enough.
- Cover the surface: Masking tape or transfer film on the surface catches the smoke. You peel it off after lasering. The engraving becomes minimally lighter as a result.
- Check the focus: An unsharp spot spreads the energy, and the wood chars more widely.
- Several fast passes: Two passes at higher speed often burn the edges less than one very slow pass.
- Protect the back: On a honeycomb bed, reflection marks appear on the underside. A slat bed or spacers help.
- Finishing: Light discolouration comes off with a damp cloth, a magic eraser or fine sandpaper.
There is more detail in the article Burn marks.
Safety
Wood burns. When cutting at low speed, flames appear, especially with resinous wood and when air assist is missing. Never leave the laser running unattended and keep a suitable fire extinguisher within reach. MDF and plywood release a lot of smoke because of the binders. Vent the exhaust outside or use a filter designed for laser smoke. Wood with varnish, stain or a coating whose composition you do not know does not belong in the laser. What else is off limits is covered in Materials to avoid.
Continue with: Material test and Burn marks.
How to get photos onto wood, with image preparation and dithering, is covered in Laser photo engraving.