Birch plywood is the king of laser cutting: dense, regular and free of through-knots, it gives clean edges and high-contrast engraving. It is also the best starting point when learning to dial in a machine.
Settings: what really matters
When cutting, power is almost always set to maximum and speed does the work: too fast and the pass will not go through, too slow and the edge chars for millimetres. On a 10 W diode expect two or three passes for 3 mm; a 40 W CO2 goes through in one.
When engraving it is the opposite: keep the speed high and modulate power between 15 and 40 % depending on the contrast you want. 254 to 300 DPI is plenty — beyond that the wood starts burning between lines and the artwork closes up.
Air assist makes a real difference here: it blows smoke away from the focal point and roughly halves edge charring. If your machine has it, keep it on while cutting.
Risks and precautions
Plywood is glued: urea-formaldehyde glue gives off irritant fumes, and cheaper panels contain glue pockets that abruptly stall the cut and cause flare-ups. Extraction is essential, and a long cut is never started unattended.
Beware of panels sold as "plywood" but faced with melamine or varnish: the film may be chlorinated. If you do not know what the coating is made of, sand it off or change panel.
Finishing
Paper masking tape applied before cutting prevents smoke halos on the visible face; peel it off afterwards. On an already stained piece, a melamine sponge or a very light 240-grit sanding is enough.
Birch plywood takes hard wax oil very well: engraving turns deep brown instead of dull grey. Avoid spray varnish on fine engraving — it fills the recesses and flattens the relief.
Every figure on LaserSettings comes with the machine, the laser source, the material and the thickness it was tested on. A setting published for a 10 W diode says nothing about a 40 W CO2, and a setting for 3 mm says nothing about 6 mm: check those four things before you copy any number.
Settings are confirmed or disputed by the members who reproduce them, so reliability comes from cross-checking rather than popularity. Photos of the result — cut edges, engraving shades, scorching — tell you more than a single number found on a forum.
Whatever the material, treat a published setting as a starting point: run a small power/speed test grid on an offcut, clean the lens, redo the focus, work with fume extraction and air assist, wear glasses rated for your wavelength and never leave the machine unattended.