This page describes a laser engraving setting published for Acier peint / laqué at 2 mm, tested on a Longer Ray5 5W fitted with a Diode 5.5W source (445 nm blue diode, 5 W). It states the exact machine, source, material, thickness and operation of the test; power, speed and number of passes are shown with a Premium pass.
Why those four facts matter: a engraving setting that works on Acier peint / laqué at 2 mm does not transfer to another thickness, nor to another source. A 445 nm blue diode rated 5 W does not deposit the same energy as a stronger module, and the speed has to be adjusted accordingly. Copying a number without checking those four points is the first cause of a ruined part.
Published by LaserSettings (estimation). No other workshop has confirmed it yet: treat it as a starting point, and confirm it from your account if you reproduce it.
No photo comes with this setting yet. If you reproduce it, publish yours from your account: a picture of the result is worth more than a line of numbers.
Recommended routine before running the part: clean the lens, redo the focus, engrave a small test grid on an offcut of the same Acier peint / laqué, then adjust the speed rather than the power. Work with fume extraction and air assist, wear glasses rated for 445 nm blue diode, and never leave the machine unattended.
Longer makes entry-level diode engravers and higher-power module models, with a touchscreen and aluminium frame. They engrave light wood and leather cleanly; on acrylic, only opaque colours react, as with any blue diode.
On painted steel the laser works the paint, not the metal: it removes the coating to reveal bright steel underneath. This is the one case where a blue diode gives a crisp result on metal.
The goal is to remove paint without heating the steel: medium power, high speed, single pass. A second pass does not make the line clearer, it widens the area where paint blisters around the design.
Contrast depends on the paint: matt black lacquer gives a very visible mark, pale or metallic paint much less.
A fibre source goes through the paint and then marks the metal: deeper, but less contrasted than a clean diode strip-back.
You do not know what an industrial paint contains: some primers and powders give off frankly toxic fumes. Serious extraction, and avoid painted parts of unknown origin.
The bared steel is no longer protected: on an exposed part it will rust. Clear spray lacquer over the mark solves it.
A dry cloth is enough afterwards: avoid solvents that would attack the paint around the design.