HDPE — jerrycans, plastic cutting boards, thick bags — cannot be laser cut. It does not vaporise: it melts, sticks, drips and catches fire. There is no acceptable setting, whatever the machine.
What actually happens
HDPE has a very low melting point and low thermal conductivity: heat stays concentrated, the material pulls back from the line and forms a bead, then drips onto the bed. The part is lost before the first pass even ends.
Molten polyethylene ignites easily and keeps burning while dripping, which spreads flame under the part, where extraction does not reach. It is one of the most common fire scenarios in a laser workshop.
What to use instead
For a rigid, machinable technical part: Delrin (POM) with a CO2, or cast acrylic if flexibility is not needed.
For a kitchen board: solid bamboo or beech, which engrave and cut cleanly. For a flexible container: mechanical cutting, never a laser.
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.