Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4709298.
i designed this to help me focus the laser at the best position. you have to engrave each section one at a time.
for example, you will have to cut out of 1/8 plywood or similar), or use any gages that take you thru 25 to 35 mm.
then setting the laser head or module to the 35mm spot on the gage, you then engrave the 35mm engrave only. you will need to hide the rest of the others so they dont get engraved yet.
then setting the laser head or module to the 34mm spot on the gage, you then lower the laser to the 34mm level, with only the 34mm section showing, engrave that.
etc., etc... until you are done at the 25mm section.
then you look for the section that gives the best results and there you have it. the best focus for your laser
i did it in lightburn in inches so you might have to change to mm. the gage is done in mm but not the sections from 25-35 which are in inches.
set your speed and power settings and keep them the same all the engravings.