OK, so I don't let things go easily and sometimes it pays off. Not always, but it did again here. I added air assist to my K40 laser setup and now I can get consistent great looking solid etches on anodized aluminum. I'll use all this work to put some graphics on the aluminum panels of my Wonderswan battery packs. You can see the clean looking etches below. It took another laser upgrade, several days of tuning, and a lot of panel test etches, but it all paid off.
The last part to really clean up the solid etching was air assist, which keeps fumes off the final focus lens, and also helps to cool the aluminum. Focusing was also a major tuning process. I also put in a high quality focus lens and final mirror in the laser head. A 4am laser etching session let me work through the focus tweaks and then another two days to tune power and speed. As well as 20+ test aluminum panels, front and back. :-)
I'm pretty happy about how this all turned out and now I have a direct product need for my K40 laser. I'll laser etch my own graphics on my WS battery packs. I also used my K40 to prototype ideas for HyperBoy but I ultimately chose to let my vendor laser etch them.
One of the solid etch panels in an assembled WS battery pack is shown below.
Looking forward to future projects where I'll put my K40 to more good use.