I haven't been solely focused on the instructable
I did manage to test fly a new yet unreleased flight controller in my hex (worked great - can't wait to tell people about this thing when it hits the market hopefully later this month!) and did some more mirror tests of my own.
I found that greyscale doesn't really work well on mirrors. The problem is mirrors are binary. They reflect or they don't. Etching a greyscale into them does remove less of the mirror surface...but that doesn't really make it less "mirrorry". I noticed that areas that have a lot of detail on the back of the mirror still look all mirror on the front. I think a better approach would be to halftone the image and then burn that. Though I haven't tried it myself yet.
I've been focusing on trying to find the fastest highest quality way to do B&W artwork. Using the inkbot plugin in for crosshatching (found the actual hatch plugin - works way better than inkscapes built in hashing!) I found that I was able to do a very nice version of our MGM logo in wood in 7 minutes. The nice tight crosshatch comes across as almost perfect black. It does almost as well on a mirror...but the mirror doesn't come out quite as defined due to there not being any smoke/burning beyond right where the laser hits. So an even tighter hatch is probably needed for best results on the mirror.
I also compared two faster passes to one slower pass. The two faster passes was very slightly quicker overall and was very slightly more "clear" with more of the mirror backing removed. But it was also less precise and the fine details were not as fine. I found that for my mirror tiles full power at a feedrate of 600 seems to give very good results in a very reasonable amount of time.
Please disregard my messy "library" and laundry room reflected in the actual mirror
The quality is kind of easier to discern from the back with no reflections to get in the way:
Clockwise from the top left:
First try from image2Gcode
demo copy of laser etch from jtech (still the highest quality but slower than the vector methods)
Good results from this weekends test with inkscape hatching.
Decent results from pic engrave pro 5 but not quite as nice as laser etch
2 fast passes
1 slower pass
Lower power test to see how little power is needed to remove the mirror backing.
I've got to the point where I think I have a recipe I like enough that I'd be willing to do a full mirror tile with a logo and it shouldn't take a full day to engrave. But the smell of that pain ablating is just so nasty I still want to rig up a better fume extractor before I attempt it.
I also had some more fun testing on wood. Just really loving the laser. Being so much quieter than anything other than the drag knife and pen it's a lot more fun to test with than the spindle or needle cutter
And it can do so many neat things!
Really wanted to work on my vac table again this weekend...but enjoying the silence of the laser and had to get that instructable finished. Plus had to do some actual work this weekend working on some new virtual machines for our designers to help improve their workflow. But I didn't let that get in the way of having some laser fun.
Now...where did I put that fish pump...just had it out a month or two ago....