I was playing around with settings to etch on some glass ornaments tonight.
I coated the glass with liquid dish soap and had absolutely no idea where to start with settings. My first pass only etched about the top 1/5th of the image. I swear I had the Glowforge power set to 100 speed @500 and 270lpi but after my second pass I think perhaps my power setting was missing a 0 or 2 after the 1. These do have a curved surface obviously and I had my material thickness set for the highest spot on the ornament also.
For my second attempt I changed my material thickness so it was about half way between the thinnest area that would be etched and the thickest. I set power to 100 speed to 400 and 270 lpi. This cracked the bulb immediately.
Edit: If you look at this pic you can see the light etch from the first attempt, the laser is just approaching that point. also the soap had dried because this is the second pass on the same side.
Went through a few more rounds dialing the settings back as on each turn. After a total of five attempts and sacrificing 2 bulbs I settled on these settings:
Here’s the final product
I’m sure this can be improved on but at least if you want to do your own you have a starting point.