Glasses were done on a chuck type rotary. Rotary has been “pimped” out with a few minor mods, like leveling feet so I can tip the rotary up at an angle to get the glass surface parallel to laser travel and a cone at the “dead end” to hold the open end of glasses. Somewhere there’s a “rotary mods” thread that shows it. Ahh, here it is: Rotary chuck mods or accessories
80 watt Ruida red&black. Speed around 400mm/s. Power for these was 17%. DPI = 300. Power requirement can vary a LOT between different types of glassware. Too much power seems to lead to chipping around the edges of designs and letters. Go easy.
No coatings. I wash and dry the glass, put it in the chuck and blast it.
I usually use a 2” or even a 2-1/2” lens.
When I started, I used 1-1/2”because in theory the dot size is smaller and resolution better.
The problem is that glassware can be amazingly un-round. You can put a glass in the chuck, measure for perfect focus, then rotate the glass 45° and find you’re 2 mm or more out of focus because the glass is slightly oval or has a side with a bit of a flat spot. Add to that the fact that a lot of glassware (like wine glasses) can have a lot of vertical curvature and that adds greatly to the focus problem. You need a pretty good depth of focus to do glassware.
It took me quite a while to figure out decent settings for my machine. Dollar store glasses are good practice. I learned a lot from wrecking $20 in cheap glassware.