Etching underside of Glass Plate

[William Milligan]

I have a customer who would like me to engrave/etch the underside of a few glass dinner plates. They want a celtic knot design around the outer edge and some additional knot work in the center (bottom) of the plate. My concern is that the dinner plate obviously is angular...though the design work won't cover more than about 1/4 to 1/2 an inch I am thinking some of it might be out of focus and not get properly etched. I was thinking I'd have to manually focus at the center point of where the design would be and then try to run the job. I am wondering if anyone has done anything like this and how much focus variance/allowance there is with a 2" lens. Any advice is appreciated...thanks!

[Gary Hair]

Sandblast, sandblast, sandblast.

Glass and lasers don't belong together, especially when you have a surface that isn't flat or level.

A laser is a great tool but you need the right tool for the job and sandblasting is it.

Gary

Just because the only tool you have is a hammer doesn't mean everything is a nail...

[Gary and Jessica Houghton]

My husband laid out a design for the rim of a glass plate. We focused on the middle portion of where we were to engrave. Engraved small dots. Then lined up the glass where these dots were (while on a more level surface) and engraved. It was cumbersome and I vowed never to do that again! I agree with Gary, sandblast!

[Tim Bateson]

No issues at all. Just as the previous post, focus on the middle - measure the peak and the low point & focus in the middle. Unless the difference is over 1/8 inch it's not an issue. I've done a couple with much more difference than that and I can just barely see any softing at the edges & I'm VERY picky about my finished works.

Yes, sandblasting is the ultimate tool for glass, but for a couple plates the laser is much faster. (in my humble opinion)

[Riki Potter]

Hi William,
I've lasered alot of odd-shaped things with angles on them. My method was to use sticky paper on the surface and print with speed: 100 power:10 to mark the paper. This will give you a good idea of how it will turn out, also really helpful for placement/size/etc.
If I'm doing lines of text of seperate objects I'll sometimes set it up so I refocus for each line of text to get it larger, if it's one object you really want to do it in one go so see if you can figure out exactly how far you can push the size before the edges fade to much for your liking. And like the others have said focus at the centre of the slope your engraving onto.

Good Luck!