Glasses

[michied]

So I had a Glowforge plus and did glasses and they didn’t crack, now I have a Pro they are cracking but not all the way threw, behind the word, I tried lower power, than it won’t engrave it all, is there a setting , plus my manual settings not all showing up.

[tjones]

I haven’t tried glass yet, but I have seen a lot of people rubbing a coating of Dawn dish soap on their glass before engraving to prevent cracking.

[David.W]

This question is outside our team’s scope. I’ve moved it to the Beyond the Manual so the discussion can continue there.

[cynd11]

If you do a forum search for “engraving glass” you will get a number of hits that give suggested settings for this.

Regarding manual settings disappearing—keep in mind that settings only appear for the operation you saved them for. So for instance your manual engrave settings won’t show up if you have Cut selected. And also, if you saved Engrave settings for a vector engrave, they will not show up for a bitmap Engrave, and vice versa (because the options are different for those two types of engraving).

[eflyguy]

Once you have your settings figured out, save them as a custom setting. Then you won’t have to worry about them again. Perhaps that’s what you mean by “manual settings” - then, as stated, bitmap/raster and vector engrave settings are separate, one won’t show for the other type of image. You need to save them separately.

I engrave shot glasses and glass spice jar lids without applying anything to the surface. You just need to fine tune your settings for your material. Not all glass is equal, so (again) you need to test and find settings that work for your material and your machine. That often means sacrificing a piece to figure it out. edit - not all material is suitable for laser engraving.

[SpecterWorks]

Hmmm… Have you engraved these exact glasses before? If not, it could be an issue with the glass itself. Sometimes higher end glass (usually referenced as crystal glass) will give people trouble. That has to do with how the glass is formed at the microscopic level. It is a single crystal, and so the internal stresses due to heating (and the associated thermal expansion) will cause the glass to shatter or crack.
Ironically, it seems that cheaper glass is better suited to lasering, specifically because it doesn’t tend to form as a single crystal. If this is high-end glass, and your heart is still set on etching, your best bet is probably to use the laser or some other high-precision machine to create a mask (cricut, etc.), and use either the sand-blast or chemical etch methods. Just make sure any masking material is “laser-safe.”