I am having a very hard time finding the right settings (20 w diode Ortur laser, Lightburn) ) for engraving onto tempered glass. I am using grayscale, 500 DPI, and have set the power at various intensities from 50-100%, and speed from 60-90 mm/I. I have used xtool black laser paper to mask the glass, but none of my outputs seem to be that good. I have also tried placing a paper towel over the glass and spraying it with water. Any suggestions on settings or techniques? Thanks, Mark
First I’d like to point out, it’s the wrong laser for the job or the wrong tool for the job. If a laser beam isn’t blocked by the material of the object, the energy will pass through it with no damage.
You are using, what’s generally called indirect method of lasing materials the laser can’t do by itself.
This is generally accomplished by coating or adhering some type of material the laser will effect to the object. When heated, that causes the damage to the target…
The drawback of this method, is you lose resolution or cannot produce a dot the size of the laser beam. When you heat something else the heat transferred is larger than the laser spot itself, resulting in less resolution or lines/inch. Of course the advantage is you have a tool that can work, maybe not as well, but at no expense.
You’re asking for 500dpi, so your spot size has to be around 0.05, which is pretty small. Many diode lasers have a small spot, but most are rectangular and just under the 0.10 size… A 0.10 is 254 lpi/dpi…
Do you know the size of your lasers kerf in both directions?
You will have to choose a proper transfer medium, usually the darker colors work best as they absorb in the visible spectrum the best. Some people claim to use black marker pens with success.
Next you need to know how to adjust the machine or settings to the proper dpi/lpi that is best for your application/material and laser performance.
Laser Everything makes an excellent video on photo engraving. The video shows how to adjust dpi/lpi for any laser with any material. Something you will probably use your entire life with lasers… so I urge you to take the time and watch it… he does this on his fiber, but the procedure/technique works for any laser/material combination.
Settings are another matter. If you had the same kind of wood I did, the number would be in the ball park but still not right.
When you are stuck, there is a materials test Laser Tools → Materials test that will produce output to help you dial it in…
You still needs some kind of ballpark to start with and I can’t help you there… I’ve never used my led laser for this, my co2 is the right tool.
Others here have done it, hang around and someone will drop in with something for you, I’m sure…
Post some photos of your finished items… 
Good luck…
Thanks Jack,
This is a lot of info to absorb! I will try to do so.
No, I don’t know the kerf.
When you say It’s the wrong laser or tool do you mean it should be a CO2 or a bigger wattage diode?
The transfer medium is the xtool black laser paper. Having never used it before it’s been a pain to soak, peel off the backing, and apply to the glass without tearing it. Is there something else I could try?
If it wasn’t for the tempered glass I doubt I would be having this kind of problem.
Thanks,
Mark
A visible light laser is not going to work on something you can see through. The materials must block/absorb the energy of the laser beam… if it just passes through, it can’t damage the material. That is why you are using the dark paper…
I’ve seen many people use tempera paint, black markers, various lubricants and many other things to change how the laser effects the material.
There is also the Norton White Tile method that molecularly bonds TiO2 to glass and other materials… Some of us use it with water and lase it. The NTM usually uses paint, that you have to get off after you lase it…
@Bulldog does incredibly masterful work with this technique… lately he’s applied it to his new fiber laser…
Good luck
Thanks for your help!
Mark
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