Weard laser result on stone


With my glowforge i sometimes laser house numbers into stone (mail boxes etc etc)
already done this about 30 times with no problem and it works perfect.

I was doing 1 stone again today and the results was something completely different.
1: The number 7, was not as smooth as normal en very unstable.
2: The glowforge made a clone 7 above the original one, and made it even bigger.

So i have no idea what is going on… Maybe somebody can help me, how to fix this issue?
Thank you, (sorry for my crappy english)

Your English is not crappy, and is quite good for not being your first language!

Was this a different type of stone than you’ve worked with before? Did it have a lot of mica or quartz in it?

Did you have the material height (thickness) set correctly? (guessing you have to remove the crumb tray to fit the stone in and stay more than 1/2" (12.5mm) away from the head).

If the stone is not where the head is trying to measure focal length before a job and it tries autofocusing on the edge or even the bottom of the unit, this would confuse the GF, especially since the bottom is reflective–and any surface that is reflective is not good for the laser, and might be related to what has happened here.

Has it happened again with another stone, or other material with the same set up? One idea if it is due to reflection off the bottom, is place a dark sheet of paper or cloth on the bottom.

Did you watch the laser while it was running and see what order of the two 7s were etched? This might be useful for the problem solving. From the photo, it looks like it etched the “clone” first, and then the 7 in the position with the artwork (since the more solid area of it is over top the lighter clone). Not sure if the order is significant, but might help in the trouble shooting/problem solving.

Hope someone else with more experience with these materials or operating without the crumb tray can help figure this out.

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Even not knowing the differences in the stones doing anything on a curved surface is a problem. The laser has a focal point that it does its best work and above or below that point is less effective. Add to that the fish eye lens that is doing all sorts of complex math about angles and so the distance it is thinking things are will be off with the amount of distance from where they actually are as well.

That you have been able to get a lot of pieces made already is pretty amazing, but you will want to have that cutting face as flat and horizontal a surface as possible. After that of course different stones will engrave differently depending on the materials it is made of even on different places on the same stone. If one stone does not work for any of those reasons I would just use a different stone.


I’m so sorry that print didn’t come out as you expected.

I would like to check over just a few more things. Could you do the following for me?

Please send photos of all your cleaned optical components, with special attention to any damage you might find:

Once we have those pictures, we’ll follow up with next steps.

Thank you all for the reply’s.
Couple things: 1: its not a stone / stone but more a slab of stone so there is no curve. (the slabs are always the same)
2: it started with the normal 7 first (i always check to see were he starts the proces)
(feature idea, i also have a plotter, and before i cut i can see a previeuw were the cutter starts how it moves and were it ends, that way you can check the print/laser before putting the material at risk)

Yesterday morning i tried to do the same print again (but with a bigger number to cover over the old ugly one) and polish the clone 7 so its not visible.
and it worked, everything was the same as all the stones before.

So i stil have no idea, why the glowforge was behaving so weard.
I did notice that the glowforge was responding way faster then the day before.
Could it be a update that was going on at the same time? or unstable wifi connection?

The cleaning protocol suggestion is not a bad idea, wil do that to keep the glowforge in shape :slight_smile:


I’m glad you resolved it! I’m going to close this thread. If you run into any other trouble, please start a new topic, or email us at support@glowforge.com. We’re here to help!