Based on this write up, is the largest items you could engrave with the Glowforge 1.8" ?
I have something I’d like to engrave but when I measure it with my calipers it seems like it is 1.85", which tells me I shouldn’t do it. I was hoping that without the tray in I could just sit the item on the bottom of the GF and just engrave away!
I figured I’d ask in case I’m missing something… Thank you!!
@henryhbk I have a GF Basic and I read in the specs we can use something that is 2” in height, but I’m not sure that is aligned to your tutorial (unless I’m misunderstanding)
I have a box/sign I purchased from AC Moore that is around 1.85” tall.
If I do the calc of:
1.85 - 1.4 (tray removed) = .45 material height.
It seems like, based on what I am reading, it will be too tall to engrave…yet the object is still less than 2” tall…
Am I misunderstanding something?
Thank you!!
Remove the crumbtray. Put the sign on the floor of the GF. Enter 0.45" for material height. The max material height entry has been increased to 0.5" since this topic was started back in May 2017.
So it should work then? Is a 2” thick piece of material going to fit like the specs say?
Thanks again!
I think so, but it’s real close. The air assist port hangs down behind the head. Not near my unit to measure.
Thank you! This really gave me some confidence. I used a more rudimentary method. Use a rigid scrap to measure the top of the crumb tray when partly inserted with a mark on the scrap. Remove the crumb tray and place your piece with a riser piece underneath to lift it around 1/4" above the crumb tray height. I wasn’t cutting, just etching. Mark the height of the surface of the piece to be etched on the same scrap. Measure the difference from the first line to the second line (convert to decimal on Google) and that is the number to be entered in your material thickness! Worked great.
This was incredibly helpful. I was testing cutting on a wood cutting board without the honeycomb tray with no success. Then I stumbled on these instructions and fixed my problem. The results are beautiful! THANK YOU!
glowforge calculator.pdf (16.9 KB)
Not sure if anyone wants this, I took the steps above and created a PDF calculator that will help with your final number.
That might be easier for some folks to use, thanks for sharing it! 
I get 1.35" for the tray height. If you pull the tray out and measure the plastic sides (which it sits on… not the legs that go down in the notch), and then subtract the little lip height between the side and the honeycomb, I got 1.35".
Somewhat minor difference, I’m not sure how much it matters.
VERY minor, indeed. 
I’m new and just got my Glowforge. Let me get this right…even without the crumb tray, the top of the material needs to be in the 1/2" zone between where the honeycomb tray sets and the laser head? Therefore, I cannot enter a material thickness with a negative number to set the height of the material if the crumb tray isn’t in place? Instead, I would need to build up the material with another object to get it to this zone? I just want to make sure that I understand. Thanks in advance… Matt
Correct on all counts.
Just to explain why - the beam focuses at a specific distance from the lens. To achieve focus for materials of varying heights, the mechanism in the head moves the lens up and down. The crumbtray surface is basically the zero mark - below that spot, the beam can no longer be in focus.
Thanks so much for this! Used it twice and got a perfect cut right out the gate! I’m terrible at math and Excel, so I never would have been able to work this out on my own. Much appreciated!
It looks like it’s been a little while since this tutorial was written and some improvements were slotted for the GUI. If the material is raised so that the surface is in the 1/2" zone above the honeycomb, is it still necessary to do these precise measurements and enter in the adjusted material thickness into the UI to get accurate alignment between the camera and the material surface?
For now, yes. 
thanks for the update!
Well even if the GF would do it itself, for safety you need to make sure you are clear of the nozzle so you don’t hang up on the head.
