Yes although you could make a pair of depth gauges to judge the gap to the head is in range, which is the way cheaper lasers are focused.
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Shars sells some nice middle of the road calipers that seem to be accurate, display metric and Imperial units, and some models have a large display for aging eyes. The main issue I have with them is that you have to press the on/off button to power them up and some brands will power up when you move the jaws.
Same number of steps whether you enter thickness at the beginning or you enter position for the head to take the thickness. There is no way for the S/W to figure out where you want the design cut until you overlay the design. Easier for me to remember the material thickness for stuff that I have already used than it is to measure an X,Y every time. And you can’t place the design over the image until you have a good undistorted image, which means you would have to wait for the head to measure the thickness before placing the design, and if it measure in the wrong place on non-flat material or material that already has been cut then the material thickness is off.
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Great idea for a sanity check. Not a gauge from the lens, but more easily from the case bottom. I’ll get that out ASAP. Thanks for the suggestion.
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I’ve started a topic aboat calipers, in case anyone wants to put in their two cents…
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Great post.
I have a good supply of 3/4" goods, and measurements led me to 1/2" blocks on the bottom with an 1/8" shim on top supporting the 3/4 material, and telling the forge it’s looking at an 1/8" puts me in the ballpark.
With Dan’s assurance the tray dimensions are final I decided to bang out a platform of that I can drop in when I am addressing 3/4" material.
Kind of a go-nogo gauge from the bottom with increments like @dwardio’s that will land me in the focal range will be a handy project.
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Another post that has saved me a ton of time today. Thanks! Put it all in Excel so I’m good to go in the future. I’m an accountant so Excel is what I know… 
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Great write-up and it will come in handy in the future. I have a question though… a few days after I got the unit I was asked by a friend to engrave a large piece of wood, I posted about it in the forum (titled “Will it fit?”). The thickness of the piece of wood never came up in that post.
Long story short, I put a 1 7/8" piece of wood in the glowforge, entered the thickness in the uncertified material spot and it seemed to engrave it just fine. didn’t pop up any errors because of the thickness or anything. any thoughts on that?
I’ll assume you took out the tray, and that you gave the height in Total Material height - Tray Height?
Given those two assumptions, you did it perfectly right.
I put in the total material height and did not adjust for the crumb tray being removed. I thought the machine and software would “sense” that the crumbtray was removed and figure out the difference magically
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It kind of does. As I understand it, the “material thickness” you enter in the “use uncertified material” dialog is used to adjust the camera distortion to allow you to place your design accurately. If you put the wrong number in there, it will increase misalignment between what you see on the screen and where it prints, especially further from the center.
But the second thing is focus, which is entered in the “focus height (in inches)” box for each cut/score/engrave step. That height defaults to the same thing you put in the Material Thickness field, with one strange caveat: if you never touch the number, it will actually ignore what it says in the box and use the red laser to scan the height and auto focus. But if you change the number, it will ignore the laser auto-focus and use the focus height you set.
The practical upshot is that as long as you got your design close enough to where you wanted it and didn’t worry about camera alignment too much, the focus may have been done automatically even if the “wrong” number was entered.
That’s the way it has been explained many times, although I find it a super confusing way of designing a UI.
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Yes. It’s in the hopper to make changes to improve this, but right now, you’ve pretty much got it nailed.
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speaking of cutting without the crumb tray. Say I want to cut all the way through some 1 inch thick foam… what would you guys recommend putting underneath the foam? assuming I can cut through 1in thick foam.
a half inch (+) of wood - like a couple or three sheets of 1/4" Baltic Birch. That gets you in focal distance without bumping the head and if it cuts through (it should), you’ll be hitting the sacrificial wood and not the metal base plate.
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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.
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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.