How the F did this happen

Last year I made this tray for my brothers kids to leave cookies and milk for Santa. Knowing his wife was pregnant I left room for another name. I went to add the new name and it’s so far off from where it’s supposed to engrave. Completely ruined the whole project. Can’t describe how mad I am

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When engraving on something other than Proofgrade material, you have to do two things to get proper alignment of your artwork against the object: make sure it’s within the focal range of the machine (the surface to be engraved has to be at least as high as the surface of the crumb tray would be), and make sure you set the material thickness correctly BEFORE lining up your artwork with the photo.

There’s a camera on the lid of the machine pointing at the crumb tray. It takes a picture of your material, which shows up on the GF application, bordered by some rulers, and you line up artwork with your material that way.

But how does the Glowforge know how big or small to make the camera picture so the rulers are accurate and you’re lining up your artwork with a life-sized image? After all, a 4 inch square of wood will look larger than 4 inches if it’s closer to the camera, and smaller than 4 inches if it’s further away from the camera. That’s just how vision works, right? It can only scale it to show up as 4 inches on your screen if it knows EXACTLY how far away that wood is from the camera.

Since the distance from the camera to the crumb tray is a known number, the only unknown is how thick your material is. If you use Proofgrade materials, the thickness is programmed in. It’s still an approximation, since every piece of wood or plastic varies a little from the next, but it should be pretty close. That means the camera picture will be scaled pretty close to “true to real size”.

But if you put anything else in the machine, it won’t know, and the picture won’t be the right size. If you line up your artwork with that picture, it will print somewhere other than where it shows on your screen. That’s what appears to have happened with your project.

To have an accurate picture, the machine needs to know the distance from the camera to the material surface. And you can provide that by measuring it, or asking the Glowforge to measure it. The “Set Focus” button tells the Glowforge to go measure the material height using its laser range finder on the bottom of the print head.

If you don’t use the “Set Focus” button before hitting the “Print” button, the first thing it does is go and measure the material height on its own, picking a point near the middle of your design as the place to measure it from. That’s what it means when it says “autofocusing on your material”, the first part of the “preparing” stage before the time for your print pops up.

If the measurement it comes up with is different from the height of the material you had selected, you’ll see everything “shift” on your screen as the camera image is scaled to true size. But if you had already used the “set focus” button before lining up your design with the picture, the image is already scaled, this step of “preparing your print” is skipped, and there will be no shift.

TL;DR: Use the “set focus” button first, and then line up your art with the now correctly scaled camera image.


thank you for taking the timer to reply. I always hit set focus first. I guess I should have double checked everything before hitting print.

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In cases like this, you could also do a very low-power pass to mark just the tape to confirm it will engrave where you want. Then, you can turn the power back up for the actual engrave.


Oh man that is irritating.

If the print head gets bumped, it will also lose track of where it is.

For a can’t-mess-it-up project like this, a test run on tape is my go-to move. I’ll usually put a bounding box around the art, and test that at minimum power. If it’s good, turn off the box and turn up the juice on the art.


This sucks. I’m sorry. I never rely on the camera for anything important.

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Great tip! Such a no-brainer that I hadn’t even thought of. Seriously, Thanks!

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Such a bummer! Great response above so nothing to add but empathy for what happened. I have a digital caliper that I use when engraving anything that’s not proof grade. And I do that a lot. I can never trust the “set focus“. It almost never gets it right. We were early supporters in the Kickstarter phase, and I have always been disappointed with the accuracy, or rather the lack of accuracy of the unit. It’s something we all learn to work around. I hope you have the original file and can re-create the whole piece easily. Sending you much supportive energy. <3

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