Object moving before print

Not sure where to post this, but we are having issues when we get a graphic set on the material, we hit print and it moves. Then we have to cancel the print and move it around again. This seems to be happening very often and its getting costly. Any info would be appreciated.

Are you familiar with/using the set focus tool? Basically, you click set focus, then click on the material itself. This will make the machine move the head over the material and measure a distance to it (you can watch the actual glowforge and will see a red dot appear for just a second-make sure the red dot is actually hitting the top of your material). The camera view then adjusts for the height of the material. If you don’t use the set focus tool, the GF does this automatically when you hit print and this is why it appears that the graphic is ‘moving.’

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Warning: long explanation incoming.

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… unless you provide the material’s thickness.

And you can do 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!

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That makes sense. We are using nonPG 1/4" Maple yet we select thick maple plywood cause we find that works the best for cutting and engraving. Perhaps I should input the size instead. Thank you so much for the explanation.

It’s actually not as much about setting the size manually. The key is to click Set Focus and click on the sheet of material in the camera view-this will ‘correct’ the camera view for your material thickness so you can more accurately place your graphic visually on the material.

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No, don’t enter the thickness manually. Use set focus. Let the machine work for you. Just make sure the red laser shines on the piece and not beside it. Then place your artwork and it will be perfect.

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I’d just add that if you haven’t done the camera calibration, do that first. Set focus won’t necessarily resolve the issue if your camera isn’t properly calibrated.

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If the image on your screen moves, the above explanations may solve your problem, but if the material physically moves, then it may be thicker than 1/2 inch and is being nudged by the head fan when it passes over your material. Check your thickness.

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