Why the sudden shift?

I don’t understand why this happens randomly. I will print something and it turns out perfect. Then, on the very next print, it doesn’t. This has happened now a few times; it’s frustrating to say the least.
I’ve made sure everything is clean so I’m dumbfounded. Any insight would be much appreciated!
Glowforge issue

Do you use ‘set focus’ before you place the design on the material? It needs to be used every time the lid is opened.

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Yes, every time without fail :frowning:

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Well, a way to see where it will print is to mask the material and set the power just high enough to mark the mask, maybe 3%, and see where it lands before the engrave. A pain, but it works.
How thick is your material?

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instead of doing the whole design, you can put a square around the design in a different color so you can disable it for the actual engraving.

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This one was about 1.5 inches. I’ve also had it happen with slate coasters.

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So your sure the air-assist fan shroud isn’t touching the surface? If the head touches something the calibration is lost. I know you have had your laser a while, I’m just brain-storming.

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My guess is you are moving the print head while changing material.

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The only way that happens is if the printhead is not where the laser thinks it is. It can be moved, hit something, or slip from the belt not being tight enough. How and when that happens can be discerned from the particular situation. Natural slate can be particularly tricky as it is not the same height everywhere and the camera focus is a very narrow range.

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Next time it happens you can download your logs and post them. The issues is likely in assuming GF is correct as opposed to trust your instinct. I black out my camera because it was better to stick with the math. It is always on point now.

You block out your camera , how does that work, with black tape over the Top Camera ?

That is not necessary. You can use the measure widget at the bottom left when the design is highlighted and that number is real even if the design does not look like it.

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The machine uses the lid camera when homing to line up with the print head with its grid. After that point the only function of the camera is to provide the user a view of the bed. However, your machine has a grid that it actually operates on. I tape off the lid camera if I am about to do a ton of marble engraving because the dust just mucks up the camera anyways. I use coordinates and a grid for lining up instead of the camera.

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I’m certainly intrigued! Would you mind explaining your process in a little more detail?

Yup! Here is a tutorial on it and the grid file: Grid update and more free cutout files

The easiest way I have found to explain it is the calibration print for a new print head, which is a 20 minute print that “aligns the printer head with the rest of your printer”. So if it takes 20 minutes for the machine to align with the print head, then you know it is not doing it each time before you print. Meaning that your machine already has your print head mapped out to the machine and is using the information from the print head setup any time you print. So with the grid method, you are basically asking your machine to show you where it understands the coordinates to be.

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Thank you for SVG file but I am still confused with the Manual Focus as to the Set Focus if the camera is only used once in the Process.

Do you ever use the Manual Focus or the Set Focus or do you let the machine fall where it may and then Jig to those areas ?

Thank you

If I am using auto for material height then I set focus on the surface of the material (I put my design in the coordinates I want and then click to set focus where the design is) so that it can determine my material height. If I am using manual for material height then I type in the material height and set focus anywhere.

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