Calibration Sadness

I’m puzzled by the calibration results I’m getting, and even more puzzled by the ‘confirmation test’ that is supposed to show it’s working.

I cleaned all the glass and ran a calibration this morning. Then, I followed the instructions to print the ‘precision calibration target’, and observe that the laser managed to score underneath the artwork on the screen. It did.

That doesn’t actually matter, though. The post-process image in the Glowforge UI is not the product. What matters is being able to place a process step accurately on the workpiece, and there things fall apart. I took the test sheet of cardboard, rotated it 180deg and then attempted to put a second copy of the target over the first one. Here’s the result.

I know this is the worst case (opposite corners of the crumb tray), but this is pretty bad. What am I missing here?

Just making sure - after you rotated the cardboard you used set-focus on the new spot, and then aimed using the GFUI, correct?

I ask because without the set focus then the GFUI is showing you it perfectly aimed for the top left - and not the lower right at all. Each set focus only works for the one spot you aimed it at.

Ah, good catch. I did set focus before each print.

1 Like

I’m even more confused now. I just repeated the test to be sure I’d set focus, and absolutely nailed the alignment on the second print. Like, looks like a 2-pass score without moving the workpiece. Great success, I must have missed that step the first time, except…

…the camera image, before or after doing another set focus, was way off. Doesn’t matter, but is strange.


The camera image will reset based on what material you have selected as a default. The set focus uses that exact spot - so yea, the post image is not to be trusted! (That includes after you’ve hit print, sometimes the image changes - don’t stop and realign, the actual cutting spot hasn’t changed, just the camera angle)

FYI - this is what the bed looks like before they use their maths to make it seem flat:

Yup, that pretty clearly shows why the image quality is so poor at the corners. Not many pixels out there. :slight_smile:


Thank you very much for the help, @deirdrebeth! @zandr, I extracted the logs from your Glowforge to investigate your calibration results, and I noticed that the material you used for your precision preview shifted somewhat during the calibration process. This may be the cause of the difference you described with that most recent picture.

Do you have a sturdy piece of material, such as a sheet of draftboard, to use for the camera recalibrator? If so, could you please run it one more time using that material, and let me know the results?

1 Like

@vee Not at the moment, but I can certainly anchor another sheet of that cardboard and try again. Will advise.

It’s been a little while since I’ve seen any replies on this thread so I’m going to close it. If you still need help with this please either start a new thread or email