Auto Focus Height Seems Incorrect

Hi! So, has anyone else experienced the auto-focus to be very wrong?

I’m working with some hardwood that’s roughly 3/16" thick. It calipers in around 0.2" and when setting the material height to 0.2" it aligns nicely.

Now, at first, it cut and engraved wonderfully and as expected at that focus height. But now, it cuts and scores incredibly BOLDly. When setting the focus height to 0.12" it seems more in line with what a cut should look like.

Also, when I click Print and it auto-focuses, the image changes and shows very misaligned compared to what it showed before. This leads me to believe that the auto-focus is way off base.

Any ideas?

Are you using the set focus command and seeing the misalignment or relying solely on the first focus image the GF takes when the lid is closed?

When lid is closed, it shows it correctly. Perhaps this is because it’s going off of the set material height.

When doing Set Focus, it’s incorrect, just like the autofocus step of Print.

Two things I’d look at. When using set focus watch the laser head and material to make sure that the red laser dot lands on your material surface and not in a hole or otherwise off. The other is to run the camera calibration if you haven’t already; it’s the best way to get an accurate image. It often needs to be run again if the machine has been moved since the last calibration.

The calibration of drawing 100 :glowforge:'s? I was wondering if that was supposed to help with the focus height. Maybe I’ll give it a go.

This seems to have just suddenly happened. Maybe after I had tried wiping the lens? I’m not sure though, as it’s possible I tried wiping the lens after some cuts weren’t working right, which could be because of this issue.

Are you certain you didn’t put the lens back in upside down?

The camera calibration process is strictly for aligning the lid and laser head cameras, so that designs can be placed to within 1/4" accuracy on the bed image before printing.

If that alignment shifts when using “auto focus” vs. manual material thickness, then the calibration is likely off and needs to be reset using the calibration process.

None of this has any effect on the actual focus height during printing. That is calibrated at the factory.

The only exception to all this is if your laser head is defective and the head camera is not determining material thickness correctly (out of calibration), in which case the machine would need to be repaired or replaced.

Yep, and just double checked.

Well, if my auto-focus is wrong, that would also throw off the alignment, too, wouldn’t it? So the calibration process might not help?

Yes. I pointed out the calibration process is strictly for alignment and has no effect on print focus height. It should correct the shift you see (unless the head is defective.)

I assumed your primary issue was the change in cut and score between manual vs. auto focus height. Running the calibration will have no impact.

Thanks, makes sense :+1:

1 Like

So, to sum up… Seems like I’m in super deep trouble :sob:

As the actual “measured focus height” is unknown (not displayed), I think coming up with some repeatable evidence of differences between auto vs. manual focus height would help speed things up.

I see you already emailed us about this and we’re working on it there, so I’m going to close this topic.