Laser engraving on anodized aluminium

I am attempting to print QR codes on anodized aluminium cards. My first attempt was successful but subsequent attempts failed. Not quite sure how to diagnose what the issue is here.
Attached is a image of the successful run and then an example of a failed run.

Hi David,
Can you tell us the machine you are using, the version of LightBurn, your O/S and whether you did any software updates between the two?

Also, what version of the firmware are you using?

Hi There

I am using the Emblaser 2 SerialNo:E2-02344 Nov 2020 Rev.2
Light burn version:1.2.04
Firmware version:
OS: Windows 10 pro.
Most likely there were some windows updates that have occurred since install lightburn and firmware updates.


Could this be a Lens issue as I can see some degradation/markings on the lens.

Hi David,

Can you please go to the Device settings in LightBurn and check if ‘GCode Clustering’ is ON?
If it is not, please try enabling this then re-running the same program and let me know how you go.

Hi Lliam.
It was disabled, I enabled it but had no effect.
Here is an image of the lens. It appears to be marked.

I have noticed that during the job, the laser completely cuts out (no laser light) and then intermittently comes back on. (The red lid light stays on). Anyway, should we replace the lens?


Hi David,

The Focus Lens should defiantly be cleaned.

If you can not get the Lens clean with a lens tissue or lens cleaning pen, you can use acetone and a cotton tip, followed by a dry cotton tip - this will cleaned all but the most ‘baked-on’ marks off the Quartz Focus Lens (The 2 part glass Focus Lenses are easier to damage).

Following this please attempt running a Focus Calibration - if any of the lines are intermittent or missing, please send an image of the front and back of the resulting card to

Otherwise, please try engraving a solid square (approx 25x25mm) in the same location in the workspace as the QR job - again, if any parts of the square are intermittent or missing, please send an image to

If neither test shows anything remarkable, please let me know.

Thanks Lliam
Did all of the above.
Seems to be working fine now.


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