Unable to get a clean burn using rotary and powder-coated tumblers

I have been working with support on this issue, but the process is slow and long. Appreciate any advice I can receive.

I’ve transition from the LM2 to the LM2Pro LF and I cannot get the Pro to cleanly burn a powder-coated tumbler. Support originally thought it was a focus issue. I have adjusted my focus by 1.6mm (51.6) and it is better. But as you can tell by the attached picture, there is still an issue. The latest discussion was a question as to whether or not I had changed the firmware’s $33 setting (frequency). He said it should be set to 1000. I have not (nor do I know how) changed any settings. In fact, I updated the firmware of the device after I received it in January and recently reinstalled Lightburn as I was afraid there could be settings in it associated with my LM2. I have changed the homing machine settings since I am using a rotary. I have also removed the air assist as there was a concern that it was not allowing me to focus properly.

Very open to advice. My LM2 burned these tumblers beautifully. I would expect the same with the Pro.
20220330 Firmware
Closeup on burn

I have confirmed that $33=1000

What is it about the burn that you’re finding unacceptable? Is it the visible dots or something else?

Do you have a sample of something burned with the LM2?

Can you share a sample .lbrn file to review settings?

The issue is the it’s not a clean burn due to the lines and dots. In one of my attached pictures, you can see it doesn’t even burn consistently to the edges of the letter.
1 Comparison between LM2 and LM2Pro with the burn settings listed
2 Lightburn default file that I use for all my burns.
3 Picture that shows the result of use the default file and default focus on the LM2Pro
4 Burn test that Ortur had me run on wood which indicated to them the laser was firing correctly.

Etsy Shipps - Hendrix Sm.lbrn (119.7 KB)

Okay, thanks for the extra detail. I can understand your take on the difference.

Well, you can even see vertical banding in the test which I assume is related to the issues you’re seeing in the power coat.

When you focused the LM2, did you focus on the surface of the material? Or somewhere else? How does this compare to what you’re doing for LU2?

Is your LU1-4 fixed focus or variable focus?

Only a few things that come to mind about what might be going on.

  1. The lens LF lens might have a smaller focus dot than LU1-4. You might want to consider further defocusing to see if you can even out the envraving
  2. Have you tried adjusting DPI settings at all? You may want to run an interval test to see what the best setting for your laser and material are
  3. Have you tried burning any other types of materials without the rotary? Do you see any other artifacts when you burn those things?

I’m curious if you could swap the LU1-4 lens into the LU2-4…

Ortur said I could not swap the lenses because the voltage was different.

  1. I have seen improvement in defocusing - greater focus rather than small focus. Best to date is 51.6mm rather than the 50mm default. The image with the “B” is with the 51.6.
  2. Haven’t tried changing DPI - I will! Curious as to why it have different results between the two.
    3 Wood cuts well, engraves OK. I see the same lines, but it’s not near as noticeable as it is in the powder coated materials.

I didn’t answer your focus question.

LM2 - default 30mm focus measured from bottom of lens to the material surface
LM2Pro - default 50mm (although I have been adjusting this) from the bottom of the module

Don’t see how that would make sense but maybe they’re referring to the modules being sufficiently different.

I assume the biggest difference is going to be in the focus dot shape+size and realized power based on that. It’s possible that the LU2 is being driven harder as well but not certain about that. It’s possible that you would have better luck with the SF lens but I feel like you should be able to get similar results defocusing + DPI changes. You might want to try getting closer than the focal length as well.

I agree. I can’t wrap my mind around that unless it requires different voltage settings from the motherboard to drive the power levels.

I’m about done with this laser. Last tests.
Removed the rotary to eliminate one variable - everything done on a flat surface. Tests run with different line intervals/dpi settings and focal settings. Best results are focus of 51.6mm with 254dpi/0.1 line interval. Still not to the quality I’m use to or provide to a customer. (The picture with the letter B is with that setting).

That’s really unfortunate. Time for a downgrade?

I am having this same issue with my LM2Pro LF. Did you ever figure out a solution?

1 Like