Mirror Focus Issue?

Hi everyone,
I work in a public library makerspace so a lot of hands touch this CO2 laser cutter. It’s a blue box Chinese knockoff brand that has been here longer than me. I’ve spent the day trying to get it aligned and I’m making huge progress. When I started, it would not cut 1/8 wood at full power and it’s a 60 watt laser. It had numerous issues. I’ve dialed it in except that as you can see from the picture, I still get this weird shadow along the cut line despite having auto-focused it. Can anyone look at this picture and give me some advice? Do you see anything obvious?

focuslaserissue.lbrn2 (93.3 KB)

thank you for any help you can provide me on my never-ending aligning the mirrors journey. :slight_smile:

I don’t have an answer to your existing problem, but would like to present a careful observation about the power setting. Your tube may not be a true 60 Watt. You can measure the diameter and length and find a reference online to present the real rated power.

The other aspect to consider is that it is recommend to never drive your tube to 100% as it will drastically reduce the lifespan of the laser. My 60W is a true 60W because I replaced the shipped tube when it failed. The new true 60W tube was about 300 mm longer than the installed tube and my research showed that it was about 45W. I’ve lost the bookmark that provides the correct power ratings and also the recommended maximum current for each tube.

This brings to my alleged mind that the laser should also have an analog ammeter connected to the output/ground wire of the laser tube. This allows you to match the in-use current draw with the recommended maximum. My 60W tube is good to 65 percent power which is approximately 28 milliamps, if I remember correctly.

Directly on point of your problem, you may be getting nozzle reflections. Ensure that the beam is traveling straight from the last mirror through the nozzle. The lens should be placed with the flat side pointing to the work, curved side up.

1 Like

If the machine has these three it will work

  1. Properly operating tube
  2. aligned and clean optical path
  3. proper focus

Obviously it’s one of these. By the look of your ‘example’ I’d suggest doing a resonance test for TEM0. The output being offset like it is and does have a change of where it’s occuing on your engraving seems to point towards a tube issue. It’s easy to check and eliminate.

If the beam output of the tube is not TEM0, it needs to be replaced…

Do you know the time this tube been used? The Ruida maintains this if it hasn’t been changed out before.

When you do the ‘burn’ make it as light as possible to see the pattern. A black hole tells us little. Hopefully a maximum darkness of brown… You are looking at the power distribution across the beam.


Moved to #hardware

With an unknown past, my suggestion is to check the lens and the nozzle in the head.

If the nozzle is heating, the laser could be touching it at the outlet. The light could bounce around and make the artifact in the wood.

Unusual debris or smoke build up could be a contributor.

A damaged or poorly assembled lens (again unknown past) could be responsible for the artifact.

This topic was automatically closed 30 days after the last reply. New replies are no longer allowed.