The 15-Year Tube Secret: Why 0.05mm Interval is a Trap and 'Focus Down' is King

Community Laser Talk
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Hello LightBurn Community,

I’ve been in the laser business for 15 years, operating a workshop that serves global brands and high-end corporate clients. I see a lot of “academic” advice on these forums—people telling beginners to use 0.05mm intervals and “Defocus UP” (moving the head away from the material) for quality.

After 15 years at the machine, I can tell you: Most of this advice is a waste of time and hardware.

1. The “Focus Down” Revolution (Stop Painting, Start Sealing) Most operators move the laser head AWAY (Defocus Up) because they want to “blur” the beam to hide scan lines. This is the amateur way. It turns your beam into a weak, undisciplined fog. It burns the surface, but it has no “soul.”

My Protocol: I move the head CLOSER (Focus Down) to the material. Think about it: Why do you move the focus down when you’re doing a second pass on a thick cut? Because you want the “sweet spot” of the energy to stay inside the material. I apply the same logic to engraving. By focusing into the wood, I discipline the beam. It doesn’t just char the surface; it creates a deep, caramelized, tactile “seal.” When you touch the engraving, you feel the depth. If you can’t feel the depth, you’re not engraving—you’re just painting with light.

2. The 2mm Interval & The 30-Second Miracle With the right Focus Down offset, I use an Interval of 2mm.

  • The Math: While others are waiting 4 minutes for a logo at 0.05mm, I finish the same job in 25-30 seconds.
  • The “Brush Effect”: Because I focus down, the beam acts like a wide, energized brush. The scan lines don’t “show”—they blend into a velvet-like texture.

3. The 15-Year Life Span of My CO2 Tube People ask me how my tube has lasted 15 years. It’s simple: Firing time. Every second your laser fires, it dies a little. By finishing my jobs in 30 seconds instead of 4 minutes, I’ve saved my tube from millions of unnecessary firings. I’m not just saving time; I’m saving thousands of dollars in hardware.

4. My “Master’s Sequence” for Settings: If your logo is too light (white), don’t touch the interval!

  • First: Push the Power (e.g., from 85% to 95%).
  • Second: If power isn’t enough, drop the Speed (e.g., from 200 to 150).
  • Last Resort: Only then, tighten the interval.

Proof: Check the attached photo. This was finished in seconds. It is deep, clean, and has that perfect “Master’s Brown” color.

Don’t argue with theory. Don’t argue with manuals. Argue with my results. If you don’t believe me, go to your machine right now, drop your focus 2-3mm into the wood, open your interval to 1.5mm or 2mm, and see the magic for yourself.

Lazerli Baski - Murat Kor

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lazer baskı türkiye

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…sounds like you’ve invented the deep dish, congratulations on that.

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Oddly enough, I think these “Hints” can apply to diode lasers as well.

Unfortunately, my clients prefer deep (0.5mm - 1mm) etchings that are black for contrast, so a “Master’s Brown” would not be acceptable. They said when it is not dark, it looks like it is printed or stamped, and not really “laser”.

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"Nice to meet you, Mike! However, there is a clear distinction between a hobbyist workshop and industrial production. My protocol is specifically designed for high-end Industrial CO2 systems, not for DIY Diode/GRBL setups.

After 15 years in this business, I’ve learned that professional clients prioritize the overall aesthetic, price, and delivery time over microscopic details. But of course, the customer is always right!

If you were my client and insisted on that specific deep etching, I would charge you $2 for a job that normally costs $0.25. Because in a professional workshop, that extra processing time has a specific cost. )) Cheers!"

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[quote=“lazerlibaski.com, post:6, topic:188738, full:true”]
I see your point, Mike! Customer preference is always the final word. If your clients specifically look for that deep, charred black look to feel the ‘laser touch,’ then that’s the standard for your market.

I see your point, Bernd! Customer preference is always the final word. If your clients specifically look for that deep, charred black look to feel the ‘laser touch,’ then that’s the standard for your market.

In the high-volume industrial sector where I operate, we focus on speed and preserving the machine’s lifespan while achieving a clean, professional aesthetic. But as you said, ‘Master’s Brown’ or ‘Deep Black’—at the end of the day, we both work to make the customer happy. Cheers! ))

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All my etchings are 1-pass runs. It should still cost $0.25 if all I vary is power, right?

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It was definitely not meant to insult a living person and I unfortunately assume that what you wrote was AI generated.
Thanks for the information, but as you write you are probably a different ballgame than the rest of us and the only one I have heard of who could run a CO2 glass tube for 15+ years, it is remarkable.
As for your examples, I can’t see anything extra ordinary in it. Defocusing is a well-known and often used technique that most people use in their daily laser production.
I hope I haven’t scared you and you will continue to share your experiences.

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FWIW

I’m only into this a little more than I few months and I do this not only as a hobby but to keep my brain occupied.

I have a 10w diode that doesn’t have an auto-focus, so if I need to change the focus I need to do it by hand. The problem is if I touch the laser in the middle of a run the artwork won’t align. (Believe me I tried)

One time, when I first started, I had the laser focused for a different material and I forgot to refocus it for the new material I was planning to work on and engrave.

The result was the laser was defocused up by 2mm and the engraving looked better. My first thoughts were the manufacturer of the laser was wrong on what the focal length should be, or there was a problem with my laser. I quickly learned that defocusing was a common thing to do and I accidentally found the sweet spot for engraving.

The files I create involve both engraving and cutting, and since I can’t touch the laser to refocus I needed to come up with something that would work.

My solution was to focus down 2mm so the cuts would go all the way through and live with that for engraving and just change the settings.

The final result was the engraving looked even better.

Thank you for confirming that my solution makes sense to someone else besides me.

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The problem you describe should be able to be avoided with an arrangement where your material cannot move, at all. The laser head itself must be so well constructed that it does not move the focus by changing the focal height. On CO2 machines (most) we have the advantage that we raise and lower the material with the machine bed and not the laser itself. But as I said, it should be possible to adjust the focus length, also on a diode laser, it worked here for me. With that in order, you just have to divide the job into different layers and then there is a good possibility of adjusting (defocusing) the laser.
The thing about forgetting to set the focus back to “0” - we have all tried it and still do it every now and then :wink:

The picture shows a defocus with 4mm, Multilayer, Cross-Hatch 90 degrees and LI of 0.35mm and a round of line with the same power and speed (12% 200mm/s)

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Thanks for your input

Done

You got me there, are you saying the laser’s position? If not, how do you change the focus height by not changing the focus?

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To focus I have to turn two screws, one on each side, to adjust the focal length.
If the laser moves as little as 0.05mm it’s noticable

Indeed, that’s how I engrave and cut the same file.

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Same focal length using different power and speed settings on 3 different layers

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Set GRBL parameter $1=255 to lock the drive motors in place.

I had the same issue with my S30 Pro until I bought an adjustable mount for the laser module.

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That’s what I was afraid of. Of course the laser changes position when changing focus, but it must and should only change in the Z direction, not in X or Y.
If you don’t have the ability to “engineer” your way out of it, you have no chance. On my old Eleksmaker I tightened/locked the screws from one side and only loosened/tightened the screws on the other side of the laser head to adjust the height. It was a little tight but worked in return.
0.05 mm is not much but enough that the result (cannot) be good enough, for example I use 0.075 mm for press fit for mounting MDF connection, 0.05 mm error will make fits useless for my purpose.

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This was mentioned to me in this post. Since my laser doesn’t have limit switches I didn’t get consistent results. Thanks for the reminder.
-Is there a way to lock the laser head in it's position? - #4 by ednisley

Interesting, is this mount generic that can be used on any laser? Do you have a link that you can share?

But I did, in case you missed it

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No, the mounting holes are specific to the Sculpfun S30 laser.

Google “Z axis adjuster for sculpfun s30 laser”, but insert your brand and model. I would have Googled for yours, but you did not say which you had. When asking for help, it often benefits to know.

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Found it on Amazon, thanks

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If that’s your solution, then you’ve “just” found the optimal focus point that best fits your needs. The only downside, however, is that with plus or minus 2mm you no longer have your smallest spot size. But as I understand it, that’s not the most important thing for you.

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Thanks - I just ordered one for my OLM3 10 watt diode laser. At only $25 it’s on order.

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Great! Not sure how yours is made, but if I use the original adjustment screws, I get about about 4” adjustment range. I replaced the original adjustment screws with knob screws.

In retrospect, I should have ordered the knob instead of screw adjust version Z-adjust.

Post a picture when you get it installed. :nerd_face:

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I am newer to the laser world - I’ve read this over a few times and am still trying to process this, I apologize for the lack of understanding.

If you are putting your line interval at 1.5mm to 2mm on say a 1/4” square, that leaves about 4 passes back and forth to be completed. As opposed to what I have been using on average at 0.07mm which has a bunch and obviously would take a bit longer to engrave. I’m not understanding how I can get the same look with 4 passes compared to several. I’m not fully understanding how to “Focus Down” either so that doesn’t help me lol

I will test this of course; I am just having trouble understanding this all. Now, of course I dont know what laser you are using and all but just based off of how ours is set up (not meant for this kind of thing, usually used to cut out fabric templates) but we have been dabbling in it and Im trying to get it dialed in as much as possible.

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Once you can mentally visualize the image of a laser beam, it becomes easier to understand.
I’ll leave just an image for better understanding.
This is from laser cutters but it looks the same:

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