Marks/Bumps from Laser Refracting off Honeycomb Laser Bed (is that a thing?)

It’s all right and you are welcome, I enjoy working and experimenting with my laser a lot, so it fits well together :wink:
Yes, the small elongated square and the rest of what is shown are made with the relatively fast speeds. It can also be made faster, but I feel best with these settings for 3mm acrylic.
Kerf, even though it should be easy, I also sometimes scrap parts because I think “reverse” once in a while. As recently as today, I had to do some intarsia work and also chose + instead of -, but that was only a small topic for my own pleasure :wink:

It is 3mm BB plywood and the LB monster :wink: is made of mahoni veneer.
Kerf is only assigned to the dark part, - 0.1mm

That’s genius, I’ll give the steel sheet another try with some magnets then. Thanks for the heads up!

I whipped up some acrylic standoffs and now have my material roughly 13mm above the bed. Better results but it would seem I need to go higher, still getting some reflection over a few different areas of the bed. I’ve leveled the the cutting area meticulously at this point and my standoffs hold the material level. I’ll assume some parts of mesh are just more reflective than others.

I can see the appeal of having options for honeycomb, aluminum slats, and steel sheet as a contributor previously mentioned. I need parts of all sizes cut so it’ll be great have each bed style dialed in.

I’m 5mm off the bed and I don’t have these issues…

If it’s going through, it is not very focused coming out. It travels another 13mm to the bed, becoming more spread out, then bounces off the whatever, travels another 13mm back up, more power loss… and burns the material…?

Maybe a ‘wee’ bit too much power…?

You need to slow down and think about what’s going on here…

Place the magnets so they are not struck by the beam… The bigger magnets are used to make a crude side/top stop ‘frame’ for the material.

If the reflection is doing damage, a part, not falling perfectly will be toast if it’s hit. One of the reasons that I keep it close to the bed. I usually get a pretty good ‘stream’ of debris gas out the back.

What doesn’t go out the ventilation, pretty much sticks to the steel plate.

Good luck

:smile_cat:

Okay, interesting. Overpowering could be the issue. Maybe I interpreted it incorrectly but from what I gathered through Russ’s tutorials was to bring slower speed and more power to the cut. That said, he used mostly 5mm acrylic. He also mentioned 3mm being much more difficult to get polished due to the lower heat/gas reaction polishing effect that takes place with thinner acrylic.

Regarding reflection - Maybe I grabbed the wrong sheet? What I got was a flattened sheet of cold rolled steel. Don’t recall the gauge atm. The sheet is definitely shiny which made me question its ability do what I needed it to do. You mentioned the steel being dirty, dark, with smoke sticking to it so as to not reflect back up. Is that similar to a cast iron pan? I mean, does the sheen in the metal need to gain a sort of seasoned coating from smoke before it stops reflecting? Trying to think of ways I’d be a le to dullen the sheen… Sorry for the rapid fire of questions, genuinely confused with the steel sheet reflection topic.

In terms of power level - I haven’t really tested above 40% So far my best results came from 3mm per sec @ 30% power (10ma from what I noticed) with a distance of 13m between bed and material + focal length of about 13mm. Would going lower be better? The lowest setting I’ve tested was 3mm @ 20% but it wasn’t quite enough to cut through. Could this possibly be a matter of some sort of hardware issue?

Thank you kindly for your time and consideration!

That looks pretty awesome :ok_hand: Love the idea of inlay.

Do you design solely in lightburn?

I think you can see how dark it is in the picture. I went to the local steel company with my measurements and asked them for ‘rolled steel’. It has always been relatively dark.

Remember, even the beam gets larger in diameter as the distance increases. This is exacerbated by the lens itself. Once it passes the focal point it will start widening. As it widens the power density spreads across the larger beam. If it reflects, a very small area will probably reflect and it has no ‘flat’ or focusing ability, so the reflected beam is scattered, weakened even more. This happens relatively quickly. If it didn’t you wouldn’t have to be so precise in focusing. The real power of the laser is the lens focusing the beam to the smallest spot.

I use high power, like in the 70% or greater and run as fast as I can, especially with thin material. Don’t remember off hand, but seems like the cutting speeds are around 7mm/s for 4mm and 3mm/s for 6mm @ 70% or about 16mA.

Just try to pick up as much as you can. You will develop ‘what works for you’, in time.

Take care, good luck

:smile_cat:

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Everything is made in LightBurn and the dragon itself is of course our everyone’s little pet from LightBurn :wink:
Sometimes when I want to find the limits of the materials, the machine and my own ability, I make these marqueterie / intarsia. Here at last I make them as about 40mm coins, the youngest kids of the whole family love them.
In fact, it is also a nice kerf test, everything is just pressed together no glue. (Saturn is not inlay)

It is a thing. I actually cut 20mmX20mm for squares of 1/8" or 3mm birch hobby ply and elevated my work piece off the honeycomb, though the rolled steel suggestion by Jack Wilborn is a much better solution.

I just use golf spikes, the threads fall perfectly into my honeycomb holes.

image

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I don’t know if this is helpful at all, but I found that the powder-coated surface of the steel tray under my honeycomb was getting burned off by my laser (through the honeycomb), so I had the “bright” idea of adding a layer of aluminium foil over it, to prevent the beam from ablating the coating. I figured it would be fine with the matte side up. It was not. It bounced the beam back up to the underside of my piece and I got a bunch of wiggly lines and a scorchy gross mess all over it.

So I took the foil off again… and I just kinda deal with it… But maybe you could paint your steel sheet with something benign, to reduce the reflection?

If this worked, you could engrave aluminum… :wink:


For co2 machines, people use something that absorbs the emf, such as acrylic. Same idea for any laser…

The problem with any support that doesn’t absorb the emf, is that some of the energy will transfer to the material at the area of contact…

It’s tough to change that with a honeycomb bed or just v-shaped supports… I swapped mine out for rolled steel sheet… It still requires supports but makes for good air flow control…

:smile_cat: