Rear browning around edges of 1/4" maple through cutting

Community Laser Talk
1

Hey all.

I’m face engraving and the cutting through 1/4" soft maple thin boards. Using my 40 watt diode Falcon2 I’m engraving at 2500 mm/min at 25% and cutting through at 350 mm/min and 65%. I’m cutting on top of a steel 400mm x 400mm x ~25mm thick typical steel honeycomb support grid.

All is going well with the exception of some reflective brown surface burning I get on the backs of the parts right next to the cut through. These seem to align with the steel grid below. This all easily sands of in a few seconds but I’m doing hundreds of these parts so it would be nice to be able to eliminate the back sanding step.

I’ve cleaned by support grid and this still happens so its not just a matter of buildup residue on the grid causing the problem.

Any suggestions…or is this just simply to be expected.

Thanks,

BH

2

The typical solution is to elevate your material off the honeycomb grid on riser buttons, this will prevent the flashback from marking the back of your parts. You can DIY your own, or there are many options online for this sort of jig tool

3

DOH…LOL. Of course. Thank you. I’ll 3D print some this afternoon for use tomorrow.

Much appreciated.

BH

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4

If you can use a magnet your honeycomb, that’s usually about the best you can do, at low cost. If it’s made out of aluminum, it won’t work.

I use a solid sheet of steel, so, when cutting, there is air air flow on both sides. A honeycomb bed doesn’t really allow air flow.

Good luck.

:grinning_cat:

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I have my honeycomb lifted about 1/8" above my aluminum bottom protector plate. That allows at leasdt some air flow all around.

BH

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6

Could you also spray the steel sheet with high temperature engine paint.

7

If you hit one with the laser, it is toast (literally!).

Here is an alternative that looked promising…

8

Your link is why I don’t use honeycomb. Besides the fact it’s not usually really flat, they make most of them out of aluminum, non magnetic. If you laying a piece of material to do a non-cutting operation, there’s no difference between it and a sheet of metal. Except a sheet of metal will allow much better air flow as it doesn’t go down the honeycomb where you don’t have material. You almost need some type of blocking material to prevent the debris to go elsewhere.

You need to lift it so there is a place for the debris to go. On my machine, a number of dirty sub flooring that I cut, most of the debris sticks to the flat sheet or table, so I can wipe it off with a rag and solvent. You have to soak honeycomb to get in the holes. Even honeycomb doesn’t really work as the holes are limited to your air assist and it has to flow through the lasers kerf, which isn’t very wide.

Russ Sadler did a couple of videos on the dangers of honeycomb, might be worth a watch to see what happens on the underside. I cut paper on my steel sheet for targets using watercolor paper. I can’t really do this very well with the honeycomb. Both of these target acrylic, but any material you’re cutting will have very similar results.

First one is about 3 minutes, the second, if you’re still interested, is about 15 minutes, if I recall. Russ Sadler still uses a honeycomb bed… :wink:

In the end, it’s whatever works best for you. :man_shrugging:

:grinning_cat:

10

That says it all! When cutting, I use typically 4-20 passes depending on the material. Only the last pass or two does the smoke go downwards. A majority of the smoke is not in the honeycomb. To help with both conditions I have tiny scavenger fans inside the enclosure (images in other postings). That is what works for me. That is my story and I am sticking to it. :nerd_face:

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