Adventures in Anodized Aluminium

Could you make a stencil to apply on the YETI, apply Cermark, remove stencil, and hit it with a blow torch?

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I guess copper is an almost perfect mirror for the infrared wavelength, which would endanger the lens.

By chance, would you mind sharing the settings you used? :slight_smile:

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Huh! I missed this one! Great job on the tags @dwardio ! :sunglasses::+1:

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Those were engraved at 10 pews, 335 zooms, and 340 lpi, however that was on my PRU over 6 months ago – all settings have changed since then. That being said, those wouldn’t be terrible settings to start with on a test blank, most likely upping the power to compensate for the new low-end power settings. :wink:

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Very cool, and thank you! I had good luck with power of 60, speed of maxed., and lpi cranked to second from the top.

I also made a gradient test, and found an interesting pattern of increasing anodizing removal from minimum power up to around 40%, then a patch of what looked like bare metal between 40 and 60% power, then essentially white (oxidized?) above 60% power.

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Can I ask a quick question:

What does Pew, Zoom, LPI, and PRU mean?

I found this post Glossary of abbreviations, acronyms, and initialisms in wiki , but it doesn’t have those terms defined.

Sorry about that… Two common GF nicknames: pews=power and zooms=speed.

LPI = lines per inch (vertical resolution)

PRU = Pre-release Unit – Glowforges that were produced between beta and final production. Any settings that mention PRU should be taken with a grain of salt, as all settings have changed in production. With testing, they can be a good starting point…

Hope this helps!

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Absolutely, that is very helpful.

Also, when people write things like 100/300/340 I assume they are saying pews/zooms/lpi?

Yes, exactly. Occasionally there is a 4th parameter, too: 1, 2, or 3 passes.

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Ah ha!

Thanks for all the info.

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Isn’t the order different now than it used to be…ie speed, power, LPI? It used to have power listed first, then speed.

would translate as power/pews 100, speed /zooms 300…but that would be backwards from the correct settings. Everyone that notes settings like that must know that the first number is speed, not power. Seems it could confuse some.

Ha ha…clear as mud?

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All of the anodized aluminum I’ve done has been at 1000/100/340. I haven’t found any reason to drop speed at all.

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@Tom_A , since it seems like you have done a fair bit of anodized aluminum, could you answer a question ive been trying to look up for a week to no avail?

I have read 3 different things about engraving on anodized aluminum, and I cannot seem to confirm one as correct yet.

When you use the Glowforge on the aluminum, lets say with your 1000/100/340 settings, are you:

a) bleaching out the color of the dye (but doing nothing to the anodized layer itself, and no dye is removed, just accelerating the natural effects of "sun bleaching"
b) removing the anodized layer of oxidation entirely (showing bare metal in the engraved locations)
c) removing anodized layer to some extent, and vaporizing/subliming the dye as well?

Basically, I am just trying to determine safety levels and precautions. I live in a 1 bedroom apartment, and my Glowforge is about 5 feet from my couch and 5 feet from my kitchen. So far I have not touched any material besides paper and proofgrade plywoods and hardwoods, for fear of all the wood particles that I see all over the inside of my machine being something a bit less natural (like acrylic or metal). I know I have read that the aluminum itself does not get sublimed by the laser, since the CO2 laser is just not powerful enough to engrave into the metal, but some places make it sound like the CO2 laser will engrave into the anodized layer, and others make it sound like its merely reacting with the dyes and that even the anodized layer is too strong to be sublimed by a 40W laser. I just want to make sure I know what to expect when I start doing materials other than wood and anodized aluminum sheets, dog tags, cards, etc are very high on my list that I would like to try next.

Thanks for any information you can provide (or anyone else for that matter) and especially if you can point me to any documentation or articles or anything that would be good reading for how this all works and how to stay safe with this (since most of this is usually done in a shop, not a living room, and so none of what I have found is written with that sort of environment in mind…a shop has a reasonable expectation of some risk/dust/etc, and usually has a much more industrial ventilation system than the GF has.

Cheers! And Happy New Year!

I believe (no documented sources for you - just experiential insight) that it is burning away part or all of the anodization layer. Aluminum dogtags and business cards are my current classes practical exercise before we let them loose on the laser so I’ve been doing a fair amount of it.

The reasoning for my position is that if it were simply bleaching the dye, there’d be no perceptible physical change to the material surface. But what I find is that something is being ablated as the fingernail test will allow you to feel the engrave. There is some delta between the un-engraved surface and the engrave.

Now I don’t think it etches the metal itself - just removes the anodization on the aluminum I use. The reason for that conclusion is because I have not noticed any further oxidation of the aluminum even after a couple of years - no fuzzy white oxidation occuring. However the natural state of aluminum is to have a thin oxidation layer that generally protects it from continued oxidation. That’s why you don’t get serious aluminum corrosion except with some aggressive oxidizer (other than air) or electro-chemical reaction. But that explains why engravings dull a bit and then stabilize.

So the anodization layer is ablated and the resulting exposed aluminum surface oxidizes to the point it is protected from further oxidization and then stops.

Now that’s all in relation to commonly available aluminum materials used for engraving - there are many aluminum alloys and their reactions to CO2 lasering might be very different.

@takitus might have some technical sources he could point to as the resident physicist here.

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You narrow that down a lot with anodizing. Most aluminum that is anodized is in the 6000 series. I use a 5000 series for most of what I anodize. Most of the others just don’t anodize well, or at all.

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Exactly correct, as noted all aluminum develops it own natural oxide layer. I found a link to anodizing information on Wikipedia:

Anodizing - Wikipedia

So do you notice a fine dust of anodized layer (whatever color) when you do a lot of dogtags? Or is it so little that comes off that you never notice that buildup? Thanks for the help, I am a hypochondriac, and the promotional video 2 years ago definitely sold me on the safety of the GF, which was a bit overstated, since many of the materials it can engrave are still toxic to engrave and require a lot more precaution than just plug and play.

That. Lots more residue is noticeable from MDF (including PG Draftboard & PG Plywood cores).

As long as it’s vented outside you shouldn’t have any health issues - sensitivities to odors may be different because lasers can’t be totally sealed (at least not without a couple more zeroes in the price).

Sorry to beat the dead horse, but I just want to make sure I understand entirely before I do it lol.

With engraving acrylic (I’ve never done it but I’ve seen pictures) and plywood or hardwood, there is a fine dust that gets everywhere inside the machine and needs to be cleaned out (the fans push it around and some out, but lots get deposited on the bulb, front lid, glass lid, floor of the machine, etc.

You are saying that the layer removed of the anodized aluminum is so minimal, you’ve never noticed any colored anodized layer dust in your machine, deposited on the floor, walls, moving parts etc? Thanks again for your response!