I learned a new word. Didn’t know anodized just meant ‘coated’ and not some form of manufacturing the metal. 
4 Likes
Yes and yes 
Funny how skills cross seemingly unrelated fields 
His mother may forgive him for his ink.
You know you can buy display models of most phones and tablets for $3-$12 a piece, right? I have to buy them for work to use as photo props.
13 Likes
True enough but after hundreds (thousands?) of hours using this one, it never crossed my mind that it would go amok. However, since I was standing watching, if it had gone close I could have just popped the lid and the laser wouldn’t fire (interlock).
The one I’m hesitant on is the Surface. It’s got a magnesium shell. While I’m certain I can’t cut it, I’m less certain that it won’t catch on fire. Magnesium burns. A lot. And hot. And fast. Underwater even. I don’t know if the vapor-deposition process they use to make it alters that characteristic of the base metal but I’m hesitant to try.
In the absence of a Class D extinguisher (which I don’t necessarily want to have to be spraying all over the innards of my laser) the best option is to “stand back from the fire”. Water can be used to cool it and keep other stuff nearby from catching on fire but CO2 extinguishers allow it to turn into the equivalent of metallic napalm.
I’m saving the experimentation until I get my GF. Then the K40 will be available for testing whether a Surface tablet can be safely engraved
3 Likes
Epilog lists magnesium as engravable with their fiber lasers, but not with CO2 lasers. So I guess the laser doesn’t set them on fire, but the CO2 laser doesn’t do much.
Burning magnesium is scary in any case, though!
2 Likes
I’m not sure if the finish on the Surface is native to the PVD process or something like an anodization layer or something like that which I could ablate off with the laser (like you can with powdercoated steel). But I’m not willing to try yet I need the GF so the K40 can be potentially sacrificed.
2 Likes
Yes, anodizing is an electro-chemical surface oxidation, which impedes further oxidation. The laser removes the surface oxide layer, not any metal. Aluminum oxide is also very hard, imparting a significant abrasion resistance compared to clean aluminum.
4 Likes
I did not! New eBay keywords, thank you. 
4 Likes
Died
2 Likes
The trick, iirc, is that aluminum oxide, aka alumina, is not only incredily hard (used as abrasive), it’s also roughly the same atomic/molecular size as aluminum metal, so that when you form a layer it sits tightly on the surface (as opposed to iron oxide, which is bigger than iron metal, hence the flaking). The usual self-protective layer is only a few atoms thick, but serious anodize (especially the colored kinds) can be thick enough that you have to allow for it when putting parts together.
5 Likes
I got anodized handle bar ends for my motorcycle one year. Have to think up a tiny design to go around the end hole.
3 Likes
@karaelena I have been trying to figure out if the laser actually removed to oxide layer or if it just bleached the dye. I am interested in doing multi color anodizing with the laser exposing clean al in between dips in the anodizing bath.
Do you have any insight into what the laser is doing?
7 Likes
Yeah that stuff they use for store front windows is bullet proof for any further oxidation.
IIR Alumina is a synthetic and runs around 3.5 on the Mohs, where Aluminum oxide is a solid 9. The only thing harder is diamond. Interesting that Mohs scale is not logarithmic, there is as much room between 9 and 10 as there is between 1 and 8.
I didn’t know the molecular bonding was so tight, that helps me understand why the oxide of such a soft metal is so hard. 
4 Likes
eBay has a whole section just for them. They are produced by companies as non functioning floor models for use in stores and as a side note, are a great way to practice replacing a cracked screen before taking a screwdriver to your actual phone.
15 Likes
You just gave me a great idea for a new business once my glowforge arrives: Glowforge Tattoo Removal and Alteration.
“Yeah, just stick your arm in that machine over there and let the laser do its thing. If it burns, that just means it’s working.”
14 Likes
For a temporary interim solution, one of those soldering re-work stations could cover up the tattoo’s with nice burn scars… 
4 Likes
Are all Ipads Anodized?
Yes, as are all Apple laptops and iPhones.
2 Likes
You’re my idol! 
3 Likes
This was enough to bring me out or hiding for a first post. I bought my GF for our business, and a big part of that is to engrave anodized aluminum. If it’s possible for me to be more excited than I was before, it’s because of this.
On a side note, if you want to play with doing more on AA, I’d be happy to send you some small, pretty unique parts to play with. They all have a small curve. Don’t need them back, don’t want anything in return, just an offer for you to try something different
21 Likes