I did some quick tests with titanium. Not sure of the exact alloy this one is as I got some from a friend of a friend, but it looks promising I did 3 tries of my grey scale map to see how they’d do.
Starting with the lightest on the far right where I used minimum power and maximum speed which was way too light, I tried increasing power for the second one and then I reduced speed as well for the third which really started to look good. The interesting thing about titanium is that you don’t need to coat it in anything to mark it like this. For other metals you’d need a metal marking compound on them, but this was just putting the metal in the Glowforge and “etching” on it. The most curious part to me is the 100% in the top left corner. Really the text tags and that top block were all 100% black in the bitmap, but the square turned out blue while the text is black.
It’s probably related to how much area the heat is being applied to in a certain amount of time, but I’m sure it’d be interesting to use this somehow to do multi color prints.
@dan Is that advisable? Aren’t there reflection risks with any metal or reflective surface that might damage the diode lense or refract in unpredictable ways?
Just wondering…
We can’t give advice on materials we don’t provide, I’m afraid. We’re working on a mechanism for people to share information on materials they get from other sources.
Unfortunately this is a place where lawyers have strong opinions - related to why we don’t discuss safety issues on the forum.
Safety issues have been discussed on numerous occasions on this forum, including comment by GF if my memory serves me correctly (?)
Regarding metal, we have in the past marked metal objects after they have been processed by other means (laser, milling etc). So marking is typically the last stage. Even if GF makes metal ‘proofgrade’ we won’t import it since it would be prohibitively expensive. My point is that metal marking is a category of its own and I would imagine many users would be interested in metal marking with their GF.
It would not seem right for GF not to offer advice on materials just because we don’t buy them from you. For instance, if I understand correctly, the GF uses a custom tube. So at least ‘some’ guidelines would be required regarding usage of common laserable / markable materials.
By all means, add your ‘friendly neighborhood laywers’ 3000 word disclaimer. But don’t leave us out in the cold on usage guidelines for common materials just because you don’t provide those materials.
On a normal machine with a metal nozzle around the lens I expect there is little chance of damaging it. On GF with plastic bits closer to the work piece than the lens it could be more of a problem. Perhaps the bottom of the head should be covered in foil.
Having said that just because something reflects light is no indication whether it reflects far IR. If it cuts or marks well then a significant amount of power is being absorbed.
And, of course, unless something gets warped, the stuff coming back is spread over (at least) the entire aperture. So you’ll get heating problems and potentially feedback problems but not cutting. There was a earlier thread on marking titanium than involved melting pits in a laser-cutter lid, but that took a lot of work.
titanium is put in lasers all the time, so unless it’s polished i’m guessing you’ll be fine - as with anything, however, proceed at your own risk.
with that said! i’ve seen people play with the color spread fairly often; depending on the titanium and laser, you can get a whole host of colors coming out. from what i recall, fiber lasers tend to do a better job at this aspect, but you can get several shades of unique and uniform hues from a co2 laser alone.
as i understand it, the colors are formed because you’re creating controlled oxidation on the surface of the metal. you end up with a blend of titanium oxides - TiO, TiO2, Ti2O, and Ti2O3 - but the specific oxide matrix depends on precisely how, where, and when you apply the energy.
edit: here’s an interesting paper talking about taking advantage of this process for coloring jewelry. note their use of a pulsed Nd:YAG laser, though:
I agree, based on Hirudin’s experiments the marking went fine, but when trying to cut by repeated runs over the same line, bad things happened. I don’t know if that was general diffuse reflected power, or if by cutting the trench he got, in effect he started to have a mirror that resulted in much more focused light being reflected.
Not sure what his laser head was made from, but all the electronics and other goodies in the gf head may pose a higher risk for damage.
I hope we will see some info on how safe vector and raster markings will be as these are some wonderful effects.
I think a flat mirror at the focal point would reflect a cone that expands back to the original beam width when it hits the lens. The GF aperture is the full size of the lens, so much bigger.
If I am reading this right, you colored the Ti with the laser?
If that’s the case, my bet is that it would do it with any reactive metal. Niobium being the next most common, and what I work with the most. I was actually thinking of a similar idea last week. Just waiting on my matching to test.
Yes. Titanium (and niobium, which is what I work with more) are reactive metals, so when exposed to electricity (and it would seem a laser, though I readily admit I have NO clue how it works with a laser) they “react” and build levels of titanium (or niobium) oxide. The thickness of that oxide layer determines what color you see. I’ve never done this in a laser, but I’m itching too. There are a LOT more colors you can get on niobium vs titanium, and they tend to be more vibrant, but both are fun to work with.
We do it in an electrical bath. Specific voltages of electricity give us very predictable colors. I have some ideas I’ve been dying to try, and his test told me my idea is at least plausible.
I did 3 tries of my grey scale map to see how they’d do.
