Even with just the blue and yellow you could get some really neat effects with two tone art.
Thanks for taking the time and effort to do this.
I really appreciate it.
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Oops, I intended to only make it “unlisted”. I wondered why the thumbnail was a grey rectangle.
It should be fixed na. It’s only a few seconds long; I wanted to upload it directly to the forum, but I guess there is a 10MB limit to MP4 files.
@numosbk, This piece is approximately 3/16" (approximately 5mm) thick. I don’t think I have anything thinner.
@Clone, I think a buffing wheel would clean it up. I technically own one, I think, but I haven’t taken it out of the box yet. I bet a few minutes of sanding would clean it up, I’ll try that next.
Hey, this is exciting, both the colors achieved, and the engraving!
Can you remind me what the wattage of your laser is?
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'Tis 30 watts.
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HEY! thats the same as my 40 watt Chinese laser! 
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So it sounds as if TI foil is not entirely implausible to cut if you had a really good reason. Hmm.
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I just got on eBay and ordered some small pieces of titanium foil (0.5mm thick, 100mm square) from China to try out. They should apparently be here next month some time.
Thanks! I hadn’t considered that titanium foil “is a thing”, even though it makes perfect sense.
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There’s even a bunch on amazon. Btw, some of the large industrial suppliers sometimes let you have a few feet as a sample. Got about 10 or 20ft when I was getting my masters for free that way (was going to get the min $100 order, but by time the depth approved it they sold the spool…still send me the sample though…). Might have a little bit at home. It’s fairly thin (used as anneal bag to heat treat some high temp alloys)…
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Ti foil to save leftovers while backpacking. Saves weight over that heavy aluminum stuff 
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Cool! (I have some stainless foil that’s used similarly, but at lower temps. That stuff is sharp as the dickens, btw.)
Oh, and a quick gander at McMaster-Carr says this stuff is also available (possibly in a lower grade) as inch-denominated “shim stock”. Maybe for my birthday…
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I did another run of marking titanium, this time on an area that was sanded clean. The pattern is a little different this time; the top-left rectangle was 100% power. From there subsequent rectangles (by row) had the power reduced by 6.25 percentages points. This makes the left column 100%, 75%, 50%, and 25% power (from top to bottom). The lowest power, at 6.25%, is the bottom-right rectangle. The hand-written numbers are the engrave speeds (in mm/sec). All these tests were done a 1000 lines per inch with a pulse rate of 20kHz (I think) but I have no idea what effect changing this parameter would have (my guess: no effect). And as a reminder, this laser cutter is a 30 watt Trotec Speedy 100.
5 and 6 are only the bottom row of rectangles (25%, 18.75%, 12.5%, and 6.25%) run at 56 and 84mm/sec, respectively.
8 and 9 are only the top row of rectangles (100%, 93.75%, 87.5%, and 81.25%) all run at 560mm/sec. 9 is the same set of rectangles run twice with a small offset to see what effect “re-marking” would have. Not much happened, but maybe I should have run this one again at a different speed.
10 was defocused by 0.5mm (I moved the stock down half a millimeter making the laser beam 0.5mm longer).
11 was defocused by moving the stock down a total of 1mm.
12 was defocused by moving the stock up 0.5mm from the original focal distance.
I also tried 2mm down, 5mm up, and 10mm down. All of these resulted in the laser barely leaving a mark. I stopped these tests after the first rectangle or two and ran the next test at the same coordinates.
Separated image… (for clarity)
It looks like Discourse cropped this image in an odd way, if you click it a tall/skinny image should appear.
Original image…
I’m not sure what the quite-visible diagonal striations are but I’m thinking/hoping that they’re some kind of artifact of how the metal was manufactured.
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Very cool test, thanks for showing us!
It is interesting that the edges are different then the centers, as if the laser takes a little time to settle into whatever power level you set it on. My guess is that this is one of those things the GF folks had to figure out in designing their power supply.
It almost looks like the whole sheet was sanded diagonally, is that the case? might that have caused the visible striations somehow?
Also, I might have missed it, but do you know what alloy you are working with?
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The little stripes at the leading and trailing edges are interesting. I think you’re right about the laser taking a split second to settle into the proper power level. The software did each power level as a separate operation, so each rectangle was “engraved” on its own.
When I sanded it I basically just went randomly around the metal (back and forth, in circles, and in figure eights). I’m thinking the striations are either some kind of variation that’s actually in the metal or some kind of variation in the power delivery of the laser. (edit or variations in the speed of the head /edit) I should do one more test with the piece of metal at an angle to see what happens.
It’s 6al4v titanium, which I gather is also called “grade 5” sometimes.
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I think that stands for 6% Aluminum and 4% Vanadium. If you can find it you might want to try the Grade 1 or 2 Which are much purer and give brighter colors. They don’t machine as well though so if you are planning to fabricate something you are probably better off with what you have.
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I ordered some foil a while back. It’s coming straight from China I think so the expected delivery date is way up in the air. This stuff was pretty cheap, so I’m guessing it’s probably closer to pure titanium. I’m anxious to try it and I’ll be sure to post the results once I do.
Here’s the stuff I ordered… (grade 2 indeed)
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I had no idea it was possible to alloy aluminum and titanium, except maybe in zero G…
I wonder what working characteristics the aluminum contributes, perhaps it softens the brittleness of titanium? Vanadium also for that matter. I know it is used in steel for hardening.
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Titanium aluminide is a super alloy. They make ultrahigh pressure gas cylinders with it for space use. My understanding is that it can hold 4000 psi as compared to standard industrial cylinders at ~2500 psi.
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Wow! I imagine the alloy is more ductile than pure Ti.[quote=“volivaa, post:77, topic:2672”]
Titanium aluminide
[/quote]
Thanks for that! I shall have to read up on it.
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This is nothing so exotic.
6Al4V is the most common but there are quite a few other alloys as well.
I think all the alloy work is done either in a vacuum or under an inert shield gas, but other then that it is all pretty down to earth. 
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Thanks for that link! it’s exotic to me just because I was ignorant of all of it!
interesting range of properties across the alloys.
Ti6Al7Nb is the one I carry in my back because the 6A-4V is cytotoxic.
Swap the interstitial vanadium for niobium and that problem disappears.