How anodization is used to make pretty iPod colors

What do those colorful iPod Nano cases have in common with sapphires? In both substances the color is not on the surface, but integrated in the structure of the material. As usually, [Bill Hammack] unveils the interesting concepts behind coloring metal through anodization in his latest Engineer Guy episode.

We’re not strangers to the anodization process. In fact we’ve seen it used at home to change the color of titanium camping utensils. [Bill] explains what is actually going on with the electrochemical process; touching on facts we already knew; like that the voltage range will affect the color of the annodized surface. But he goes on to explain why these surfaces are different colors and then outlines how anodized metals can be dyed. That’s right, those iPod cases are colored with dye that will not wash or scratch off.

Pores are opened when the aluminum goes through anodization. Those pores are filled with dye, then the metal is boiled in water which closes them, sealing in the color. Pretty neat!

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All Aluminum Longboard Shows Its Mettle

Reddit user [davvik] made an album to show off his custom all aluminum longboard.  The whole setup weighs about 12lbs, which is not exactly light for a board.  In spite of the added weight [davvik] comments that it is actually pretty responsive. The design is not uncommon but seems to have opted out of the speed holes in favor of structural rigidity, and frankly we love it.

We might not risk wearing sandals on the thing, but [davvik] says for the most part the whole setup has the feel of a wooden longboard, and the added weight makes it fun downhill.  Future plans for the board include machining out the ends, we think this would be a great opportunity for some DIY anodizing!

[via Reddit]

Carabiner helps you hone your milling skills

[Christian] is learning to use the metal milling tools at what we assume is his local Hackerspace. We love this about the communal spaces, they provide so many opportunities to delve into new fields. He embarked on a voyage that included visits to most of the machinery in the shop as he build his own carabiner with a magnetic gate. He’s not going to be hanging off the side of a mountain from it. But his keys or a water bottle will find a happy home thanks to the device.

It all started with some sketches to establish the shape of the overall design. From there he spent some time modelling the frame of the carabiner in CAD. He’s lucky enough to have access to a water jet which took the SolidWorks files and cut out the aluminum frame for him. That left a part with very sharp edges, so he used a wood router with a carbide bit to round them over.

The next part is adding the gate. He used an end-mill to add a mounting area on the frame. The locking ring for the gate was textured using a knurling tool, and the rest is milled with a simple cutting tool. This gate uses a magnet to center itself, with the knurled ring as the only mechanical latching mechanism. [Christian] does a good job of demonstrating the completed carabiner in the clip after the break.

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Milling ice molds for craft cocktails

Want some fancy ice for your next cocktail party? You can try to find spherical ice-cube trays but you won’t get the kind of results seen here. It turns out the trick to this isn’t how you freeze the water, it’s how you melt the ice.

[Brendan O'Connor] started this project after seeing an ice mold that could make beautiful shapes rather than just cubes. But the price tag was $1400. If he could make his own at a hackerspace we’d bet that would pay his membership for an entire year!

The concept is pretty simple. The video after the break shows the mold he was trying to recreate. It’s two hunks of metal with a shape milled into them. The mold is pre-heated, then an oversized hunk of ice is placed between the blocks. The heat melts away the parts you don’t want, and leaves a perfectly shaped ice orb in between. Gravity is responsible for pulling the mold halves together as they slide along some machined rods.

With a big hunk of scrap aluminum he milled two halves of a sphere. They can be sufficiently heated if held under running water, and a some leftover printer rails keep the two parts aligned as the ice orb is formed. Now [Brendan] just needs to work on his method of creating a crystal-clear ice block as a starter and he’ll have achieved total win.

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Anodizing and dyeing aluminum without battery acid

anodizing_aluminum_without_battery_acid

While many people have tried their hand at anodizing aluminum at home, there are plenty who would just as soon leave it up to the professionals due to the highly concentrated sulfuric acid required for the process. [Ken] started thinking about the process and wondered if there was a way to get comparable results using chemicals that are easier to obtain and dispose of.

Through some experimentation he found that sodium bisulfate (NaHSO4), which is a sodium salt of sulfuric acid, can easily be used in its place with great results. The chemical is typically advertised in hardware and pool stores as “Aqua Chem”, and can be had at a very reasonable price. When paired with the proper DC current along with a cathode, the sodium bisulfate easily anodizes an aluminum workpiece and renders it ready for coloring with RIT, readily available cloth dye.

We were impressed with the results, and when looking at [Ken’s] test pieces, it seems that the metal dyed with sodium bisulfate has a more uniform, less streaky coloring to it. It’s also worth mentioning that [Ken] has found it is fairly easy to etch the aluminum before anodizing using a solution of sodium hydroxide, which is great for individuals who prefer a more matte finish.

If this is something that interests you, be sure to swing by his site. He has a posted nice video overview of the process that may be of some help.

Powering vehicles with aluminum

Pop a few aluminum bits into this little RC racer and you’ll have power for around forty minutes. This concept, which has been patented, is the result of a college research project. It uses a chemical reaction between aqueous Sodium Hydroxide and aluminum. The result of that reaction is hydrogen, which is gathered and directed to a fuel cell that drives the car.

Novel? Yes. Interesting? Absolutely. But you should be raising an eyebrow at the dubious choice of fuel that is aluminum.

If you don’t know what we’re talking about let us paint you a picture. Aluminum is a metal that is refined from bauxite ore. It takes an immense amount of electricity to smelt the metal. This is usually justified because aluminum is one of the most recyclable substances on earth, capable of being melted down and reformed countless times. But dissolving it in drain cleaner breaks it down and then it’s gone. So what we have here simply must be the least efficient disposable battery so far developed. It’d probably use less resources to grow and harvest lemons as a power source.

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Making boxes from soda cans

This shiny little box was made from a soda can. You don’t need much to pull this off; an aluminum can, sand paper, scissors, a ballpoint pen, a straight edge, and some time. The embossing is done with the tip of the pen, but there’s a bit of a trick to it. The designs are first pressed into the metal from the underside of the aluminum. It is then flipped over and the outlines are traced, with one last tracing of the shape from the underside once that is completed. We think you’ll agree that this results in an impressive relief of the design.

This would make a nice project for that wedding ring you’ve been carrying around sans-case. Or perhaps this is just what you needed as an enclosure for your next project. You’ll find an instructional video after the break.

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