3D whiteboard without the whiteboard

This one is so simple, and works so well, we’d call it a hoax if April 1st hadn’t already passed us by. But we’re confident that what [William Myers] and [Guo Jie Chin] came up with exists, and we want one of our own. The project is a method of drawing in 3 dimensions using ultrasonic sensors.

They call it 3D Paint, and that’s fitting since the software interface is much like the original MS Paint. It can show you the movements of the stylus in three axes, but it can also assemble an anaglyph — the kind of 3D that uses those red and blue filter glasses — so that the artists can see the 3D rendering as it is being drawn.

The hardware depends on a trio of sensors and a stylus that are all controlled by an ATmega644. That’s it for hardware (to be fair, there are a few trivial amplifier circuits too), making this an incredibly affordable setup. The real work, and the reason the input is so smooth and accurate, comes in the MATLAB code which does the trilateration. If you like to get elbow deep in the math the article linked above has plenty to interest you. If you’re more of a visual learner just skip down after the break for the demo video.

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Making paint with inorganic chemistry

Back during the Renaissance, great artists like Leonardo, Michelangelo, and Raphael would create their own paints. Of course paint is very cheap and readily available, but that doesn’t mean you can’t make your own paint by playing with chemistry.

Last summer, [Sean] at the Philly hackerspace Hive76 did some experiments with ferrofluids. For these experiments [Sean] prepared a bunch of magnetite from rusty iron screws. In the process a lot of iron hydroxide was formed, which can produce wonderful colors. The red-brown eye in the title pic was made from some of the stuff floating on the top of [Sean]’s beaker.

[Sean] was really after something really black, so he turned his efforts towards hematite, a very dark pigment and is now working with other metals to produce some interesting colors. Already he’s made green and yellow pigments with two copper compounds. We’ll just have to hope he uses a fume hood when he starts taking apart mercury switches to make red.

Make your own spray paint cans

[Mikeasaurus] found a way to build his own refillable spraypaint canister. The donor vessel used here is a plastic soda bottle. It’s a great choice since it is engineered to house a pressurized liquid and you can find them for free by intercepting a satisfied soda consumer before they reach the recycling bin.

He repurposed the spray nozzle from a commercial spray paint can. By first releasing all of the pressure from the empty paint he could then use a hack saw to remove the top disk. He used Sugru to attach it to the bottle cap which has a hole drilled in the center to accept the feed straw. We wonder if there wouldn’t be a better way to attach this from the inside of the cap for better resistance to bottle pressure?

The final piece of hardware is a Shrader valve from a bicycle inner tube. This lets you pump up the pressure in the bottle. You’ll need to dilute the paint you use to make it sprayer-friendly. [Mikeasaurus] diluted his six to one which might have been a bit too much judging from the drips seen in the video after the break.

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Color-matching powder coat paints

[Zitt] is sharing some methods he’s honed for color-matching powder coat paint. He developed these techniques while restoring a 1982 Star Trek coin-op machine. The image above shows a paddle used for the game. The plate that houses the control was beat up, and he needed to repaint it but wanted to make sure it didn’t look out-of-place with the molded plastic that surrounds it.

He gets his powder paints from Harbor Freight, a favorite depot for hackable goods (like drill motors, or metal carts). Usually these paints would be applied by attracting them to the piece using electrostatic charges. [Zitt’s] not doing that, but applying them with a paint sprayer instead.

The first step is to match your color. He’s using an electronic color matching device which gives data to plug into a chart on the web for a color match. Once you’ve got a formula, mix up the powder coat, and then dissolve it into some Methyl Ethyl Ketone. This goes into the spray gun and is applied in an even coat. Before heading into an oven for curing, it’s important to wait for this coat to dry. [Zitt] observed some boiling MEK on a wet test piece that left an undesirable texture on the baked paint after curing. After running a few test pieces he picked the blend that was the best match and then painted all of his restored parts.

Hot resistors used for color-changing clock face

[Sprite_TM] built a full clock display using thermochromic paint. This picks up where he left off with his paint-based 7-segment display prototype. He never really saw that design through to a finished project, but he recently came across the leftover paint and decided to do something with it. Instead of making thin traces on a PCB he’s heating up resistors mounted on protoboard. Each resistor has been coated with the black/light grey paint after getting a rough sanding on the tops of the packages. Run around 500mW through a segment and they heat up enough to change the paint to light grey. Once shut off, the segments gradually fade over the next 60 seconds.

Making model rocket motor igniters

[Stephan Jones] has an easy method for making your own model rocket engine igniter. The solid state motors used in this hobby consume one igniter with each electrically triggered launch. Whether you’re making your own motors or not, this construction technique should prohibit you from every buying an igniter again. The process involves bending some nichrome wire around a paper clip, adding some structural support to the leads using masking tape, and insulating the business end with a quick dip in paint.

Now would be a good time to send us your launchpad hacks. All we’ve seen so far is a launchpad for water rockets.

[via Make]

Biopunk watch: time, temperature, gaming

[Matthew Garten] built this watch based on an Arduino. The face is a small color display which allows you to choose to show time in digital, binary, or analog formats. In keeping with the recent trend here on Hackaday he has a glove-based add-on that has temperature sensors in the fingers; for Firefighters or those with nerve damage to their fingers (we’re thinking Darkman). For entertainment in any situation he’s included a trackball and the ability to play breakout or draw in 16-bit color. Details are scarce but apparently he’ll be sharing more soon. For now, watch the video after the break and think of ways to shrink this down into a nice package like the Pong Watch enjoys.

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