Walnut Windfall Winds Up In Custom Keyboard

June 21, 2016 by Dan Maloney 7 Comments

When a neighbor decided to cut down a walnut tree, [voluhar] decided to make something of the wood. The result was this custom keyboard that combines wood and metal in a lovely and functional package.

Walnut is a wood with a rich heritage in consumer electronics. Back in the early days of TV, huge console sets were built into solid walnut cabinets and proudly displayed along with the other fine furnishings in a home. [voluhar]’s keyboard captures a little of that spirit while retaining all the functionality you’d expect. From the custom PCB to the engraved aluminum key caps, it looks like every part was machined with a CNC router. The keyboard sports satisfyingly clicky Cherry MX switches, and a few cleverly positioned LEDs provide subtle feedback on the state of the locking keys. As for the imperfections in the walnut case, we think it just adds to the charm and warmth of the finished product, which would look great on any desktop.

Wood has appeared in a couple of custom keyboards that we’ve featured before, like this all-wood version. But if you want the retro look without the wood, you could always try a keyboard built out of a typewriter.

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Brutal Water Cannon Defeats Summer Heat; Kills It On Documentation

June 21, 2016 by Dan Maloney 21 Comments

There’s a war on, and while this over-the-top water blaster is certainly an escalation in the Water Wars arms race, that’s not the war we’re referring to. We’re talking about the Documentation War. Hackers, you’re on notice.

If you want to see how a project should be documented, look no further than [Tim]’s forum posts over at WaterWar.net. From the insanely detailed BOM with catalog numbers and links to supplier websites, to scads of build photos with part number callouts, to the finely detailed build instructions, [Tim] has raised the stakes for anyone that documents any kind of build.

And that’s not even touching on the merits of the blaster itself, which has air and water tanks plumbed with every conceivable valve and fitting. There’s even an inline stream straightener made of bundled soda straws to keep the flow as laminar as possible. It looks like [Tim] and his colleagues are obsessed with launching streams of water as far as possible, and although bad weather has prevented an official measurement so far, from the video below it sure looks like he’s covering a huge distance with a stream that stays mostly intact to deliver the full blast to its intended target without losing a drop.

For as much fun as amped-up water guns appear to be, we haven’t seen too many grace these pages before. Going way back we covered a DIY super-soaker. For something much less involved than [Tim’s] masterpiece, you can pull together this pressurized water pistol in an afternoon.

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Micro Tesla Turbine Is An Engineering Tour De Force

June 17, 2016 by Dan Maloney 64 Comments

A corollary to Godwin’s Law ought to be that any Hackaday post that mentions Nikola Tesla will have a long and colorful comment thread. We hope this one does too, but with any luck it’ll concentrate on the engineering behind this tiny custom-built Telsa turbine.

For those not familiar with Mr. Tesla’s favorite invention, the turbine is a super-efficient design that has no blades, relying instead on smooth, closely spaced discs that get dragged along by the friction of a moving fluid. [johnnyq90]’s micro version of the turbine is a very accomplished feat of machining. Although at first the build appears a bit janky, as it progresses we see some real craftsmanship – if you ever doubt that soda can aluminum can be turned, watch the video below. The precision 25mm rotor goes into a CNC machined aluminum housing; the way the turned cover snaps onto the housing is oddly satisfying. It looks like the only off-the-shelf parts are the rotor bearings; everything else is scratch-made. The second video ends with a test spool-up that sounds pretty good. We can’t wait for part 3 to find out how fast this turbine can turn.

Size matters, and in this case, small is pretty darn impressive. For a larger treatment of a Tesla turbine, see this one made of old hard drive platters.

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Wheel Of Resistors Form Unique Rotary Encoder

June 15, 2016 by Dan Maloney 75 Comments

Continuing his tradition of making bits of wire and scraps of wood work wonders, [HomoFaciens] is back with a unique and clever design for an electromechanical encoder.

There are lots of ways to build an encoder, and this is one we haven’t seen before. Not intended in any way to be a practical engineered solution, [HomoFaciens]’ build log and the video below document his approach. Using a rotating disc divided into segments by three, six or eight resistors, the encoder works by adding each resistor into a voltage divider as the disc is turned. An Arduino reads the output of the voltage divider and determines the direction of rotation by comparing the sequence of voltages. More resistors mean higher resolution but decreased maximum shaft speed due to the software debouncing of the wiped contacts. [HomoFaciens] has covered ground like this before with his tutorial on optical encoders, but this is a new twist – sort of a low-resolution continuous-rotation potentiometer. It’s a simple concept, a good review of voltage dividers, and a unique way to sense shaft rotation.

Is this all really basic stuff? Yep. Is it practical in any way? Probably not, although we’ll lay odds that these encoders find their way into a future [HomoFaciens] CNC build. Is it a well-executed, neat idea? Oh yeah.

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Barb Makes Mechanical Pokey Finger With Filament Rivets

June 11, 2016 by Elliot Williams 11 Comments

We were trolling around Hackaday.io, and we stumbled on [Barb]’s video series called (naturally enough) “Barb Makes Things“. The plot of her videos is simple — Barb points a time-lapse camera at her desk and makes stuff. Neat stuff.

Two particularly neat projects caught our attention: a mechanical pointy-finger thing and the useful 3D-printing-filament rivets that she used to make it. (Both of which are embedded below.) The finger is neat because the scissor-like extension mechanism is straight out of Wile E. Coyote’s lab.

But the real winners are the rivets that hold it together. [Barb] takes a strand of filament, and using something hot like the side of a hot-glue gun, melts and squashes the end into a mushroom rivet-head. Run the filament through your pieces, mushroom the other end, and you’re set. It’s so obvious after seeing the video that we just had to share. (Indeed, a lot of cheap plastic toys are assembled using this technique.) It’s quick, removable, and seems to make a very low-friction pivot, which is something that printed pins-into-holes tends not to. Great idea!

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Zero Parts-Count Temperature Sensor

June 10, 2016 by Elliot Williams 24 Comments

Quick: What’s the forward voltage drop on a conducting diode? If you answered something like 0.6 to 0.7 V, you get a passing grade, but you’re going to have to read on. If you answered $V_F = \frac{T-T_0}{k}$ where T₀ and k are device-specific constants to be determined experimentally, you get a gold Jolly Wrencher.

[Jakub] earned his Wrencher, and then some. Because not only did he use the above equation to make a temperature sensor, he did so with a diode that you might have even forgotten that you have on hand — the one inside the silicon of a MOSFET — the intrinsic body diode.

[Jakub]’s main project is an Arduino-controlled electronic load that he calls the MightWatt, and a beefy power MOSFET is used as the variable resistance element. When it’s pulling 20 or 30 A, it gets hot. How hot exactly is hard to measure without a temperature sensor, and the best possible temperature sensor would be one that was built into the MOSFET’s die itself.

There’s a bunch of detail in his write-up about how he switches the load in and out to measure the forward drop, and how he calibrates the whole thing. It’s technical, but give it a read, it’s good stuff. This is a great trick to have up your sleeve.

And if you’re in the mood for more stupid diode tricks, we recommend using them as solar cells or just stringing a bunch of them together to make a thermal camera.

Doc Johnson’s Shape Memory Motor

June 9, 2016 by Al Williams 52 Comments

Nitinol is a kind of wire that has a memory. If you heat it, it tries to return to the shape it remembers. [Latheman666] recently posted a video (see below) of a Nitinol engine that uses a temperature differential to generate motion.

[Dr. Alfred Johnson] holds a patent on this kind of motor. The concept sounds simple enough. A Nitnol spring shrinks in hot water and expands in cold. The spring is looped over two pulleys. One pulley is geared so it has mechanical advantage over the other one so that there’s a net torque which moves the hot part of the spring towards the cold side, and feeds more cold spring into the hot water. The cold spring then contracts and the entire process starts again.

We haven’t entirely gotten our heads around the gearing, but it seems plausible. On the other hand, this video was posted on April 1. What say you, Hackaday Commenteers?

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