Maslow Brings The Wall Plotter Into The Woodshop

October 14, 2016 by 55 Comments

Hanging plotters, or two steppers controlling a dangling Sharpie marker on an XY plane, are nothing new to our community. But have you ever thought of trading out the Sharpie for a wood router bit and cutting through reasonably thick plywood sheets? That would give you a CNC machine capable of cutting out wood in essentially whatever dimensions you’d like, at reasonably low-cost. And that’s the idea behind [Bar]’s Maslow. It’s going to be a commercial product (we hope!), but it’s also entirely open source and indubitably DIYable.

[Bar] walks us through all of the design decisions in this video, which is a must-watch if you’re planning on building one of these yourself. Basically, [Bar] starts out like any of us would: waaaay over-engineering the thing. He starts out with a counterweight consisting of many bricks, heavy-duty roller chain, and the requisite ultra-beefy motors to haul that all around. At some point, he realized that there was actually very little sideways force placed on a sharp router bit turning very quickly. This freed up a lot of the design.

His current design only uses two bricks for counterweights, uses lighter chains, and seems to get the job done. There’s a bit of wobble in the pendulum, which he admits that he’s adjusted for in software. Motors with built-in encoders and gearing take care of positioning accurately. We haven’t dug deeply enough to see if there’s a mechanism to control the router’s plunge, which would be great to cut non-continuous lines, but first things first.

Taking the wall plotter into the woodshop is a brilliant idea, but we’re sure that there’s 99% perspiration in this design too. Thanks [Bar] for making it open! Best of luck with the Kickstarter. And thanks to [Darren] for the tip.

Running LISP On An ESP8266

October 14, 2016 by 23 Comments

LISP is a polarizing language. Either you love it or you hate it. But we’ll put aside our personal preferences to bring you a good hack. In this case a LISP environment running on an ESP8266. [Dmitry] is on the “love it” side of the fence — he’s been waiting for an excuse to code up a LISP interpreter for a while, and he found one in the ESP8266.

there-is-always-a-way-2Actually, [Dmitry] is running LISP inside JavaScript, which is itself presumably coded up in C, before it’s assembled to run on an ESP8266. (It’s turtles all the way down!) This means that he can piggy-back on JavaScript’s garbage collection and console handling and so on. After picking a suitably small LISP implementation (actually a Scheme dialect for those of you who know the difference), he went to work.

One weekend bled into the next, but he got the system running, connected to the network, and had LEDs blinking! In the end, he even managed to squeeze in some optimization for memory’s sake. Pretty cool, and because it takes advantage of an already complete system, it can even be made pretty useful. Not bad for a few weekends’ work!

And finally, if Lots of Irritating Silly Parentheses is your idea of a good time, but the wealth of computing resources available on an ESP8266 seem overkill, have a look at Microlisp, running on an AVR. Or go to the opposite extreme, and run a LISP OS on a Raspberry Pi. Whatever you do, don’t forget to close your parentheses! (We’re told that’s a traditional LISPer farewell.)

Hackaday Prize Entry: A Cheap, Portable Incubator

October 13, 2016 by 23 Comments

Millions of premature babies are born every year, and more than a few of these births occur hours away from any hospital with a NICU. [Manoj]’s entry for the Hackaday Prize is a simple, but very useful primitive incubator. Is it as good as the incubators you would find in a world-class hospital? No, but that’s not the point. This is an incubator for the rest of the world, where neonatal care is lacking.

You’re not going to get mechanical respiration or even oxygen into a device that is meant for the most far-flung areas on the planet, so this incubator focuses almost solely on monitoring. Packed inside a premie-sized sleeping bag is enough electronics to measure heart rate, blood oxygen, temperature and respiration. Also, there are a few resistive fabric elements to turn electricity into warmth.

Of course, anything you would find in any hospital or clinic would greatly outclass what this project has to offer. That’s really not the point, though; this incubator is cheap, can be deployed anywhere, and provides enough information to hopefully keep a preterm child alive. That’s good enough for us, and makes for a great entry into the Hackaday Prize.

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Pneumatic Launcher Gets Ham Antennas Hanging High

October 13, 2016 by 39 Comments

Amateur radio is an eclectic hobby, to say the least. RF propagation, electrical engineering, antenna theory – those are the basics for the Ham skillset. But pneumatics? Even that could come in handy for hanging up antennas, which is what this compressed-air cannon is designed to do.

[KA8VIT]’s build will be familiar to any air cannon aficionado. Built from 2″ Schedule 40 PVC, the reservoir is connected to the short barrel by a quarter-turn ball valve. Charging is accomplished through a Schrader valve with a cheap little tire inflator, and the projectile is a tennis ball weighted with a handful of pennies stuffed through a slit. Lofting an antenna with this rig is as simple as attaching a fishing line to the ball and using that to pull successively larger lines until you can pull the antenna itself. [KA8VIT] could only muster about 55 PSI and a 70′ throw for the first attempt shown below, but a later attempt with a bigger compressor got him over 100 feet. We’d guess that a bigger ball valve might get even more bang for the buck by dumping as much air as quickly as possible into the chamber.

Looking to launch a tennis ball for non-Ham reasons? We’ve got you covered whether you want to power it with butane or carbon dioxide.

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Keep Tabs On The Weather With Rpi_status

October 13, 2016 by 8 Comments

[Facelessloser] is interested in glanceable information. Glancable devices are things like your car’s dashboard, your wristwatch, or widgets on a smartphone lockscreen. The glanceable information distribution system in this case is rpi_status, [facelessloser’s] entry in the Enlightened Raspberry Pi Contest.

[Facelessloser] coupled a ring of eight WS2812 RGB LEDs with a small OLED screen managed by a the common ssd1306 controller. Since he was rolling his own board for this project, [faceless] some buttons and a BMP180 temperature sensor. Going with popular parts like this meant libraries like the Pimoroni unicorn hat library for the WS2812 were readily available.

A simple display like this can show just about anything – from status of a nightly software build, to traffic along your morning commute. [Facelessloser] is using it for weather data. His data source is Weather Underground’s API. Weather information is displayed on the OLED. The WS2812’s display the temperature. A single blue light means cold. The ring fills as the temperature warms up. After eight degrees of blue, the color changes to orange, followed by red.

Check out the video after the break for a short demo of the board.

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Watch The Diesel Effect In Ballistic Gelatin

October 13, 2016 by 41 Comments

A striking video appears to demonstrate an explosion via the diesel effect in clear ballistic gel. The diesel effect or “dieseling” refers to when a substance ignites from the effects of pressure, and it’s the operating principle behind the gadgets known as Fire Sticks or Fire Pistons.

diesel-effect-ballistics-gelBallistic gel is a broad term referring to a large chunk of dense gel generally used in firearms-related testing to reliably and consistently measure things like bullet deformation, fragmentation, and impact. It’s tough, elastic, and in many ways resembles a gigantic gummi bear. Fans of Mythbusters (or certain DIY railguns) will recognize the stuff. Water-based blocks made with natural gelatin can be easily made at home, but end up with a yellow-brown color and have a limited shelf life due to evaporation. Clear blocks exist that are oil-based and don’t dry out like the water-based ones. It’s one of these that is in the embedded animation below.

Slow motion video capture is a natural companion to just about anything that you’d need ballistic gel for, and good thing — because the video captured what appears to be a diesel effect! The block is hit with a bullet, and as the bullet rapidly expands and dumps its energy into the gel, a cavity expands rapidly. During this process, some of the (oil-based) material in the cavity has been vaporized. After the expanded bullet exits (to the right of the gif above but easier to see in the video below), the cavity in the block begins to collapse. The resulting pressure increase appears to ignite the vaporized material, which explodes with a flash followed by some exhaust.

This effect has been observed in ballistic gel before, but this video shows a particularly clear ignition, followed by a secondary expansion of the cavity, then a flatulent-ish ejection of exhaust as the cavity collapses. If nothing else, it’s a very striking effect clearly captured on film. Slow-motion capture of destructive forces makes visible many things that would otherwise happen too quickly to perceive.

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3D Printed Nozzles Turbocharge Microsphere Production

October 13, 2016 by 14 Comments

Researchers at MIT have used 3D printing to open the door to low-cost, scalable, and consistent generation of microencapsulated particles, at a fraction of the time and cost usually required. Microencapsulation is the process of encasing particles of one material (a core) within another material (a shell) and has applications in pharmaceuticals, self-healing materials, and dye-based solar cells, among others. But the main problem with the process was that it was that it was slow and didn’t scale, and it was therefore expensive and limited to high-value applications only. With some smart design and stereolithography (SLA) 3D printing, that changed. The researchers are not 3D printing these just because they can; they are printing the arrays because it’s the only way they can be made.

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