Mini Arc Furnace Melts Its Way Into Our Hearts

June 16, 2015 by 44 Comments

[Grant Thompson], aka “The King of Random,” threw caution to the wind when it came to his latest awesome project – a mini electric arc furnace (EAF) (YouTube link). [Grant] uses a refractory brick as a furnace and crucible for the molten metal.  He wears eye protection and a respiratory mask as he cuts up the brick – a good idea, since you don’t want to inhale any of that dust. The electrode grips are made with things you can find at a hardware store, including copper wire and coupling, and 2 pairs of vice-grip style pliers. The copper wire is stripped and attached to the metal handle of the pliers using hose clamps. The pliers are now functional electrode grips- just put a carbon rod in each grip and hold them close to each other…but not without protection! [Grant] harvested the carbon rods  from the cells of 6V lantern batteries – dead batteries work just as well for this. It’s also a better bet to do this outdoors with decent ventilation and away from anything flammable. [Grant] realized that the rods from the batteries have a wax-like coating on them that takes about 30 seconds to burn off in spectacular flames the first time they make electrical contact. However, you can purchase carbon rods by themselves if you want to avoid ripping open batteries and possibly setting yourself on fire. The mini EAF runs on a welding power supply [Grant] made from microwave oven transformers  (YouTube link).

When it’s time to melt some metal, the scrap metal is placed into a bowl drilled into the brick. Using the electrode grips, the carbon rods are placed into the brick’s pre-drilled holes. It only takes ten seconds to melt pure zinc – do NOT do this with galvanized steel or brass castings, as zinc oxide is very hazardous to your health.

In the videos featured below, [Grant] shows a variety of metals are no match for his mini EAF. He even manages to melt rocks from his backyard! It goes without saying that an EAF (video link) can be very dangerous. When you’re dealing with high voltage, plasma, white-hot molten metal, and toxic fumes, you better know what you’re doing (or have a great life insurance policy). [Grant] has a penchant for showcasing projects that can make an OSHA inspector cringe,  but you have to admire his gumption!

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A Game Pad For The Apple II

June 16, 2015 by 10 Comments

[Quinn Dunki] has been hard at work building a Teddy Top – an Apple IIc Plus modified for a road warrior. It has a 3.5 inch disk drive, runs at a blistering four megahertz, and has a beautiful integrated color LCD. It would be a shame to have such a great machine and no way to play games as they were intended, so [Quinn] set about building a game pad for her lovable Apple II.

The Apple II joystick port isn’t as simple as an Atari or Commodore joystick port. Where the bog-standard Atari joystick is basically just a bunch of switches connected to pins, the Apple II joystick is analog. Weird, and even weirder is the value of the pots in these joysticks: 150kΩ. Somehow or another, nobody makes pots in this value any more. Luckily the hardware in these joysticks is well documented, and shoehorning in modern components isn’t that bad.

The Apple joystick has a bit of circuitry – a 556 timer chip that reads the values of each pot and converts that into a stream of 0s and 1s for the Apple. The joystick [Quinn] found for her game pad is an analog thumb stick on a neat breakout board manufactured by Parallax. This analog joystick has 10kΩ pots in it, and that just won’t work with the 556 timer chip. However, since this is just resistors and a 556 chip, adjusting some of the values on the original schematics does the trick. [Quinn] added a few capacitors to her circuit, and everything worked beautifully.

With the electronics down, she turned her attention to the case for her Apple II road warrior enclosure. She recently picked up a 3D printer, which means she’s new to 3D printing. After spending a few hours designing a controller in 123D Design, she sent the files over to the printer. Warping happened. She tried an ABS slurry. The part was stuck to the bed. It took a few tries (purple glue sticks are awesome, [Quinn]), but she eventually got her plastic enclosure printed out, and the circuitry installed. The result is a portable computer, with a custom controller, playing Lode Runner. Can’t beat that.

Retrotechtacular: Making Porcelain Insulators

June 16, 2015 by 12 Comments

Here is a silent film produced by General Electric that depicts the making of many kinds of porcelain insulators for power lines. Skilled craftsmen molded, shaped, and carved these vital components of the electrical grid by hand before glazing and firing them.

Porcelain insulators of this time period were made from china clay, ball clay, flint, and feldspar. In the dry process, ingredients are pulverized and screened to a fine powder and then pressed into molds, often with Play-Doh Fun Factory-type effects. Once molded, they are trimmed by hand to remove fins and flashing. The pieces are then spray-glazed while spinning on a vertical lathe.

Other types of insulators are produced through the wet process. The clay is mixed in a pug mill, which is a forgiving machine that takes scrap material of all shapes, sizes, and moisture levels and squeezes out wet, workable material in a big log. Chunks of log are formed on a pottery wheel or pressed into a mold. Once they are nearly dry, the pieces get their final shape at the hands of a master. They are then glazed and fired in a giant, high-temperature kiln.

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Phonographs Through The Eye Of An Electron Microscope

June 16, 2015 by 32 Comments

Hackaday Prize judge [Ben Krasnow] has been busy lately. He’s put his scanning electron microscope (SEM) to work creating an animation of a phonograph needle playing a record. (YouTube link) This is the same 80’s SEM [Ben] hacked back in November. Unfortunately, [Ben’s]  JSM-T200 isn’t quite large enough to hold an entire 12″ LP, so he had to cut a small section of a record out. The vinyl mods weren’t done there though. SEMs need a conductive surface for imagingphono_anim_1. Vinyl is an insulator. [Ben] dealt with this by using his vacuum chamber to evaporate a thin layer of silver on the vinyl.

Just imaging the record wouldn’t be enough; [Ben] wanted an animation of a needle traveling through the record grove. He tore apart an old phonograph needle and installed it in on a copper wire in the SEM. Thanks to the dual stage setup of the JSM-T200, [Ben] was able to move the record-chip and needle independently. He could then move the record underneath the needle as if it were actually playing. [Ben] used his oscilloscope to record 60 frames, each spaced 50 microns apart. He used octave to process the data, and wound up with the awesome GIF animation you see on the left. 

pits[Ben] wasn’t done though. He checked out a few other recording formats, including CD and DVD optical media, and capacitance electronic disc, an obscure format from RCA which failed miserably in the market. The toughest challenge [Ben] faced was imaging the CD media. The familiar pits of a CD are stored on a thin aluminum layer sandwiched between the lacquer label and the plastic disc. He tried dissolving the plastic with chemicals, but enough plastic was left behind to distort the image. The solution turned out to be double-sided tape. Sticking some tape down on the CD and peeling it off cleanly removed the aluminum, and provided a sturdy substrate with which to mount the sample in the SEM.

We’re curious if stereo audio data can be extracted from the SEM images.  [Oona] managed to do this with a mono recording from a toy robot.  Who’s going to be the first one to break out the image analysis software and capture some audio from [Ben’s] images?

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Prevent Failed Prints With A Filament Speed Sensor

June 16, 2015 by 41 Comments

If you have used a 3D printer for any length of time, you’ve probably experienced a failed print caused by a clogged nozzle. If you’re not around to stop the print and the nozzle stays hot and full of filament for hours, the clog gets even worse. [Florian] set out to solve this issue with an encoder that measures filament speed, which acts as an early warning system for nozzle clogs.

static1.squarespace.com[Florian] designed a small assembly with a wheel and encoder that measures filament movement. The filament passes under the encoder wheel before it’s fed into the 3D printer. The encoder is hooked up to an Arduino which measures the Gray code pulses as the encoder rotates, and the encoder count is streamed over the serial port to a computer.

When the filament slows down or stops due to a nozzle clog, the Python script plays a notification sound to let you know that you should check your nozzle and that your print might fail. Once [Florian] works out some of the kinks in his setup, it would be awesome if the script could stop the print when the nozzle fails. Have any other ideas on how to detect print failures? Let us know in the comments.

Come To Our Shenzhen Meetup And Tell Your Friends

June 16, 2015 by 4 Comments

This Saturday we’ll be in Shenzhen hosting a meetup at Bionic Brew at 19:00. Join us there and bring along your own hardware projects to show around. Everyone loves hearing about that latest build!

Even if you’re not in the area you can help us out by spreading the word. Tell your friends, share on your social media, and let us know about anyone in town who you think we should reach out to. Here’ s a poster if you want to print it out and hang it at your hackerspace, workplace, or other area where awesome people congregate.

The things you can do at this meetup: Laugh, drink, eat, and be happy. Talk excitedly about datasheets and timing diagrams. Pretend you hate talking about timing diagrams while being secretly giddy that someone wants to hear what you think of them. Recount your epic battles to meet production deadlines. Show off that latest blinky LED project you just got working. Meet a ton of awesome people. You can RSVP here to tell us you’re coming. See you soon!

Get Up, Stand Up. With A Little Help From The Mindfulness Bracelet

June 16, 2015 by 10 Comments

[Becky Stern] has created the mindfulness bracelet, a wearable which looks great and serves an important purpose. The bracelet buzzes every hour to remind you to stand up and take a break from work, soldering, gaming, or whatever it is you may be doing. The bracelet is made up of interlinked figure 8 shapes of leather, though [Becky] says rubber from a bicycle inner tube works great as well. The final shape reminds us of the link belts sometimes found on lathes or other industrial equipment. The links are the perfect size to slip an Arduino Gemma in, along with a battery and vibrating motor. A NPN transistor, diode, and resistor round out the entire bill of materials for this design. This bracelet is a heck of a lot cheaper than the Apple watch feature which inspired it!

The time interval is set in the code to 1 hour, and can be adjusted by the user. Although the times are stored in milliseconds, the design does use the ATtiny85’s Watchdog Timer (WDT) to conserve power. This means the time can drift up to 30 seconds per hour, which is fine in this application.

Click past the break to see the bracelet in action!

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