Knock Your 3D Printer Down To 2D

Hackers love 3D printers. In fact, they might love them a little too much. We hope know we aren’t be the only ones who couldn’t turn down a good deal on an overseas printer (or two). But when you’re not pumping out plastic boats and other PLA dust collectors, what are you supposed to do with them?

Well if you’re like [Uri Shaked] you could hand them a pen and tell them to get writing. The holidays are coming up quick, and somebody’s gotta sign all these cards. In his detailed write-up, he shows how he was able to add a pen to his Creality CR-10 printer to turn it into a lean mean letter-writing machine without making any permanent changes to the printer.

The physical aspect of this hack is about as simple as they come: just come up with some way to hold the pen a bit below the printer’s hotend. The positioning here is a bit critical, as you don’t want to crash the nozzle into the bed while writing out a missive. [Uri] got fancy and designed a little bracket that clamps onto the CR-10 and even has a M3 screw to hold the pen in place, but you could get away with zip ties if you just want to experiment a bit.

[Uri] goes into much greater detail on the software side of things, which is good, as it does take a bit of Inkscape trickery to get the printer to perform the specific dance moves required. He goes through step by step (with screen shots) explaining how to set up Orientation Points and configure the tool parameters for optimal performance. Even if you aren’t looking to put a 3D printer to work autographing your 8x10s before the next hackerspace meet, this is an excellent guide on producing GCode with Inkscape which can be helpful for tasks such as making PCBs.

The general process here is very similar to adding a laser module to your 3D printer, but with considerably lower risk of your eyeballs doing their best Death Star impression.

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Keep ‘Em Flying with this Monster DIY Battery

If you’ve spent an afternoon at the sticks of a remote-controlled aircraft, you’re probably well aware of the great limiter for such exploits: battery life. In the days when most RC aircraft were gas powered it was easy to cart along some extra fuel to keep the good times rolling, but now that everything except big scale models are using electric motors, RC pilots are looking for better ways to charge their batteries in the field.

Though it might seem counter-intuitive, [Adam Pyschny] is of the opinion that the best way to keep his quadcopter batteries charged is to simply use another, much bigger, battery. Rather than mess around with inverters or generators, he can simply use a DC-to-DC battery charger and his huge custom-built battery pack to keep flying.

The pack contains 36 Samsung INR18650-35E 3500mAh cells, which gives it a total capacity of 454Wh. At 1965 grams (4.3 lbs) the pack isn’t exactly a featherweight, but it’s significantly lighter than carting a small generator or even a lead-acid battery to the field.

[Adam] designed a slick case in FreeCAD and printed it in Minadax ASA-X filament, which is specifically designed for outdoor use. A particularly nice detail in the case is that the balance connector (used to charge the cells) is cleanly integrated into the side of the pack, rather than just flapping around in the breeze; which annoyingly seems the norm even on commercially produced batteries.

An interesting next step for this project would be the addition of a solar panel and charge controller to help recover in-between charges. Beyond an automated platform to swap the batteries for you, a DIY pack like this might be the easiest way to maximize the amount of time your RC aircraft are in the air where they belong.

The Redox Keyboard

Alternative keyboard layouts like Colemak and Dvorak are nothing new; they allow easier access to more often used keys to reduce the strain placed on the hands during typing. Building on the popularity of the ergonomic Ergodox keyboard, [Mattia Dal Ben] has developed the Redox keyboard, the Reduced Ergodox, to make an even smaller, more ergonomic keyboard.

Like the Ergodox, the Redox uses a columnar layout, where the keys are laid out in columns, each column offset based on the corresponding finger. Where the Redox breaks away from the design of the Ergodox is the thumb keys. [Mattia] started having pain in his pinkies, so he wanted the thumb layouts to take away some of the extra work from the pinkies. The thumb cluster is smaller than its ancestor and includes an additional rotated thumb key.

The Redox has some great improvements over the Ergodox in order to help with the types of strain injuries most associated with typing, hopefully leading to a much nicer interaction with the peripheral that gets the most use.

The mechanical keyboard community is constantly coming up with great new designs and different DIY keyboards and we’ve featured many of them on the site. After you’ve checked out the pictures and schematics [Mattia] has created, take a look at this 3D printed mechanical keyboard, and details of a keyboard design and build were presented at the Hackaday Superconference in 2017.

Adding Analog Touch To (Nearly) Any Mechanical Keyboard

The new hotness for DIY electronics is mechanical keyboards, and over the past few years we’ve seen some amazing innovations. This one is something different. It adds an analog sensor to nearly any mechanical key switch, does it with a minimal number of parts, and doesn’t require any modification of the switch itself. It’s a reddit thread and imgur post, but the idea is just so good we can overlook the documentation on this one.

The key development behind this type of sensor is realizing that nearly every mechanical keyswitch (Cherry MX, Kalth, Gateron) has a spring in the bottom. A spring is just a coil of wire, and an inductor is just a coil of wire, too. By putting a spiral trace on the PCB of a mechanical keyboard underneath the keyswitch, you can sense the inductance of this spring. This does require a little bit of additional hardware, in this case an LDC1614 inductance to digital converter, but this is an I2C-readable part that can, theoretically, be integrated rather easily with any mechanical keyboard PCB and firmware.

The downside to using the LDC1614 is that sampling is somewhat time-limited, with four channels or individual keys being polled at 500 Hz. This isn’t a problem if the use-case is adding analog to your WASD keys, but it may become a problem for an entire keyboard. Additionally, the LDC1614 is a slightly expensive part, at about $2 USD in quantity 1000. A fully analog keyboard using this technique is going to be pricey.

Right now, the proof-of-concept for this analog mechanical keyswitch is just a 0.1 mm flexible PCB that is shoehorned inbetween a Cherry MX red and a (normal) mechanical keyboard PCB. The next step in the development will be a 2×4 keypad with analog sensors, and opening up the hardware and firmware examples up under a GPL license.

DIY Puff-Suck Interface Aims for Faster Text Input

Puff and Suck (or Sip and Puff) systems allow people with little to no arm mobility to more easily interact with computers by using a straw-like unit as an input device. [Ana] tells us that the usual way these devices are used to input text involves a screen-based keyboard; a cursor is moved to a letter using some method (joystick, mouse emulator, buttons, or eye tracking) and that letter is selected with a sip or puff into a tube.

[Ana] saw such systems as effective and intuitive to use, but also limited in speed because there’s only so fast that one can select letters one at a time. That led to trying a new method; one that requires a bit more work on the user’s part, but the reward is faster text entry. The Puff-Suck Interface for Fast Text Input turns a hollow plastic disk and a rubber diaphragm into bipolar pressure switch, able to detect three states: suck, puff, and idle. The unit works by having an IR emitter and receiver pair on each side of a diaphragm (one half of which is shown in the image above). When air is blown into or sucked out of the unit, the diaphragm moves and physically blocks one or the other emitter-receiver pair. The resulting signals are interpreted by an attached Arduino.

How does this enable faster text input? By throwing out the usual “screen keyboard” interface and using Morse code, with puffs as dots and sucks as dashes. The project then acts as a kind of Morse code keyboard. It does require skill on the user’s part, but the reward is much faster text entry. The idea got selected as a finalist in the Human-Computer Interface Challenge portion of the 2018 Hackaday Prize!

Morse code may seem like a strange throwback to some, but not only does the bipolar nature of [Ana]’s puff-suck switch closely resemble that of Morse code input paddles, it’s also easy to learn. Morse code is far from dead; we have pages of projects and news showing its involvement in everything from whimsical projects to solving serious communication needs.

Send Smooches over Skype with the Kiss Interface

This project of [Nathan]’s certainly has a playful straightforwardness about it. His Skype ‘Kiss’ Interface has a simple job: to try to create a more intuitive way to express affection within the limits of using Skype. It all came about from a long distance relationship for which the chat program was the main means of communicating. Seeking a more intuitive and personal means of expressing some basic affection, [Nathan] created a capacitive touch sensor that, when touched with the lips, sends the key combination for either a kissy face emoji or the red lips emoji, depending on the duration.

Capacitive touch sensing allows for triggering the sensor without actually physically touching one’s lips to the electrodes, which [Nathan] did by putting a clear plastic layer over the PCB traces. His board uses an STM32 microcontroller with software handling the USB HID and STM’s TSC (Touch Sensing Controller) functionality. As a result, the board has few components and a simple interface, which was in keeping with the goal of rejecting feature creep and focusing on a simple task.

Clearly the unit works; but how well does it actually fulfill its intended purpose? We don’t know that yet, but we do know that [Nathan] seems to have everything he needs in order to find out. Either way, it’s a fun project that definitely fits the spirit of the Human-Computer Interface Challenge of The Hackaday Prize.

Make An Electric Skateboard For Your Cat

Have you ever looked at your cat and thought “You know, my kitten really needs an electric skateboard!” Probably not, but this seems to have happened to [Kim Pimmel] while looking at his cat MIDI, so he decided to build one. This process involved building a simple, low powered skateboard with a Feather mainboard and motor controller combined with a laser-cut switch mechanism. When [Kim] puts a treat into the mechanism, the cat pulls the switch and the skateboard moves forward, moving into a brave new e-skateboarding feline future. MIDI looks somewhat unimpressed by this whole business, but I suspect that as long as the treats keep coming, he will be happy to keep on truckin’. Now, if he can just figure out how to persuade the cat to ollie, we will be really getting somewhere.

Feline tomfoolery seems to be a regular pastime here on these pages, and more than just a quest for easy moggy-driven clickbait. A lot of cat feeders and cat finders abound, but this project isn’t the only cat-operated one. Our readers’ pets can probably spot an Arduino a mile away by now.

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