Polymer Discovery Gives 3D-printed Sand Super Strength

Research activity into 3D printing never seems to end, with an almost constant stream of new techniques and improvements upon old ones hitting the news practically daily. This time, the focus is on a technique we’ve not covered so much, namely binder jetting additive manufacturing (BJAM for short, catchy huh?) Specifically the team from Oak Ridge National Laboratory, who have been exploring the use of so-called hyperbranched Polyethyleneimine (PEI) as a binder for jetting onto plain old foundry silica sand (nature, free access.)

Roll, spray, bake. Simples.

The PEI binder was mixed with a 75:25 mix of water and 1-propanol (not to be mixed up with 2-propanol aka isopropanol) to get the correct viscosity for jetting with a piezoelectric print head and the correct surface tension to allow adequate powder bed penetration, giving optimal binding efficiency. The team reported a two-fold increase in strength over previous jetting techniques, however, the real news is what they did next; by infusing the printed part (known as the green part) with common old ethyl cyanoacrylate (ECA, or super glue to us) the structural strength of the print increased a further eight times due to the reaction between the binder and the ECA infiltrate.

To further bestow the virtues of the PEI binder/ECA mix, it turns out to be water-soluble, at least for a couple of days, so can be used to make complex form washout tooling — internal supports that can be washed away. After a few days, the curing process is complete, resulting in a structure that is reportedly stronger than concrete.  Reinforce this with carbon fiber, and boy do you have a tough building material!

Not bad for some pretty common materials and a simple printing process.

We covered a similar binder jetting process for using sawdust a little while ago, and a neat way of printing with metal powder by carrying it in a stream of argon and cooking it with a laser, but there is an opening for a DIY effort to get in on the binder jetting game.

Thanks [Victor] for the tip!

A Trackball So Good You Can’t Buy It

The projects we feature on Hackaday are built to all standards, and we’d have to admit that things have left our own benches as bundles of wire and tape. Sometimes we see projects built to such a high standard that we’re shocked that they aren’t a high-end manufactured product, such as [jfedor2]’s two-ball trackball project. It combines a pair of billiard balls and a couple of buttons with a beautifully-designed 3D-printed case that looks for all the world as though it came from a premium peripheral brand.

Inside are a pair of PMW3360 optical sensors on PCBs mounted with a view into the billiard ball sockets, and for which the brains come courtesy of an RP2040 microcontroller. There are five PCBs in all, each having a set of purpose-built stand-offs to hold it. The result appears to be about as good a trackball as you’d hope to buy, except of course that you can’t. All the files to make your own are in the GitHub repository though, so all is not lost.

Over the years we’ve brought you a variety of trackball designs, including at least one other build using a billiard ball.

Light-Tracking BEAM Robot Can See The Light

BEAM robotics, which stands for Biology, Electronics, Aesthetics, and Mechanics, is an ethos that focuses on building robots with simple analog circuits. [NanoRobotGeek] built a great example of the form, creating a light-tracking robot that uses no batteries and no microcontrollers.

The robot aims to track the brightest source of light it can see. This is achieved by feeding signals from four photodiodes into some analog logic, which then spits out voltages to the two motors that aim the robot, guiding it towards the light. There’s also a sound-detection circuit, which prompts the robot to wiggle when it detects a whistle via an attached microphone.

The entire circuitry is free-formed using brass wire, and the result is an incredibly artful build. Displayed in a bell jar, the build looks like some delicate artifact blending the past and future. Neither steampunk nor cyberpunk, it draws from both with its combination of vintage brass and modern LEDs.

It’s a great build that reminds us of some of the great circuit sculptures we’ve seen lately. Video after the break.

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Pete's Simple Seven SSB Transceiver

PSSST! Here’s A Novel SSB Radio Design With Only Seven Transistors

When [Pete Juliano] sat down to design a sideband transceiver for the 20 Meter (14 MHz) ham radio band, he eschewed the popular circuits that make up so many designs. He forged ahead, building a novel design that he calls Pete’s Simple Seven SSB Transceiver, or PSSST for short.

What makes the PSSST so simple is not only its construction, but the low component count. The same circuit using four 2N2222A’s is used on both transmit and receive. On transmit, an extra three components step in to amplify the microphone input and build output power, which is 2.5-4 Watts, depending on the final output transistor used. The best part is that all of the transistors can be had for under $10 USD! [Pete] shows where radio components such as the RF mixers and the crystal filter can be purchased, saving a new constructor a lot of headaches. The VFO and IF frequencies are both provided by the venerable si5351a with an Arduino at the helm.

Many simple transceivers are designed to demonstrate a minimum viable radio, with performance not really a goal. On the other hand, the PSSST was modeled stage-by-stage in LTSpice, ensuring great transmit audio and nice receiver performance. Be sure to check out the demonstration below the break!

[Pete] has painstakingly documented the entire project on his website, and the code for the VFO is available by request via email. We appreciate this contribution to the homebrew ham radio community, and we’re sure this will provide many nights of solder smoking enjoyment for radio amateurs around the world.

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FlowIO Takes Top Honors In The 2021 Hackaday Prize

FlowIO Platform, a modular pneumatics controller for soft robotics and smart material projects, took home Grand Prize honors at the 2021 Hackaday Prize. Aside from the prestige of coming out on top of hundreds of projects and bragging rights for winning the biggest hardware design challenge on Earth, the prize carries an award of $25,000 and a Supplyframe DesignLab residency to continue project development. Four other top winners were also announced at the Hackaday Remoticon virtual conference on Saturday evening.

In a year full of challenges, this year’s Hackaday Prize laid down yet another gauntlet: to “Rethink, Refresh, and Rebuild.” We asked everyone to take a good hard look at the systems and processes that make the world work — or in some cases, not work — and reimagine them from a fresh perspective. Are there better ways to do things? What would you come up with if you started from a blank piece of paper? How can you support and engage the next generation of engineers, and inspire them to take up the torch? And what would you come up with if you just let your imagination run wild?

And boy, did you deliver! With almost 500 entries, this year’s judges had quite a task in front of them. Each of the five challenges — Refresh Displays, Rethink Work-From-Home Life, Reimagine Supportive Tech, Redefine Robots, and Reactivate Wildcard — had ten finalists, which formed the pool of entries for the overall prize. And here’s what they came up with.

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Cheating A Pedometer The Easy Way

These days, pedometers are integrated into just about every smartwatch on the market, and some of the dumber ones too. Tracking step counts has become a global pastime, and at times, a competitive one. However, any such competition can easily be gamed, as demonstrated by [Luc Volders].

Generally, all it takes to fool a basic pedometer is a gentle rhythmic jiggling motion of some sort. Cheaper devices will even register steps with little more than vague shaking.

[Luc] exploited this with basic machinery. A servo’s output shaft is fitted with a 3D printed cylinder, sized to allow a smartwatch to be attached as if to a wrist. Then, a Raspberry Pi Pico simply rocks the servo back and forth at regular intervals, and the watch begins counting these ersatz steps. Looking at the project as a whole, we’re betting [Luc] took some inspiration from old-fashioned automatic watch winders.

It’s hard to envision an important application for this technology. However, if one is in a friendly competition with friends who don’t scrutinize the results too closely, this would be an easy way to win.

Alternatively, consider building a pedometer to track your hamster’s exercise regime. If you’ve got your own exercise hacks on the go, drop us a line!

The (Sodium Chloride) Crystal Method

[Chase’s] post titled “How to Grow Sodium Chloride Crystals at Home” might as well be called “Everything You Always Wanted to Know about Salt Crystals (but Were Afraid to Ask).” We aren’t sure what the purpose of having transparent NaCl crystals are, but we have to admit, they look awfully cool.

Sodium chloride, of course, is just ordinary table salt. If the post were simply about growing random ugly crystals, we’d probably have passed over it. But these crystals — some of them pretty large — look like artisan pieces of glasswork. [Chase] reports that growing crystals looks easy, but growing attractive crystals can be hard because of temperature, dust, and other factors.

You probably have most of what you need. Table salt that doesn’t include iodine, a post, a spoon, a funnel, filter paper, and some containers. You’ll probably want tweezers, too. The cooling rate seems to be very important. There are pictures of what perfect seed crystals look like and what happens when the crystals form too fast. Quite a difference! Once you find a perfectly square and transparent seed crystal, you can use it to make bigger ones.

After the initial instructions, there is roughly half the post devoted to topics like the effect growth rate has on the crystal along with many pictures. There are also notes on how to form the crystals into interesting shapes like stars and pyramids. You can also see what happens if you use iodized salt.

If salt is too tame for you, try tin. Or opt for copper, if you prefer that.