LED Matrix Hourglass Knows Which Way Is Up

October 8, 2021 by Donald Papp 6 Comments

[Fearless Night]’s slick dual hourglass doesn’t just simulate sand with LEDs, it also emulates the effects of gravity on those simulated particles and offers a few different mode options.

The unit uses an Arduino (with ATMEGA328P) and an MPU-6050 accelerometer breakout board to sense orientation and movement, and the rest is just a matter of software. Both the Arduino and the MPU-6050 board are readily available and not particularly expensive, and the LED matrix displays are just 8×8 arrays of red/green LEDs, each driven by a HT16K33 LED controller IC.

The enclosure and stand are both 3D-printed, and a PCB not only mounts the components but also serves as a top cover, with the silkscreen layer of the PCB making for some handy labels. It’s a clever way to make the PCB pull double-duty, which is a technique [Fearless Night] also used on their earlier optical theremin design.

Those looking to make one of their own will find all the design files and source code handily available from the project page. It might not be able to tell time in the classical sense, but seeing the hourglass displays react to the device’s orientation is a really neat effect.

Upside-down c-clamp held in a frame, forming a crude press

C-Clamp Becomes Light-Duty Arbor Press

October 7, 2021 by Donald Papp 8 Comments

[ThingaUser] made a tool to solve a specific problem of theirs, but the design also happens to be a pretty good way to turn a c-clamp into a poor man’s light duty arbor press.

The frame is made for a common 4-inch c-clamp.

The problem they had was a frequent need to press nuts and occasionally bearings into other parts. Some kind of press is really the best tool for the job, but rather than buy a press, they opted to make their own solution. By designing and 3D printing an adapter for a common 4-inch c-clamp, a simple kind of light duty press was born.

Sure, one has to turn the handle on the clamp to raise and lower the moveable jaw, and that’s not the fastest operation. But the real value in the design is that the clamp can now stand by itself on a tabletop, leaving the operator to dedicate one hand to manipulating the part to be pressed, while twisting the clamp’s handle with the other hand. There’s no need for a third hand to keep the clamp itself stable in the process. As a bonus, it can print without supports and the clamp secures with zip ties; no other fasteners or glue needed.

Not all c-clamps are the same, so there is a risk that this frame that fits [ThingaUser]’s clamp might not fit someone else’s. In those cases, it’s best to have access to not just the STL file, but also to a version in a portable CAD format like STEP to make it easy to modify. But there are still ways to make changes to an STL that isn’t quite right.

3D Printering: Corrugated Plastic For Cheaper & Easier Enclosures

October 6, 2021 by Donald Papp 37 Comments

Clear acrylic panels have long been a mainstay of 3D printer enclosure designs, but they can also add significant cost in terms of money, shipping, weight, and hassle. An alternative material worth looking at is corrugated plastic (also known by its trade name coroplast) which is cheap, light, an excellent insulator, and easy to work with. Many enclosure designs can be refitted to use it instead of acrylic, so let’s take a closer look at what it has to offer.

What’s Wrong With Acrylic?

It’s not just the purchase price that makes acrylic a spendy option. Acrylic is fairly heavy, and shipping pieces the size of enclosure panels can be expensive. Also, cutting acrylic without special tools can be a challenge because it cracks easily if mishandled. Acrylic cuts beautifully in a laser cutter, but most laser cutters accessible to a hobbyist are not big enough to make enclosure-sized panels. If you are stuck with needing to cut acrylic by hand, here are some tips on how to get by with the tools you have.

It is best to source acrylic from a local shop that can also cut it to size with the right tools for a reasonable price, but it is still far from being a cheap material. There’s another option: corrugated plastic has quite a few properties that make it worth considering, especially for a hobbyist.

Continue reading “3D Printering: Corrugated Plastic For Cheaper & Easier Enclosures” →

Flipper Zero tool reading bank card, displaying data on LCD

What’s On Your Bank Card? Hacker Tool Teaches All About NFC And RFID

October 4, 2021 by Donald Papp 29 Comments

The Flipper Zero is a multipurpose hacker tool that aims to make the world of hardware hacking more accessible with a slick design, wide array of capabilities, and a fantastic looking UI. They are struggling with manufacturing delays like everyone else right now, but there’s a silver lining: the team’s updates are genuinely informative and in-depth. The latest update is all about RFID and NFC, and how the Flipper Zero can interact with a variety of contactless protocols.

Drawing of Flipper Zero and a variety of RFID tags — Popular 125 kHz protocols: EM-Marin, HID Prox II, and Indala

Contactless tags are broadly separated into low-frequency (125 kHz) and high-frequency tags (13.56 MHz), and it’s not really possible to identify which is which just by looking at the outside. Flipper Zero can interface with both, but the update at the link above goes into considerable detail about how these tags are used in the real world, and what they look like from both the outside and inside.

For example, 125 kHz tags have an antenna made from many turns of very fine wire, with no visible space between the loops. High-frequency tags on the other hand will have antennas with fewer loops, and visible space between them. To tell them apart, a bright light is often enough to see the antenna structure through thin plastic.

Low-frequency tags are “dumb” and incapable of encryption or two-way communication, but what about high-frequency (often referred to as NFC) like bank cards and applications like Apple Pay? One thing demonstrated is that mobile payment methods offer up considerably less information on demand than a physical bank or credit card. With a physical contactless card it’s possible to read the full card number, expiry date, and in some cases the name as well as recent transactions. Mobile payment systems (like Apple or Google Pay) don’t do that.

Like many others, we’re looking forward to it becoming available, sadly there is just no getting around component shortages that seem to be affecting everyone.

Flame-Spitting Dragon Head Heats Up Halloween

October 4, 2021 by Donald Papp 4 Comments

Halloween is looming, and [Jonathan Gleich] decided that an ideal centerpiece would be a flame-spitting dragon’s head. It started with an economical wall-mount dragon’s head, combined with a variety of off-the-shelf components to become something greater.

Dragon head with arc ignitor lit — Spark from high-voltage ignitor, right at the torch opening.

The fire comes from a kind of propane torch sold as a weed killer set, which looks a little like a miniature tiger torch. The flow of propane is limited by a regulator (which keeps the flame short and fixed), and controlled with a gas-rated 12 V solenoid valve. Ignition is done with the help of a spark igniter that fires up on demand, fed by a high-voltage ignition coil. The two combine at the Dragon’s mouth, where the flame originates, but the electrical components are otherwise isolated from the gas elements as much as possible.

The dragon head is made of acrylic, and if exposed to enough heat acrylic will first melt, then burn. To help avoid a meltdown, the dragon breathes fire only intermittently. [Jonathan] also gave the mouth area a heat-resistant barrier made from generous layers of flame-blocking mortar and sealants from the hardware store. The finishing touch comes in the form of bright red LEDs in the eyes, which give the head a bit more life.

Watch the ignitor in action and see the head spewing flames in the two short videos embedded below. The head should make for some good pictures come Halloween, and is a good example of how repurposing off-the-shelf items can sometimes be just what is needed for a project.

Interested in something smaller, but still fiery? Check out this pet fire-breathing dragon project for all your robotic animal companion needs. Continue reading “Flame-Spitting Dragon Head Heats Up Halloween” →

3D Printed Rocket’s Features Are Out Of This World

September 22, 2021 by Donald Papp 13 Comments

We’re delighted to see the progress on [Foaly]’s 3D-printed Cortex 2 rocket, and the latest build log is full of beautiful pictures and design details. Not only is this rocket jam-packed with an efficiency of electronics and smart design, but it almost seems out to single-handedly prove that 3D-printing is far from the novelty some think it is.

Electronics and wires packing the fuselage of a model rocket — Cable management and component layout is far from a trivial task in a rocket like this.

There is so much going on in the Cortex 2 that it simply wouldn’t be possible to do everything it does without the ability to make one’s own parts exactly to specification. In fact, there is so much going on that cable management is its own challenge.

Everything in the build log is interesting, but the design of the parachute system is of particular note. [Foaly]’s original Cortex rocket met it’s end when the parachute failed to deploy, and Cortex 2 is determined to avoid that fate if it can. For the parachute and any cords and anchors, a careful layout maximizes the chances of a successful deployment without anything tangling, but there are some extra features as well. The panel covering the parachute is mounted with the help of four magnets, which are mounted with opposing polarities. This provides an initial repulsing force when the door is unlocked by a servo, which should help wind immediately rush in to the opening to blow the panel away. The recovery system even has its own dedicated microcontroller and can operate autonomously; even if software for everything else crashes, the parachute will still get deployed. Locking connectors for all cables also ensure that acceleration forces don’t dislodge any contacts.

Everything about the rocket looks great, and the amount of work that has gone into the software is particularly evident. The main controller even has an interactive pre-flight checklist, which is a fantastic feature.

The last time we saw the Cortex 2 it was still only about half built, and we can’t wait to see how it performs. Rocketry is a field that has benefited greatly from things like 3D printing, the availability of highly-integrated electronics, and even such things as a rocket design workbench for FreeCAD. Better tools enable better work, after all.

Mini Wireless Thermal Printers Get Arduino Library (and MacOS App)

September 21, 2021 by Donald Papp 24 Comments

[Larry Bank]’s Arduino library to print text and graphics on BLE (Bluetooth Low Energy) thermal printers has some excellent features, and makes sending wireless print jobs to a number of common models about as easy as can be. These printers are small, inexpensive, and wireless. That’s a great mix that makes them attractive for projects that would benefit from printing out a hardcopy.

It’s not limited to simple default text, either. Fancier output can be done using Adafruit_GFX library-style fonts and options, which sends the formatted text as graphics. You can read all about what the library can do in this succinct list of concise functions.

But [Larry] hasn’t stopped there. While experimenting with microcontrollers and BLE thermal printers, he also wanted to explore talking to these printers from his Mac using BLE directly. Print2BLE is a MacOS application that allows dragging image files into the application’s window, and if the preview looks good, the print button makes it come out of the printer as a 1-bpp dithered image.

Small thermal printers make for neat projects, like this retrofitted Polaroid camera, and now that these little printers are both wireless and economical, things can only get easier with the help of a library like this. Of course, if that’s all starting to look a little too easy, one can always put the thermal back in thermal printing by using plasma, instead.