Internet Connected TI-84 To Cut Your Academic Career Short

September 29, 2024 by Danie Conradie 22 Comments

In an educational project with ethically questionable applications, [ChromaLock] has converted the ubiquitous TI-84 calculator into the ultimate cheating device.

The foundation of this hack lies in the TI-84’s link protocol, which has been a mainstay in calculator mods for years. [ChromaLock] uses this interface to connect to a tiny WiFi-enabled XIAO ESP32-C3 module hidden in the calculator. It’s mounted on a custom PCB with a simple MOSFET-based level shifting circuit, and slots neatly into a space on the calculator rear cover. The connecting wires are soldered directly to the pads of the 2.5 mm jack, and to the battery connections for power.

But what does this mod do? It connects your calculator to the internet and gives you a launcher with several applets. These allow you to view images badly pixelated images on the TI-84’s screen, text-chat with an accomplice, install more apps or notes, or hit up ChatGPT for some potentially hallucinated answers. Inputting long sections of text on the calculator’s keypad is a time-consuming process, so [ChromaLock] teased a camera integration, which will probably make use of newer LLMs image input capabilities. The ESP32 doesn’t handle all the heavy lifting, and needs to connect to an external server for more complex interfaces.

To prevent pre-installed programs from being used for cheating on TI-84s, examiners will often wipe the memory or put it into test mode. This mod can circumvent both. Pre-installed programs are not required on the calculator to interface with the hardware module, and installing the launcher is done by sending two variables containing a password and download command to the ESP32 module. The response from the module will also automatically break the calculator out of test mode.

We cannot help but admire [ChromaLock]’s ingenuity and polished implementation, and hopefully our readers are more interested in technical details than academic self-sabotage. For those who need even more capability in their calculator, we’d suggest checking out the NumWorks. Continue reading “Internet Connected TI-84 To Cut Your Academic Career Short” →

Building Robots With A 20×20 Grid

February 5, 2024 by Danie Conradie 15 Comments

On autonomous robots, the most difficult challenges usually lie in the software and electronic realms, but the mechanics can also be very time consuming. To help address this challenge, [Nikodem Bartnik] is working on the Open Robotic Platform (ORP), a modular robotics chassis system designed to make prototyping as easy and affordable as possible. Video after the break.

The ORP is governed by a set of design rules to maintain interchangeability. Most of the design rules are very open, but the cornerstone of ORP is its standardized mounting plates featuring a 20 mm grid pattern of 3.5 mm mounting holes. These plates can be stacked using connecting rods, creating a versatile foundation upon which various components can be mounted.

[Nikodem] is on a mission to create and collect an entire library of these modular components. From custom 3D-printed holders that accommodate sensors, motors, wheels and dev boards to homemade PCBs that snap directly onto the chassis, everything to get your robot rolling as soon as possible. While manufacturing methods and materials are not limited, 3D printing and laser cutting will likely be the most popular manufacturing technologies for making your own parts.

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POP! Goes The Hydrogen Howitzer

February 4, 2024 by Danie Conradie 70 Comments

Military models are great 3D printing projects, even more so if they are somewhat functional. [Flasutie] took it a step further by engineering a 3D-printed howitzer that doesn’t just sit pretty—it launches shells with a hydrogen-powered bang.

This project’s secret sauce? Oxyhydrogen, aka HHO, the mix of hydrogen born when water endures the electric breakup of electrolysis. [Flasutie] wanted functional “high explosive” (HE) projectiles to pop without turning playtime into emergency room visit, and 30 mm was the magic size, allowing the thin-walled PLA projectile to rupture without causing injury, even when held in the hand. To set off the gaseous fireworks, [Flasutie] designed an impact fuze featuring piezoelectric spark mechanism nestled within a soft TPU tip for good impact sensitivity.

The howitzer itself is like something out of a miniaturized military fantasy—nearly entirely 3D printed. It boasts an interrupted thread breech-locking mechanism and recoil-absorbing mechanism inspired by the real thing. The breechblock isn’t just for show; it snaps open under spring power and ejects spent cartridges like hot brass.

Watch the video after the break for the build, satisfying loading sequence and of course cardboard-defeating “armor piercing” (AP) and HE shells knocking out targets.

Transforming EDF Backpack For A Speed Boost

February 3, 2024 by Danie Conradie 18 Comments

Fighting against a tough headwind on your daily cycle can be a drag, but [Emiel] of The Practical Engineer, has a loud and bold solution. In the Dutch video after the break, he builds a transforming backpack with two electric ducted fans (EDFs), and takes to the bike paths.

An EDF moves a small volume of air at high velocity, which doesn’t make them great for low speed applications. But they’re nice and compact, and safer than large propellers. [Emiel] didn’t skimp on the rest of the hardware, with the motors attached to metal 3D printed arms, mounted on a machined aluminum steel plate.

The arms were printed courtesy of a sponsor, and created via generative design in Fusion 360 to make them both light and strong. A pair of large servos swing the arms up, while smaller servos rotate the motors into the horizontal position. The arm servos are controlled by an Arduino, and activated by a simple toggle switch attached to the backpack’s shoulder strap. A wireless remote similar to that of an electric skateboard is used to control the EDFs.

Fitted in a [Emiel]’s old backpack, the result looks somewhat innocuous (if you don’t look too closely) until it unfolds its hidden power—twin jets ready to blast away any pesky headwinds with the push of a button. It’s a fun solution that is sure to attract attention, and a great excuse to create heavy duty mechanics.

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Electric Boomerang Does Laps

February 2, 2024 by Danie Conradie 5 Comments

Boomerangs are known for their unique ability to circle back to the thrower, but what if you could harness this characteristic for powered for free flight? In a project that spins the traditional in a new direction, [RCLifeOn] electrifies a boomerang to make it fly laps.

The project started with several of the 3D printed boomerang designs floating around on the internet, and adding motor mounts to the tips. [RCLifeOn] is no stranger to RC adventures, and his stockpile of spare parts from previous flying and floating projects proved invaluable. He added motor mounts and mounted all the electronics, including a RC receiver for controlling the throttle, but first iteration didn’t have enough lift, so the boomerang and motors were scaled up.

[RCLifeOn] launched the contraptions by letting them spin on the end of a stick until they achieve lift-off. The second iteration still couldn’t quite get into the air, but after increasing the blade angles using a heat gun it was flying laps around the field.

Although we’ve seen spinning drones that are controllable, it would be no small control systems challenge to make it completely RC controlled. In the meantime this project is a fun, if somewhat risky way to mix the traditional with modern tech.

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An Alternative Orientation For 3D Printed Enclosures

February 2, 2024 by Danie Conradie 29 Comments

When it comes to 3D printing, the orientation of your print can have a significant impact on strength, aesthetics, and functionality or ease of printing. The folks at Slant 3D have found that printing enclosures at a 45° provides an excellent balance of these properties, with some added advantages for high volume printing. The trick is to prevent the part from falling over when balance on a edge, but in the video after the break [Gabe Bentz] demonstrate Slant 3D’s solution of minimalist custom supports.

The traditional vertical or horizontal orientations come with drawbacks like excessive post-processing and weak layer alignment. Printing at 45° reduces waste and strengthens the end product by aligning the layer lines in a way that resists splitting across common stress points. When scaling up production, this orientation comes with the added advantage of minimal bed contact area, allowing the printer to auto-eject the part by pushing it off the bed with print head.

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The Case Against Calibration Cubes

February 2, 2024 by Danie Conradie 27 Comments

Calibration cubes have long been a staple for testing and adjusting 3D printers, but according to [Stefan] of CNC Kitchen, they’re not just ineffective—they could be leading us astray. In the video after the break he explains his reasoning for this controversial claim, and provides a viable alternative.

Such cubes are often used to calibrate the steps per millimeter for the printer’s steppers, but the actual dimensions of said cube can be impacted by over or under extrusion, in addition to how far the machine might be out of alignment. This can be further exacerbated by measuring errors due to elephant’s foot, over extruded corners, or just inaccuracies in the caliper. All these potential errors which can go unnoticed in the small 20 x 20 mm cube, while still leading to significant dimensional errors in larger prints

So what’s the solution? Not another cube. It’s something called the “CaliFlower” from [Adam] of Vector 3D. This is not a typical calibration model — it’s carefully designed to minimize measurement errors with ten internal and external measuring points with stops for your calipers. The model costs $5, but for your money you get a complete guide and spreadsheet to calculate the required of corrections needed in your firmware or slicer settings.

If you regularly switch materials in your 3D printer, [Stefan] also advises against adjusting steps per millimeter and suggests defining a scaling factor for each material type instead. With this method validated across different materials like PLA, PETG, ABS, and ASA, it becomes evident that material shrinkage plays a significant role in dimensional inaccuracy, not just machine error. While [Stefan] makes a convincing case against the standard calibration cube for dimensional calibration, he notes that is is still useful for evaluating general print quality and settings.

[Stefan] has always done rigorous testing to back his claims, and this video was no different. He has also tested the effects of filament color on part strength, the practicality of annealing parts in salt, and even printing custom filament.

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