Author: Aaron Beckendorf

91 Articles

A grey and blue coreXY 3D printer is shown, with a small camera in place of its hotend. On the print bed is a ChArUco pattern, a grid of square tiles containing alternating black fill and printed patterns.

Calibrating A Printer With Computer Vision And Precise Timing

December 22, 2025 by 17 Comments

[Dennis] of [Made by Dennis] has been building a Voron 0 for fun and education, and since this apparently wasn’t enough of a challenge, decided to add a number of scratch-built improvements and modifications along the way. In his latest video on the journey, he rigorously calibrated the printer’s motion system, including translation distances, the perpendicularity of the axes, and the bed’s position. The goal was to get better than 100-micrometer precision over a 100 mm range, and reaching this required detours into computer vision, clock synchronization, and linear algebra.

To correct for non-perpendicular or distorted axes, [Dennis] calculated a position correction matrix using a camera mounted to the toolhead and a ChArUco board on the print bed. Image recognition software can easily detect the corners of the ChArUco board tiles and identify their positions, and if the camera’s focal length is known, some simple trigonometry gives the camera’s position. By taking pictures at many different points, [Dennis] could calculate a correction matrix which maps the printhead’s reported position to its actual position.

Continue reading “Calibrating A Printer With Computer Vision And Precise Timing” →

A browser window is shown, in which a web page is displaying a green trace of a square wave.

A Compact, Browser-Based ESP32 Oscilloscope

December 21, 2025 by 34 Comments

An oscilloscope is usually the most sensitive, and arguably most versatile, tool on a hacker’s workbench, often taking billions of samples per second to produce an accurate and informative representation of a signal. This vast processing power, however, often goes well beyond the needs of the signals in question, at which point it makes sense to use a less powerful and expensive device, such as [MatAtBread]’s ESP32 oscilloscope.

Continue reading “A Compact, Browser-Based ESP32 Oscilloscope” →

A device within a vertical rectangular frame is shown, with a control box on the front and an LCD display. Within the frame, a grid of syringes is seen held upright beneath two parallel plates.

Building A Multi-Channel Pipette For Parallel Experimentation

December 20, 2025 by 6 Comments

One major reason for the high cost of developing new drugs and other chemicals is the sheer number of experiments involved; designing a single new drug can require synthesizing and testing hundreds or thousands of chemicals, and a promising compound will go through many stages of testing. At this scale, simply performing sequential experiments is wasteful, and it’s better to run tens or hundreds of experiments in parallel. A multi-channel pipette makes this significantly simpler by collecting and dispensing liquid into many vessels at once, but they’re, unfortunately, expensive. [Triggy], however, wanted to run his own experiments, so he built his own 96-channel multi-pipette for a fiftieth of the professional price.

The dispensing mechanism is built around an eight-by-twelve grid of syringes, which are held in place by one plate and have their plungers mounted to another plate, which is actuated by four stepper motors. The whole syringe mechanism needed to move vertically to let a multi-well plate be placed under the tips, so the lower plate is mounted to a set of parallel levers and gears. When [Triggy] manually lifts the lever, it raises the syringes and lets him insert or remove the multi-well. An aluminium extrusion frame encloses the entire mechanism, and some heat-shrink tubing lets pipette tips fit on the syringes.

[Triggy] had no particularly good way to test the multi-pipette’s accuracy, but the tests he could run indicated no problems. As a demonstration, he 3D-printed two plates with parallel channels, then filled the channels with different concentrations of watercolors. When the multi-pipette picked up water from each channel plate and combined them in the multi-well, it produced a smooth color gradient between the different wells. Similarly, the multi-pipette could let someone test 96 small variations on a single experiment at once. [Triggy]’s final cost was about $300, compared to $18,000 for a professional machine, though it’s worth considering the other reason medical development is expensive: precision and certifications. This machine was designed for home experiments and would require extensive testing before relying on it for anything critical.

Continue reading “Building A Multi-Channel Pipette For Parallel Experimentation” →

A blue screen is visible, with an ASCII image of the text "Hello World" is displayed.

Designing A CPU For Native BASIC

December 17, 2025 by 22 Comments

Over the years there have been a few CPUs designed to directly run a high-level programming language, the most common approach being to build a physical manifestation of a portable code virtual machine. An example might be the experimental Java processors which implemented the JVM. Similarly, in 1976 Itty Bitty Computers released an implementation of Tiny BASIC which used a simple virtual machine, and to celebrate 50 years of Tiny BASIC, [Zoltan Pekic] designed a CPU that mirrors that VM.

The CPU was created within a Digilent Anvyl board, and the VHDL file is freely available. The microcode mapping ROM was generated by a microcode compiler, also written by [Zoltan]. The original design could execute all of the 40 instructions included in the reference implementation of Tiny BASIC; later iterations extended it a bit more. To benchmark its performance, [Zoltan] set the clock rate on the development board equal to those of various other retrocomputers, then compared the times each took to calculate the prime numbers under 1000 using the same Tiny BASIC program. The BASIC CPU outperformed all of them except for Digital Microsystems’ HEX29. Continue reading “Designing A CPU For Native BASIC” →

Liberating AirPods With Bluetooth Spoofing

December 12, 2025 by 18 Comments

Apple’s AirPods can pair with their competitors’ devices and work as basic Bluetooth earbuds, but to no one’s surprise most of their really interesting features are reserved for Apple devices. What is surprising, though, is that simple Bluetooth device ID spoofing unlocks these features, a fact which [Kavish Devar] took advantage of to write LibrePods, an AirPods controller app for Android and Linux.

In particular, LibrePods lets you control noise reduction modes, use ear detection to pause and unpause audio, detect head gestures, reduce volume when the AirPods detect you’re speaking, work as configurable hearing aids, connect to two devices simultaneously, and configure a few other settings. The app needs an audiogram to let them work as hearing aids, and you’ll need an existing audiogram – creating an audiogram requires too much precision. Of particular interest to hackers, the app has a debug mode to send raw Bluetooth packets to the AirPods. Unfortunately, a bug in the Android Bluetooth stack means that LibrePods requires root on most devices.

This isn’t the first time we’ve seen a hack enable hearing aid functionality without official Apple approval. However, while we have some people alter the hardware, AirPorts can’t really be called hacker- or repair-friendly.

Thanks to [spiralbrain] for the tip!

A man's hands are holding an assembly of 3D-printed parts. There is a white backplate, with a yellow circular piece running through the middle. The yellow piece is surrounded by metal rods. Another blue shaft runs through the left side of the assembly. A rougly-diamond shaped plate encompasses both of these shafts.

Designing A Simpler Cycloidal Drive

December 11, 2025 by 1 Comment

Cycloidal drives have an entrancing motion, as well as a few other advantages – high torque and efficiency, low backlash, and compactness among them. However, much as [Sergei Mishin] likes them, it can be difficult to 3D-print high-torque drives, and it’s sometimes inconvenient to have the input and output shafts in-line. When, therefore, he came across a video of an industrial three-ring reducing drive, which works on a similar principle, he naturally designed his own 3D-printable drive.

The main issue with 3D-printing a normal cycloidal drive is with the eccentrically-mounted cycloidal plate, since the pins which run through its holes need bearings to keep them from quickly wearing out the plastic plate at high torque. This puts some unfortunate constraints on the size of the drive. A three-ring drive also uses an eccentric drive shaft to cause cycloidal plates to oscillate around a set of pins, but the input and output shafts are offset so that the plates encompass both the pins and the eccentric driveshaft. This simplifies construction significantly, and also makes it possible to add more than one input or output shaft.

As the name indicates, these drives use three plates 120 degrees out of phase with each other; [Sergei] tried a design with only two plates 180 degrees out of phase, but since there was a point at which the plates could rotate just as easily in either direction, it jammed easily. Unlike standard cycloidal gears, these plates use epicycloidal rather than hypocycloidal profiles, since they move around the outside of the pins. [Sergei] helpfully wrote a Python script that can generate profiles, animate them, and export to DXF. The final performance of these drives will depend on their design parameters and printing material, but [Sergei] tested a 20:1 drive and reached a respectable 9.8 Newton-meters before it started skipping.

Even without this design’s advantages, it’s still possible to 3D-print a cycloidal drive, its cousin the harmonic drive, or even more exotic drive configurations. Continue reading “Designing A Simpler Cycloidal Drive” →

A circular 3D-printed board is shown, with a roughly star-shaped pattern of white LEDs glowing through the surface. Yellow and green LEDs are also visible through the surface at a few points.

Adding Electronics To A Classic Game

December 5, 2025 by No comments

Like many classic board games, Ludo offers its players numerous opportunities to inflict frustration on other players. Despite this, [Viktor Takacs] apparently enjoys it, which motivated him to build a thoroughly modernized, LED-based, WiFi-enabled game board for it (GitHub repository).

The new game board is built inside a stylish 3D-printed enclosure with a thin white front face, under which the 115 LEDs sit. Seven LEDs in the center represent a die, and the rest mark out the track around the board and each user’s home row. Up to six people can play on the board, and different colors of the LEDs along the track represent their tokens’ positions. To prevent light leaks, a black plastic barrier surrounds each LED. Each player has one button to control their pieces, with a combination of long and short presses serving to select one of the possible actions.

The electronics themselves are mounted on seven circuit boards, which were divided into sections to reduce their size and therefore their manufacturing cost. For component placement reasons, [Viktor] used a barrel connector instead of USB, but for more general compatibility also created an adapter from USB-C to a barrel plug. The board is controlled by an ESP32-S3, which hosts a server that can be used to set game rules, configure player colors, save and load games, and view statistics for the game (who rolled the most sixes, who sent other players home most often, etc.).

If you prefer your games a bit more complex, we’ve also seen electronics added to Settlers of Catan. On a rather larger scale, there is also this LED-based board game which invites humans onto the board itself. Continue reading “Adding Electronics To A Classic Game” →