Author: Danie Conradie

426 Articles

3D Printed CNC Knee Mill

July 13, 2021 by 52 Comments

CNC mills will never match real heavy metal mills on hard materials, but that won’t stop people from pushing the limits of these DIY machines. One of the usual suspects, [Ivan Miranda] is at it again, this time building a knee mill from aluminum extrusions and 3D printed fittings. (Video after the break.)

Most DIY CNC milling machines we see use a gantry arrangement, where the bed is fixed while everything else moves around it. On most commercial metal milling machines, the table is the moving part, and are known as knee mills. In the case of [Ivan]’s mill, the table can move 187 mm on the X-axis and 163 mm on the Y-axis. The 1.5 kW spindle can move 87 mm in the Z-axis. All axes slide on linear rails and are driven by large stepper motors using ball screws. The table can also be adjusted in the Z-direction to accept larger workpieces, and the spindle can be tilted to mill at an angle.

To machine metal as [Ivan] intended, rigidity is the name of the game, and 3D printed parts and aluminum extrusion will never be as rigid as heavy blocks of steel. He says claims that the wobble seen on the video is due to the uneven table on which the mill was standing. Of course, a wobbly base won’t be doing him any favors. [Ivan] also had some trouble with earthing on the spindle. He nearly set his workshop on fire when he didn’t notice tiny sparks between the cutter and aluminum workpiece while he was cooling it with isopropyl alcohol. This was solved with the addition of the grounding wire.

While the machine does have limitations, it does look like it can machine functional metal parts. It could even machine metal upgrades for its 3D printed components. One possible way to improve rigidity would be to cast the frame in concrete. [Ivan] has built several other workshop tools, including a massive 3D printer and a camera crane. Continue reading “3D Printed CNC Knee Mill” →

Wing Can Expand To Fly Really Slow For Short Take-Off And Landing

July 10, 2021 by 56 Comments

[Mike Patey] had made a name for himself by building high-performance experimental aircraft. In his latest project, he added a transforming wing that can extend its chord by up to 16 inches for low speed and high angle of attack performance.

The aircraft in question, a bush plane named Scrappy, has been attracting attention long before [Mike] even started building the wings. Designed for extremely short take-off and landing (STOL) performance, only some sections of the fuselage frame remain from the original Carbon Cub kit. The wings are custom designed and feature double slats on the leading edge, combined with large flaps and drooping ailerons on the trailing edge. The slats form an almost seamless part of the wing for normal flying, but can expand using a series of linkages integrated into each precision machine wing rib. Making extensive use of CFD simulations, the slats were designed to keep the center-of-lift close to the center of the wing, even with 50 degrees of flaps. Without the slats, the pilot would need to use almost all the elevator authority to counteract the flaps and keep the aircraft’s nose up.

Leading-edge slats have been around since before WW2, but you don’t see them used in pairs like this. Aircraft like Scrappy will never be commercially viable, but innovation by people like [Mike] drives aviation forward. [Mike]’s previous project plane, Draco, was a large turboprop bush plane built around a PZL-104 Wilga. Sadly it was destroyed during an ill-considered take-off in 2019, but [Mike] is already planning its successor, Draco-X. Continue reading “Wing Can Expand To Fly Really Slow For Short Take-Off And Landing” →

Eliminate Vertical Stabiliser With ArduPlane

July 9, 2021 by 5 Comments

Flying wings are popular options for fixed-wing FPV flying, but they have one rather annoying characteristic: yaw wag. The flying wing will wobble on the yaw axis while flying, and this side-to-side movement is visible on the pilot’s FPV video feed. With a combination of split rudders and ArduPilot, [Think Flight] eliminated wing wag without using any vertical stabilizers.

Yaw wag usually occurs on flying wings that use a pair of small winglets instead of a large vertical stabilizer on the centerline. Split rudders, also known as differential spoilers, can be used for active yaw control by increasing drag on either wing independently. However, this requires very rapid corrections that are very difficult to do manually, so this is where ArduPilot comes in. [Think Flight] used its yaw dampening feature in combination with differential spoilers to completely eliminate vertical stabilizers and yaw wag. This is the same technique used on the B-2 stealth bomber to avoid radar reflecting vertical stabilizers. [Think Flight] also used these clamshells spoilers as elevons.

Using XFLR5 airfoil analysis software, [Think Flight] designed built a pair of flying wings to use these features. The first was successful in eliminating yaw wag, but exhibited some instability on the roll axis. After taking a closer look at the design with XFLR5, he found air it predicted that airflow would separate from the bottom surface of the wing at low angles of attack. After fixing this issue, he built a V2 to closely match the looks of the B2 bomber. Both aircraft were cut from EPP foam with an interesting-looking CNC hot wire cutter and laminated with Kevlar for strength. Continue reading “Eliminate Vertical Stabiliser With ArduPlane” →

Recognising Bird Sounds With A Microcontroller

July 6, 2021 by 4 Comments

Machine learning is an incredible tool for conservation research, especially for scenarios like long term observation, and sifting through massive amounts of data. While the average Hackaday reader might not be able to take part in data gathering in an isolated wilderness somewhere, we are all surrounded by bird life. Using an Arduino Nano 33 BLE Sense and an online machine learning tool, a team made up of [Errol Joshua], [Ajith KJ], [Mahesh Nayak], and [Supriya Nickam] demonstrate how to set up an automated bird call classifier.

The Arduino Nano 33 BLE Sense  is a fully featured little dev board that features the very capable NRF52840 microcontroller with Bluetooth Low Energy, and a variety of onboard sensors, including a microphone. Training a machine learning model might seem daunting to many people, but online services like Edge Impulse makes the process very beginner-friendly. Once you start training your own models for specific applications, you quickly learn that building and maintaining a high quality dataset is often the most time-consuming part of machine learning. Fortunately for this use case, a massive online library of bird calls from all over the world is available on Xeno-Canto. This can be augmented with background noise from the area where the device will be deployed to reduce false-positives. Edge Impulse will train the model using the provided dataset, and generate a library that can be used on the Arduino with one of the provided sample sketches to log and send the collected data to a server. Then comes the never ending process of iteratively testing and improving the recognition model. Edge Impulse is also compatible with more powerful devices such as the Raspberry Pi and Jetson Nano if you want more intensive machine learning models.

We’ve also seen the exact same setup get used for smart baby monitor. If you want to learn more, be sure to watch at [Shawn Hymel]’s talk from the 2020 Remoticon about machine learning on microcontrollers. Continue reading “Recognising Bird Sounds With A Microcontroller” →

See-Through Carburetor Gives A Clear Demonstration

July 6, 2021 by 19 Comments

Carburetors have been largely phased out on most automobiles, but for a century they were the standard, and still are on many smaller engines. Armed with a high-speed camera and with the help of his father, [Smarter Every Day] investigates these devices by experimenting with a DIY see-through carburetor connected to a real engine.

The purpose of a carburetor is to mix gasoline and oxygen to the correct ratio for combustion inside the engine. Gasoline flow from the tank to the bowl, from where gets sucked into the venturi. The choke valve adjusts the amount of air entering the carb, while the throttle controls the amount of air-fuel mixture entering the engine. It appears that the carburetor was made from a resin 3D printed body and manifold, with an acrylic cover and PLA throttle and choke valves. It was attached to a single-cylinder engine.

The high-speed footage is incredible, and clearly shows the operation of the carburetor and makes it incredibly easy to understand. If you’re interested, he also uploaded a second video with almost 80 minutes of detailed footage.

[Smarter Every Day]’s infectious curiosity has led to numerous fascinating projects, including a supersonic baseball canon and the backward bicycle.

Continue reading “See-Through Carburetor Gives A Clear Demonstration” →

Open Source Ultrasonic Anemometer

July 6, 2021 by 12 Comments

Weather stations are a popular project for experimenting with various environmental sensors, and for wind speed and direction the choice is usually a simple cup anemometer and wind vane. For [Jianjia Ma]’s QingStation, he decided to build another type of wind sensor: An ultrasonic anemometer.

Ultrasonic anemometers have no moving parts but come at the cost of significantly more electronic complexity. They work by measuring the time it takes for an ultrasonic audio pulse to be reflected the receiver across a known distance. Wind direction can be calculated by taking velocity readings from two ultrasonic sensor pairs perpendicular to each other and using a bit of simple trigonometry. For an ultrasonic anemometer to work properly, it requires a carefully designed analog amplifier on the receive side and a lot of signal processing to extract the correct signal from all the noise caused by secondary echoes, multi-pathing, and the environment. The design and experimentation process is well-documented. Since [Jianjia] does not have access to a wind tunnel for testing and calibration, he improvised by mounting the anemometer on his car’s roof and going for a drive. This yielded readings that were proportional to the car’s GPS speed, but a bit higher. This might due to a calculation error, or external factors like wind, or disturbed airflow from the test car or other traffic.

Other sensors include an optical rain sensor, light sensor, lighting sensor, and a BME280 for air pressure, humidity, and temperature. [Jianjia] plans to use the QingStation on an autonomous boat, so he also included an IMU, compass, GPS, and a microphone for environmental sounds. The fact that none of the sensors have moving parts is a major advantage for this use case, and we look forward to seeing the boat project. All the hardware and software are open-source and available on GitHub.

Continue reading “Open Source Ultrasonic Anemometer” →

Bellow-Cooled PC Is A Well Engineered Display Piece

July 6, 2021 by 19 Comments

The cooling systems on high-performance PCs are often a large part of their visual appeal, but we’ve never seen anything like [DIY Perks]’ latest build: A massive bellow-cooled PC.

The system is derived from a silent bellow system built by [DIY Perks] in 2020. It uses a clever combination of hydraulics and neodymium magnets to smoothly reciprocate a large plate within a chamber. Instead of blowing the air straight into the room, it pushes it through a pair of wood ducts into a second chamber with PC components, and out through a water-cooling radiator. To prevent the hot air from being sucked back in as the bellow reciprocates, a row of check valves was added on each side of the PC chamber and at the external intakes. The sides of the bellow chamber and PC chamber are made of glass to allow a full view of the internal components.

The build was not without complications. While disassembling the old bellow, the acrylic tube in which the magnet reciprocates shattered. When a replacement rube arrived, [DIY Perks] discovered the magnet’s fit was very loose. He solved this by increasing the thickness of the magnet’s nickel coating with another run of electroplating. To achieve a uniform coating, he agitated the plating solution by suspending the magnet from a small speaker playing a sine-wave tone. The cooling performance is excellent, keeping the CPU and GPU at 60C or below, even while running them at full tilt.

Continue reading “Bellow-Cooled PC Is A Well Engineered Display Piece” →