Typing By Slamming Your Laptop Closed. Repeatedly

Do you sometimes feel that your custom mechanical keyboard is not quite loud enough to proclaim your superior hacking powers? Or do you need a more forceful way shout in all caps at someone who is wrong on the internet? For all this and more, [Jesse Li] has got you covered, with a set of bash scripts that allows you to type by slamming your laptop closed repeatedly, using Morse code.

Not the fastest way to type, but definitely the most forceful

The scripts are quite simple, and work receiving the lid open/close events from ACPI (Advanced Configuration and Power Interface), recording the open and close timestamp and converting the timing to dots and dashes. After slamming to the required rhythm, you keep the lid open to see the character appear.

Why would want this? Well, you can now type the letter E by closing your laptop, instead of locking it. Maybe use it to send an emergency message while you’re being held by terrorists in a B-grade action movie. Otherwise, we think this is just an entertaining little hack that’s probably the product of quarantine induced boredom.

Morse code, otherwise known as CW, is still in surprisingly widespread use by ham radio operators, because it’s good at getting messages across intercontinental distances when signal conditions are bad and CW-only ham radio gear is cheap and easy to build yourself. We’ve also covered the Koch Method of learning CW, so don’t be afraid to dabble a bit during the quarantine.

Autonomous 3D Rover With Tank Tracks Rules The Fields. Almost

Scope creep is a real pain in the real world, but for projects of passion it can have some interesting consequences. [rctestflight] was playing around with 3D printed rover gearboxes, which morphed into a 3D printed tank build.

[rctestflight]’s previous autonomous rover project had problems with the cheap geared motors, and he started experimenting with his own gearbox designs to use with lower RPM / Kv brushless drone motors. The tank came about because he wanted a simple vehicle to test his design. “Simple” went out the window pretty quickly and the final product was completely 3D printed except for the fasteners, axles, bearings, and electronics.

The tracks and gears are noisy, but it works quite well. On outdoor tests [rctestflight] did find that the tracks were prone to hooking on vines and branches, which in one case caused it to throw a track after the aluminium shaft bent. An Ardurover navigation system was added and with a 32 Ah battery was able to run autonomously for an entire day and there was surprisingly little wear on 3D printed gearbox and tracks afterward. All the STL files are up on Thingiverse, but [rctestflight] recommends waiting for an upcoming update because he discovered flaws in the design after filming the video after the break.

For a slightly more complex and expensive rover, check out our coverage of Perseverance, NASA’s MARS 2020 Rover. Continue reading “Autonomous 3D Rover With Tank Tracks Rules The Fields. Almost”

Equipping A Workshop Using Plywood And Handheld Power Tools

Properly equipping a home workshop for the DIY discipline of your choice can often end up costing more than we would like to admit, and is a never ending process. [JSK-Koubou] is doing exactly that, except he is building almost all of his equipment using plywood, hand-held power tools and a LOT of attention to detail.

As far as we can tell the series really got started with a humble hand-held circular saw guide, with every tool being used to build more tools. So far the list boasts more than 50 different videos of tools built around a drill, circular saw, jigsaw, router, planar or grinder. This includes a wood lathe, drill press, jointer and various drills guides and sanders. The level of precision each tool almost eye watering. He even pulls out a dial gauge on some builds to check alignment. We honestly didn’t know plywood equipment could look this good and work so well. Check out the YouTube playlist after the break to see for yourself.

Previously we also covered [JSK-Koubou]’s set of perfectly tuned wooden speaker enclosures, the craftsmanship is really something to behold. For more impressive homebuilt hardware, take a look at this 8-axis camera crane built by another YouTuber for his home shop. Continue reading “Equipping A Workshop Using Plywood And Handheld Power Tools”

Compliant Quadruped Legs Using Servos

Walking robots that move smoothly are tricky to build and usually involve some sort of compliant leg mechanism — a robot limb that can rebound like natural physiology for much better movement than what a stiff machine can accomplish. In his everlasting quest to build a real working robot dog, [James Bruton] is working on an affordable and accessible Mini Robot Dog, starting with the compliant leg mechanism.

The 3D printed leg mechanism has two joints (hip and knee), with an RC servo to drive each. To make the joints compliant, both are spring-loaded to absorb external forces, and the deflection is sensed by a hall effect sensor with moving magnets on each side. Using the inputs from the hall effect sensor, the servo can follow the deflection and return to its original position smoothly after the force dissipates. This is a simple technique but it shows a lot of promise. See the video after the break.

A project can sometimes develop a life of its own, or in the case of [James]’s OpenDog, spawn experimentally evolving offspring. This is number four, and it’s designed  to be a platform for learning how to make a quadruped walk properly, and to be simple and cheap enough for others to build. We’re looking forward to seeing how it turns out.

If you missed it, also check out this robot’s weird sibling, self-balancing Sonic.

Continue reading “Compliant Quadruped Legs Using Servos”

Screwy Math For Super Fine Adjustments: Differential Screws

For any sort of precision machine, precision adjustability is required. For the hacker this usually involves an adjustment screw, where the accuracy is determined by the thread pitch. This was not good enough for [Mark Rehorst] who wanted adjustment down to 10 μm for his 3D printer’s optical end-stop, so he made himself a differential adjustment screw.

Tiny adjustment can be made to the green block due to the thread pitch differences

Differential screws work by having two threads with a slightly different pitch on the same shaft. A nut on each section of thread is prevented from rotating in relation to the other, and when the screw is turned their relative position will change only as much as the difference between the two thread pitches.

The differential screw in this case started life as a normal M5 bolt with a 0.8 mm thread pitch. [Mark] machined and threaded section of the bolt down to a M4 x 0.7 mm thread. This means he can get 0.1 mm (100 μm) of adjustment per full rotation. By turning the bolt 1/10 rotation, the  relative movement comes down to 10 μm.

This mechanism is not new, originating from at least 1817. If you need fine adjustments on a budget, it’s a very elegant way to achieve it and you don’t even need a lathe to make your own. You can partially drill and tap a coupling nut, or make a 3D printed adapter to connect two bolts.

Fabricating precision tools on a budget is challenging but not impossible. We’ve seen some interesting graphite air bearings, as well as a 3D printed microscope with a precision adjustable stage.

Pop A Wheelie With Your Electric Skateboard, The Hacker Way

Using a bit of tech to make up for a lack of skill is a time-honoured tradition, otherwise known as cheating among those who acquired the skill the hard way. Learning to wheelie manual a skateboard is usually paid for in bruises, but [blezalex] got around that by letting his electric skateboard handle the balancing act.

At first glance the board looks and rides like an average DIY electric skateboard, with an off-the-shelf  a dual hub motor truck, VESC speed controllers and a wireless throttle. The party trick appears when the front wheel is popped off the ground, which activates the secret self-balancing mode. At this point a STM32F401 dev board and MPU-6050 IMU take over control of the motors, which is in turn controlled by leaning forward or backwards, like a hoverboard. The remote throttle turns into a dead man switch, which cuts power to the motors when released.

[blezalex] says he has had less that an hour of skateboard time in his life before getting on this one, which is a good testament of just how well it works. The biggest challenge was in getting the board to turn while on two wheels, which was solved by sensing side-to-side tilt of the board with the IMU and applying proportional differential torque to the wheels. With a bit of practice it’s also possible to smoothly shift between riding modes while moving.

We think this is a really elegant cheat, now we need to build one of our own. Fortunately the STM32 firmware and instructions are all up on GitHub. Building your own electric skateboard has become really simple with the availability of off-the-shelf components. We’ve also seen a bicycle with a wheelie cheat device to prevent you falling on your back

Silo Launched Model Rocket Goes Thoomp

While rockets launched from silos are generally weapons of war, [Joe Barnard] of [BPS.Space] thought model rocketry could still do with a little more thoomp. So he built a functional tube launched model rocket.

Like [Joe]’s other rockets, it features a servo-actuated thrust vectoring system instead of fins for stabilization. The launcher consists of a 98 mm cardboard tube, with a pneumatic piston inside to eject the rocket out of the tube before it ignites its engine in mid-air. When everything works right, the rocket can be seen hanging motionlessly in the air for a split second before the motor kicks in.

The launcher also features a servo controlled hatch, which opens before the rocket is ejected and then closes as soon as the rocket is clear to protect the tube. The rocket itself is recovered using a parachute, and for giggles he added a tiny Tesla Roadster with its own parachute.

Projects as complex as this rarely work on the first attempt, and Thoomp was no exception. Getting the Signal flight computer to ignite the rocket motors at the correct instant proved challenging, and required some tuning on how the accelerometer inputs were used to recognize a launch event. The flight computer is also a very capable data logger, so every launch attempt, failed or successful, became a learning opportunity. Check out the second video after the break for a fascinating look at how all this data was analyzed.

[Joe]’s willingness to fail quickly and repeatedly as part of the learning process is a true display of the hacker spirit. We’ll definitely be keeping a close eye on his work.

Continue reading “Silo Launched Model Rocket Goes Thoomp