Author: Danie Conradie

427 Articles

Building A Robotic Band To Make Up For Lack Of Practice

May 6, 2021 by 6 Comments

Learning to play a musical instrument well requires a significant time investment. [Ivan Miranda] had dreamt of doing this but made peace with the fact that his talents and motivation lay in building machines. However, he has decided to play to his strengths and is building a robotic band. See the videos after the break.

So far he has mechanized a hi-hat, snare drum, and a very basic guitar. The guitar is nothing more than a single string stretched across an aluminum frame, with an electronic pickup. Most of the work has gone into the solenoid-driven picking mechanism. He wanted to avoid picking the string when the solenoid is turned of, so he created a simple little mechanism that only comes in contact with the string when it’s moving in one direction. A bistable solenoid might be a simpler option here.

For the high hat, [Ivan] built a custom stand with two bistable solenoids to lift and drop the top cymbal. A solenoid-driven drumstick was also added. The snare drum uses a similar mechanism, but with a larger solenoid. So far he hasn’t really worked on a control system, focusing mainly on electronics.

[Ivan] points out several times that he has knows very little about making music, but we do enjoy watching him explore and experiment with this new world. Usually, his projects involve a lot more 3D printing, like when he built a giant nerf bazooka or a massive 3D printed tank. Continue reading “Building A Robotic Band To Make Up For Lack Of Practice” →

Learn Engineering Concepts With Some Cool Animations

May 5, 2021 by 5 Comments

All feats of engineering build on a proper understanding of the basic engineering concepts. Learning these concepts from a book or class tends to be a rather uninspiring exercise, unfortunately. To make this task a lot more enjoyable, [The Efficient Engineer] has produced a series of high-quality, easy-to-watch videos on the concepts.

The videos focus mainly on mechanical and structural engineering and contain excellent animations and just enough math to give you a basic understanding. There are 22 videos so far and cover a wide variety of topics, including FEA analysis, stress and strain, aerodynamics, and Young’s modulus. Each video starts with the basics, then digs down into the topic, all the while visualizing the subject being discussed. For example, for FEA he starts with the applications, then covers discretization (meshing) and how to solve the calculations.

For more excellent educational videos, check out [Real Engineering] and [Practical Engineering]. Continue reading “Learn Engineering Concepts With Some Cool Animations” →

A Wireless Speaker Pair From Dead Earbuds

May 5, 2021 by 23 Comments

Building a Bluetooth speaker is easy with the availability of cheap Bluetooth receivers, but surprisingly there isn’t a simple way to build a pair of truly wireless stereo speakers. [Matt] from DIY Perks realized that modern Bluetooth earbuds contain all the electronics to do just that.

Due to the popularity of these earbuds, a broken pair can be picked up very cheaply on eBay. Usually, it’s only the battery or speaker unit that give out, neither of which are required for this build. [Matt] goes through the process of taking a pair of earbuds apart, and then soldering on battery and speaker wires. The speaker wires are connected to an audio amp, which drives a mid-range and treble speaker driver, and a subwoofer. The outputs to the amp are also filtered to match the speakers. Power is provided by a set of four 18650 cells.

[Matt] housed the driver and electronics in some attractive CNC machined wood enclosures. In the video, he places a lot of emphasis on properly sealing all the gaps to get the best possible audio quality. As with all of his projects, the end result looks and performs like a high-end commercial product. We’re almost surprised that he didn’t add any brass to the speakers, as he did on his USB-C monitor or PS5 enclosure build. Continue reading “A Wireless Speaker Pair From Dead Earbuds” →

A DIY Enclosed Motorcycle To Keep You Dry In The Rain

May 5, 2021 by 41 Comments

Motorcyclist’s vulnerability to bodily harm and weather has spawned several enclosed motorcycle designs over the years. Fascinated by the idea, [Meanwhile in the garage] finally got around to building his own. (Video, embedded below.)

The vehicle started life as a 125cc scooter, stripped of all the unnecessary bits, he welded a steel cockpit onto it. A windshield, doors, and side windows were also added. The ends of the handlebars were cut off and reattached at 90 degrees to fit inside the narrow cockpit. A pair of retractable “training wheels” keep the vehicle upright and at slow speeds.

Legalities aside, we can’t help but think that the first test drives should not have been on a public road. It almost ended in disaster when a loose axle nut on the front wheel caused steering oscillations which caused the vehicle to tip over. Fortunately, there were no injuries and only light cosmetic damage, so a more successful test followed the first.

While many companies have tried, enclosed motorcycles have never achieved much commercial success. Probably because they inhabit a no-mans-land between the rush and freedom of riding a motorcycle and the safety and comfort of a car.

For some less extreme conversion, check out this electric motorcycle, or a rideable tank track.

Continue reading “A DIY Enclosed Motorcycle To Keep You Dry In The Rain” →

3D Printed Camera Crane For The Workshop

May 5, 2021 by 7 Comments

When you make a living building stuff and documenting the process camera setups take up a lot of time, breaking expensive equipment is an occupational hazard. [Ivan Miranda] knows this all too well, so he built a fully-featured camera crane to save his time and camera equipment. Video after the break.

The basic design is a vertical mast with a pivoting camera mounted to the end. The aluminum mast telescopes for increased vertical adjustability, and rides on a plywood base with caster wheels. The aluminum pivoting arm is counterweighed to offset the camera head, and a parallel bar mechanism allows the camera to hold a constant vertical angle with the ground. Thanks to the explosion of home gyms during the pandemic, gym weights were hard to find, so [Ivan] used an ammo can filled with sand and screws instead. A smaller sliding counterweight on top of the arm allows for fine-tuning. [Ivan] also wanted to be able to do horizontal sliding shots, so he added a pulley system that can be engaged with a clutch mechanism to keep a constant horizontal angle with the camera. Most of the fittings and brackets are 3D printed, some of them no doubt on his giant 3D printer.

We can certainly see this crane meeting its design objectives, and we can’t help but want one ourselves. [Alexandre Chappel] also built a camera crane a while back which utilized a completely different arm mechanism. As cool as these are, they still pale in comparison to [mingul]’s workshop-sized 8-axis CNC camera crane. Continue reading “3D Printed Camera Crane For The Workshop” →

Prioritising Mechanical Multiplexer

May 4, 2021 by 17 Comments

When automating almost any moderately complex mechanical task, the actuators and drive electronics can get expensive quickly. Rather than using an actuator for every motion, mechanical multiplexing might be an option. [James Bruton] has considered using it in some of his many robotics projects, so he built a prioritizing mechanical multiplexer to demonstrate the concept.

The basic idea is to have a single actuator and dynamically switch between different outputs. For his demonstration, [James] used a motor mounted on a moving platform actuated by a lead screw that can engage a number of different output gears. Each output turns a dial, and the goal is to match the position of the dial to the position of a potentiometer. The “prioritizing” part comes in where a number of outputs need to be adjusted, and the system must choose which to do first. This quickly turns into a task scheduling problem, since there are a number of factors that can be used to determine the priority. See the video after the break to see different algorithms in action.

Instead of moving the actuator, all the outputs can connect to a single main shaft via clutches as required. Possible use cases for mechanical multiplexers include dispensing machines and production line automation. Apparently, the Armatron robotic arm sold by Radioshack in the ’80s used a similar system, controlling all its functions with a single motor.

[James] knows or two about robotics, having built many of them over the last few years. Just take a look at OpenDog and his Start Wars robots. Continue reading “Prioritising Mechanical Multiplexer” →

Robotic Gripper From A Squishy Ball

May 4, 2021 by 11 Comments

Soft robotic grippers have some interesting use cases, but the industrial options are not cheap. [James Bruton] was fascinated by the $4000 “bean bag” gripper from Empire Robotics, so he decided to build his own.

The gripper is just a flexible rubber membrane filled with small beads. When it is pushed over a object and the air is sucked out, it holds all the beads together, molded to the shape of the object. For his version [James] used a soft rubber ball filled with BBs. To create a vacuum, he connected a large 200cc syringe to the ball via a hose, and actuated it with a high torque servo.

It worked well for small, light objects but failed on heavier, smooth objects with no edges to grip onto. This could possibly be improved if the size and weight of the beads/BBs are reduced.

For some more soft robotics, check out this soft 3D printed hand, and the flexible electrically driven actuators. Continue reading “Robotic Gripper From A Squishy Ball” →