The 3D Printed Guitar

October 10, 2018 by Brian Benchoff 6 Comments

We just wrapped up the Musical Instrument Challenge in the Hackaday Prize, and that means we’re sorting through a ton of inventive electronic musical instruments. For whatever reason we can’t seem to find many non-electronic instruments. Yes, MPCs are cool, but so are strings and vibrating columns of air. That’s what makes this entry special: it’s a 3D printed physical guitar. But it’s also got a hexaphonic pickup, there are lights in the fretboard, and it talks to a computer for PureData processing.

First, the construction of this guitar. It’s mostly 3D printed, with the ‘frame’ of the body made in a Creality 3D printer. It’s a bolt-on neck with a telecaster body, but the core of this guitar — where the pickups and bridge attach — are made out of aluminum extrusion. Another piece of aluminum extrusion runs down the neck, which is clad in a 3D-printed ‘back’ that looks ‘comfortable enough’. The headstock is bolted onto the end of this neck, and it seems reasonably tolerant of having a hundred pounds or so of strings pulling on it. The bridge is also 3D printed, with the saddles integrated into the print. Conventional wisdom says this would sound terrible, but nylon saddles were a thing back in the day, so we’re just going to roll with it.

The electronics are where this project really shines. The pickup is a salvaged Roland GK3 hexaphonic deal, with six outputs for each string. This is sent into a Teensy with an audio path for each individual string. Audio processing happens in the guitar, and latency is under five milliseconds, which is quick enough to not be a terrible distraction.

Except for synths and drum machines and computers, the last fifty or so years of technological progress hasn’t really made it to the world of musical instruments. Guitarists, especially, are technophobes who hate everything invented after 1963. While the neck of [Frank]’s ElektroCaster probably doesn’t feel great, this is a really interesting instrument and a great entry to the Hackaday Prize.

Smartphone Mod Goes Out On A Limb

October 6, 2018 by Lewin Day 24 Comments

The modern smartphone has a variety of ways to interact with its user – the screen, the speakers, and of course, the vibration motor. But what if your phone could interact physically? It might be unnerving, but it could also be useful – and MobiLimb explores exactly this possibility.

Yes, that’s right – it’s a finger for your mobile phone. MobiLimb has five degrees of freedom, and is built using servomotors which allow both accurate movement as well as positional feedback into the device. Additionally, a touch-sensitive potentiometer is fitted, allowing the robofinger to respond to touch inputs.

The brains behind the show are provided by an Arduino Leonardo Pro Micro, and as is usual on such projects, the mechanical assembly is 3D printed – an excellent choice for producing small, complex parts. Just imagine the difficulty of trying to produce robotic fingers with classic machine tools!

The project video shows many different possibilities for using the MobiLimb – from use as a basic notification device, to allowing the smartphone to crawl along a table. We frankly can’t wait until there’s a fully-functional scorpion chassis to drop an iPhone into – the sky really is the limit here.

Interested in other unique ways to interact with your smartphone? Check out these nifty 3D printed physical buttons.

Watch The Snappy, Insect-like Moves Of This DIY Quadruped Robot

September 30, 2018 by Donald Papp 28 Comments

Some legged robots end up moving with ponderous deliberation, or wavering in unstable-looking jerks. A few unfortunates manage to do both at once. [MusaW]’s 3D Printed Quadruped Robot, on the other hand, moves in rapid motions that manage to look sharp and insect-like instead of unstable. Based on an earlier design he made for a 3D printable quadruped frame, [MusaW] has now released this step-by-step guide for building your own version. All that’s needed is the STL files and roughly $50 in parts from the usual Chinese resellers to have the makings of a great weekend project.

The robot uses twelve SG90 servos and an Arduino nano with a servo driver board to control them all, but there’s one additional feature: Wi-Fi control is provided thanks to a Wemos D1 Mini (which uses an ESP-8266EX) acting as a wireless access point to serve up a simple web interface through which the robot can be controlled with any web browser.

Embedded below is a brief video. The first half is assembly, and the second half demonstrates the robot’s fast, sharp movements.

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Man’s Best Robotic Friend

September 17, 2018 by Brian Benchoff 4 Comments

When it comes to robotics, some of the most interesting work — and certainly the most hilarious — has come from Boston Dynamics, and their team of interns kicking robotic dogs over. It’s an impressive feat of engineering, and even if these robotic pack mules are far too loud for their intended use on the battlefield, it’s a great showcase of how cool a bunch of motors can actually be.

It’s not quite up there with the Boston Dynamics robots, but [Dimitris]’ project for the Hackaday Prize is an almost equally impressive assemblage of motors, 3D printed parts, SLAM processing and inverse kinematics. I suppose you could also kick it over and watch it struggle for laughs, too.

This robotic dog was first modeled in Fusion 360, and was designed with 22 Dynamixel AX-12A robot actuators: big, beefy, serial-controllable servos. Of course, bolting a bunch of motors to a frame is the easy part. The real challenge here is figuring out the kinematics and teaching this robot dog how to walk. This is still a work in progress, but so far [Dimitris] is able to move the spine, keep the feet level with the ground, and have the robot walk a little bit. There’s still work to do, but there’s an incredible amount of work that’s already been done.

The upcoming features for this robot include a RealSense camera mounted on the head for 3D visualization of the surroundings. There’s also plans for a tail, loosely based on some of the tentacle robots we’ve seen. It’s going to be a great project when it’s done, and it’s already an excellent entry for the Hackaday Prize.

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DrawBot Badge Represents The CNC World In Badge Design

September 16, 2018 by Donald Papp 14 Comments

Badges come in all shapes and sizes, but a badge that draws on a stack of Post-It notes is definitely a new one. The design uses three of the smallest, cheapest hobby servos reasonably available and has a drawing quality that creator [Bart Dring] describes as “adorably wiggly”. It all started when he decided that the CNC and mechanical design world needed to be better represented in the grassroots demo scene that is the badge world, and a small drawing machine that could be cheaply made from readily available components seemed just the ticket.

Two arms control the position of a pen, and a third motor lifts the assembly in order to raise or lower the pen to the drawing surface. Gravity does most of the work for pen pressure, so the badge needs to be hanging on a lanyard or on a tabletop in order to work. An ESP32 using [Bart]’s own port of Grbl does the work of motion control, and a small stack of Post-It notes serves as a writing surface. Without the 3D printed parts, [Bart] says the bill of materials clocks in somewhere under $12.

We’ve seen similar designs doing things like writing out the time with a UV LED, but a compact DrawBot on a badge is definitely a new twist and the fact that it creates a physical drawing that can be peeled off the stack also sets it apart from others in the badgelife scene.

Cat Robot’s Secret To Slim Legs? Banish The Motors!

September 15, 2018 by Donald Papp 6 Comments

The first thing to notice about [Bijuo]’s cat-sized quadruped robot designs (link is in Korean, Google translation here) is how slim and sleek the legs are. That’s because unlike most legged robots, the limbs themselves don’t contain any motors. Instead, the motors are in the main body, with one driving a half-circle pulley while another moves the limb as a whole. Power is transferred by a cable acting as a tendon and is offset by spring tension in the joints. The result is light, slim legs that lift and move in a remarkable gait.

[Bijuo] credits the Cheetah_Cub project as their original inspiration, and names their own variation Mini Serval, on account of the ears and in keeping with the feline nomenclature. Embedded below are two videos, the first showing leg and gait detail, and the second demonstrating the robot in motion.

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3D Printed Radius Gauge, Just Add Calipers (And A Wee Bit Of Math)

September 9, 2018 by Donald Papp 16 Comments

With 3D printed arms of fixed measurements, the depth reading from a set of digital calipers can be used to calculate the radius of a curve.

Specialized tools that focus on one particular job tend to get distilled right down to their essentials and turned in an economical consumer product. One example of this is radius (or fillet) gauges: a set of curves in different sizes that one uses to measure the radius of a curved surface by trial and error. To some, such products represent solved problems. Others see opportunities for a fresh perspective, like this caliper-enabled 3D printed radius gauge by [Arne Bergkvist].

[Arne]’s 3D printed radius gauge is a simple object; a rigid attachment for a nearly ubiquitous model of digital caliper. By placing the curve to be measured between the two arms of the device and using the depth measurement of the caliper to measure distance to the curve’s surface, a simple calculation (helpfully printed on the unit itself) of radius = distance * 2.414 reveals the radius of the curve. However, this shortened calculation makes a number of assumptions and only works for [Arne]’s specific design.

Another version by [Fredrik Welander] represents a more flexible take on the same concept. His RadGauge design (pictured up top) has a few different sizes to accommodate a variety of objects, and his Git repository provides a calculator tool as well as some tips on fine tuning to allow for variations in the dimensions of the printed attachment.

3D printing has opened a lot of doors, and items like this show that the plastic doodads created aren’t always the end result in and of themselves; sometimes they are the glue that enables a tool or part to work in a different way. To help get the most out of 3D printing, check out the in-depth coverage of how to best tap 3D printed parts for fasteners, and [Roger Cheng]’s guide to using 3D printed brackets and aluminum extrusion to make just about anything.