Self-Playing Kalimba V2 Thanks To Readers Like You

February 25, 2020 by Kristina Panos 12 Comments

Would you like to know the great thing about this community we have here? All the spitballing that goes on every day in the comments, the IO chat rooms, and in the discussion threads of thousands of projects. One of our favorite things about the Hackaday universe is that we help each other out, and because of that, our collective curiosity pushes so many designs forward.

[Gurpreet] knows what we’re talking about. He’s back with version two of his self-playing kalimba, driven as strongly as ever by the dulcet tones of the Avatar theme. Now the robo-kalimba is rocking two full octaves, and thanks to your comments and suggestions, has relocated the servos where they can’t be picked up by the soundboard.

We gasped when we saw the new mechanism — a total of 15 rack and pinion linear actuators that make the kalimba look like a tiny mechanical pipe organ. Now the servos float, fixed into a three-part frame that straddles the sound box. [Gurpreet] melted servo horns to down to their hubs rather than trying to print something that fits the servos’ sockets.

Thumb your way past the break to check out the build video. [Gurpreet] doesn’t shy away from showing what went wrong and how he fixed it, or from sharing the 3D printering sanity checks along the way that kept him going.

Plucking kalimba tines is a difficult problem to solve because they’re stiff, but with timbre sensitive to many degrees of pressure. A slightly easier alternative? Make a toy player piano.

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A Word Clock, The Hard Way

April 2, 2019 by Dan Maloney 19 Comments

We’ve all seen word clocks, and they’re great, but there are only so many ways to show the time in words. This word clock with 114 servos is the hard way to do it.

We’re not sure what [Moritz v. Sivers] was aiming for with this projection clock, but he certainly got it right. The basic idea is to project the characters needed to compose the time messages onto a translucent PVC screen, which could certainly have been accomplished with just a simple character mask and some LEDs. But for extra effect, [Moritz] mounted each character to a letterbox mounted over a Neopixel. The letterboxes are attached to a rack and pinion driven by a micro servo. The closer they get to the screen, the sharper the focus and the smaller the size of the character. Add in a little color changing and the time appears to float out from a jumbled, unfocused background. It’s quite eye-catching, and worth the 200+ hours of printing time it took to make all the parts. Complete build instructions are available, and a demo video is after the break.

We like pretty much any word clock – big, small, or even widescreen. This one really pushes all our buttons, though.

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Save A Few Steps On Your Next Build With These Easy Linear Actuators

November 2, 2018 by Dan Maloney 18 Comments

A lot of projects require linear motion, but not all of them require high-accuracy linear slides and expensive ball screws. When just a little shove for a door or the ability to pop something up out of an enclosure is all you need, finding just the right actuator can be a chore.

Unless someone has done the work for you, of course. That’s what [Ali] from PotentPrintables did with these 3D-printed linear actuators. It’s a simple rack-and-pinion design that’s suitable for light loads and comes in two sizes, supporting both the 9-g micro servos and the larger, more powerful version. Each design has a pinion that has to be glued to a servo horn, and a selection of rack lengths to suit your needs. The printed parts are nothing fancy, but seem to have material in the right places to bear the loads these actuators will encounter. [Ali] has included parts lists and build instructions in with the STL files, as well as sample Arduino code to get you started. The video below shows the actuators in action.

We’re heartened to learn that [Ali] was at least partly inspired to undertake this design by a previous Hackaday post. And we’re glad he decided to share his version; it might save us a few steps on our next build.

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Popup Notification Dinosaur

October 18, 2018 by Bryan Cockfield 1 Comment

There’s a lot going on our virtual spaces, and anyone with a smart phone can attest to this fact. There are pop-up notifications for everything you can imagine, and sometimes it’s possible for the one really important notification to get lost in a sea of minutiae. To really make sure you don’t miss that one important notification, you can offload that task to your own personal dinosaur.

The 3D-printed dinosaur has a rack-and-pinion gear set that allows it to extend upwards when commanded. It also has a set of LEDs for eyes that turn on when it pops up. The two servos and LEDs are controlled by a small Arduino in the base of the dinosaur. This Arduino can be programmed to activate the dinosaur whenver you like, for an email from a specific person, a reply to a comment on Reddit, or an incoming phone call to name a few examples. Be sure to check out the video below the break.

With this dinosaur on your desk, it’s not likely you’ll miss its activation. If you’d like something that has the same function but with less movement and more lights, there’s also a notification 3D cube made out of LEDs that’s sure to catch your eye as well. Continue reading “Popup Notification Dinosaur” →

Linear Clock Slows The Fugit Of The Tempus

April 1, 2017 by Dan Maloney 11 Comments

We feature a lot of clocks here on Hackaday, and lately most of them seem to be Nixie clocks. Not that there’s anything wrong with that, but every once in a while it’s nice to see something different. And this electromechanical rack and pinion clock is certainly different.

[JON-A-TRON] calls his clock a “perpetual clock,” perhaps in a nod to perpetual calendars. But in our opinion, all clocks are perpetual, so we’ll stick with “linear clock.” Whatever you call it, it’s pretty neat. The hour and minute indicators are laser cut and engraved plywood, each riding on a rack and pinion. Two steppers advance each rack incrementally, so the resolution of the clock is five minutes. [JON-A-TRON] hints that this was a design decision, in part to slow the perceived pace of time, an idea we can get behind. But as a practical matter, it greatly simplified the gear train; it would have taken a horologist like [Chris] at ClickSpring to figure out how to gear this with only one prime mover.

In the end, we really like the look of this clock, and the selection of materials adds to the aesthetic. And if you’re going to do a Nixie clock build, do us a favor and at least make it levitate.

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Full-Auto Crossbow Rocks And Rolls On Rubber Bands And Electric Drill

January 11, 2017 by Dan Maloney 26 Comments

You’ve got to enjoy any project where the hacker clearly loves what he or she is doing. And when the project is as cool as a motor-driven, rubber band powered, fully automatic crossbow, it’s hard not to laugh along.

A full-auto crossbow is no mean feat, and it took a man with a love for rubber-powered firearms to get it right. [JoergSprave]’s design is based on a rack-and-pinion system and executed mainly in plywood. The main pinion gear is a composite of aluminum and wood, in a bid to increase the life of the mechanism and to properly deal with the forces involved. The pinion, turned by a powerful electric drill, drives the rack back and locks the carrier under the 30-bolt magazine. A rubber-powered follower forces a bolt down and a cam on the pinion trips the sear, the bolt is fired and the cycle continues.

We slowed the video down a bit and it looked to us like the cyclical rate of fire was about 7 rounds per second, or a respectable 420 rounds per minute. Pretty powerful, too, and the accuracy isn’t bad either.

We’ve seen [Joerg]’s inventions before, like this soda bottle Gatling arrow launcher, or his ridiculous machete launcher. We hope he keeps having fun and letting us watch.

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DIY Mini Printer Is 95% Wood, Prints Tiny Cute Images

December 12, 2016 by Donald Papp 6 Comments

This little DIY 64×64 graphical printer by [Egor] is part pen plotter in design, somewhat dot matrix-ish in operation, and cleverly designed to use unmodified 9G servos. The project page is all in Russian (translation to English here) but has plenty of photos that make the operation and design clear. Although nearly the entire thing is made from laser-cut wood, [Egor] says that a laser cutter is optional equipment. The first version was entirely cut with hand tools.

Small DIY CNC machines driven over a serial line commonly use Arduinos and CD-ROM drive guts (like this Foam Cutter or this Laser Paper Cutter) but this build uses its own custom rack-and-pinion system, and has some great little added details like the spring-loaded clip to hold paper onto the print pad.

The frame and parts (including all gears) are laser-cut from 4 mm plywood and the unit is driven by three small servos. A simple Java program processes images and an Arduino UNO handles the low-level control. A video of everything in action is embedded below.
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