Maker ‘pashiran’ purchased a music box which could be programmed with punch cards, but soon found that actually creating tunes this way by hand was exhausting. His solution was to automate the process, designing a fixture to punch the cards for him!

His new auto-programmer acts as a simple CNC machine, using stepper motors to roll cards into place and then move the punch head perpendicular to this motion to produce the correct note. The holes are punched out over and over with a DC motor, before being removed to play a beautiful tune on the mechanical music box. Computing power is provided by an Arduino Mega, while the user interface consists of an LCD display and an encoder. 

You can listen to the paper-punching project perform 250 notes from “Be Our Guest” below, plus find more details on how it was made here.

Most projects have one or two significant aspects in which custom work or clever execution is showcased, but this Music Box Hole Punching Machine by [Josh Sheldon] and his roommate [Matt] is a delight on many levels. Not only was custom hardware made to automate punching holes in long spools of paper for feeding through a music box, but a software front end to process MIDI files means that in a way, this project is really a MIDI-to-hand-cranked-music-box converter. What a time to be alive.

The hole punch is an entirely custom-made assembly, and as [Josh] observes, making a reliable hole punch turns out to be extremely challenging. Plenty of trial and error was involved, and the project’s documentation as well as an overview video go into plenty of detail. Don’t miss the music box version of “Still Alive”, either. Both are embedded below.

As [Josh] mentioned on his project page, he was inspired by a tutorial video showing how to punch music by hand. It led to this tool to take a MIDI file and cut the music paper out on a laser cutter, whereas [Josh] and [Matt] were inspired to automate the entire process in their own way.

For those of you who don’t think science should stop there, why not automate the creation of the music itself with the output of this Bach-emulating Recurring Neural Network?

Thanks to [Tim Trzepacz] for giving us a heads up on this delightful project!

[Bokononestly] found a lil’ music box that plays Stairway to Heaven and decided those were just the kinds of dulcet tones he’d like to wake up to every morning. To each his own; I once woke up to Blind Melon’s “No Rain” every day for about six months. [Bokononestly] is still in the middle of this alarm clock project right now. One day soon, it will use a *duino to keep track of the music box’s revolutions and limit the alarm sound to one cycle of the melody.

[Bokononestly] decided to drive the crank of the music box with a geared DC motor from an electric screwdriver. After making some nice engineering drawings of the dimensions of both and mocking them up in CAD, he designed and printed a base plate to mount them on. A pair of custom pulleys mounted to the motor shaft and the crank arm transfer motion using the exact right rubber band for the job. You can’t discount the need for a hig bag ‘o rubber bands.
In order to count the revolutions, he put a wire in the path of the metal music box crank and used the body of the box as a switch. Check out the build video after the break and watch him prove it with the continuity function of a multimeter. A clever function that should at some point be substituted out for a leaf switch.

We’ve covered a lot of cool clock builds over the years, including one or two that run Linux. And say what you will about Stairway; it’s better than waking up to repeated slaps in the face.

[via r/engineering]