Rube Goldburg

Filled under: Projects

Date posted: February 2, 2014

Our Applied Engineering Club’s adviser, Dr. Hammond, requested that we, the Applied Engineering Club (AEC) fabricate a Rube Goldburg style machine for demonstrating engineering department talent at various college events. As the acting club president, I took action and identified the goals and options for our machine. We wanted the machine to be portable so we can set it up in the quad or even at local schools for STEM learning days. The machine is best that it is capable of running continuously without the need of constant resetting.

We stumbled upon a neat video of the Great Lego Ball Contraption consisting of a dozen plus stations that transports Lego balls in unique and interesting fashions. This concept fits perfectly into our vision. Each station can have it’s own creator(s) and be easily integrated into the whole machine. Instead of Legos and Lego balls, we decided to build our stations out of readily available materials and 3/4″ glass marbles.

As a club we voted on the direction of the project and budget. From there I presented our proposal to the Student Government Associationand received approval and funding shortly thereafter!

To kick-start the project I fabricated my own station: Music Station.


The station receives marbles on the lower left accumulator which is the entrance to the pump. The pump then lifts the marbles to a point where they drop on the top ramp.

The wood frame components were cut using our college’s laser engraver.


The marble pump is driven by a continuous RC servo and relies on a 1:3 gear ratio to increase the lifting power of the internal rotating mechanism.


The marbles travel down the topmost ramp until they meet the marble release mechanism.

The first hole on the ramp the marbles pass over due to their velocity, but if there is a backup of marbles the accumulated marbles fall through the hole bypassing the drop mechanism.


The  release mechanism allows only one marble to fall through the hole leading to the xylophone plates while holding back the remaining marbles.


The note which is being played is indicated by the LED indication panel. As you can see, the key is C major.


The xylophone plates are rotated into precise position by a RC servo. The gear reduction allows the 90 degree servo to rotate the drum a full 360 degrees.


The melody played is selected by three large illuminated arcade buttons. Melody A is Beethoven’s 9th, melody B is Twinkle Twinkle Little Star, and melody Random is random notes.


The rear of the station shows wiring and the 12vDC power jack. A project goal is safety, so we limited the voltage on all stations to 12V.


At the marble exit of the machine there is a simple switch that counts the marbles so the marble per minute (MPM) can be displayed to add a little bit of sparkle to the machine.


The control system is left open so observers may peer inside to see the machine’s electronic guts. The control system consists of two Arduino Nanos. One as the speed controller and MPM LED display driver, and the other as the melody control system. The picture here shows the electronic panel without the LED display installed.


The station before mine in the loop is Breanna’s rollar coaster station, The Coltnonator. Ignore the ping pong balls, they tend to get into everything.


Here are the two stations connected by proximity.

Hopefully during winter break when I go back home I can make a video of the station in action.