Rube Golberg Machine
My final design assignment of the academic year requires me to design and make a Rude Golberg/reaction chain system.
I approached this assignment by first listing the items I had available in my home that I could somehow use in my machine. After rooting about all the cupboards and spaces in my house I had to sit and think of how to make original and exciting steps for the chain.
I began by designing individual stations that I would connect using a domino like system constructed using CD and DVD cases. I wanted each station to show a different mechanism whilst being able to receive power from the previous station and supply the next one in the chain. To get a few ideas I watched many video clips on youtube, some very advanced and others made using only jenga pieces, before I started building my components.
Station 1.
At my first station I wanted to use the height of a radiator to show a level change in my video and add some variety. I placed CD dominos on the top ledge of the radiator cover and a tennis ball at its edge. To tap my first CD case, I placed a golf putter very closely to the first CD. The reaction would start with me tapping the grip of the putter but I then thought this would be an easy place to implement my elegoo robot that I have used in my previous assignments. From the ledge of the radiator, the tennis ball would bounce onto a metal frame which directed the ball towards another set of CD dominos
I really liked the look of this station and the variation added by the level change. However the bouncing aspect was very unreliable, only 1 out of 10 attempts would the ball reach the next CD set. In the redesigning of my station I again used my elegoo robot to initiate the process, but now I placed the tennis ball in the bowl attachment on the elegoo’s top plate. To release the tennis ball I used a ‘function’ of my modified elegoo. I noticed during my last assignment that if my robot drove into a wall or object it would tip backwards. I used this as my initial tennis balls release mechanism by placing a heavy box in front of the robot. After I activated the robot, it would move forward until it reached the box and fell backwards, dropping the tennis ball and projecting it in the direction of the CD dominos.
This new design was much more successful than the previous. As long as the CD cases were positioned correctly, power was supplied to the next station with ease.
Station 2.
The main component of station 2 included two ring binder folders that are closed in different ways to accelerate a golf ball and activate another domino chain. Station 2 receives energy from the CD dominos at the end of station one, the last CD case falls on the corner of a folder which isn't closed properly leaving the top level flat. Using a cardboard tube that I cut in half, I made a channel to run along the level of the folder and direct a tennis ball that would be released when the folder is closed. Once released, this tennis ball would travel along the ground before dislodging a tooth pick that is propping open the second folder. Similarly, this folder also has a cardboard channel that holds a golf ball. When the folder is closed, the golf ball is released and activates the next domino set by tapping an upright deck of cards.
This station did not have many issues and was also easy to reset. The only problem I encountered was that the tennis ball would sometimes become lodged in the second folder, stopping the golf ball from being released. To stop this I shortened the toothpick so that the tennis balls diameter was now larger than the gap of the open folder. I also started the next domino chain with a deck of cards due to their lower centre of gravity compared to the CD case. I required this lower centre of gravity due to the golf balls smaller size, the CD case would often fall backwards on top of the golf ball.
Station 3.
My main idea for the design of this station was to have ball follow a path that required a missing piece to reach the next station. Using a cardboard shoe box and tooth picks, I angle the lid of the box to create a slope for a golf ball to roll down and hit a Guinness ping pong ball from my last assignment into a shot glass. Without the ping pong ball my golf ball would get stuck in the shot glass, however the diameter on the ping pong ball is sufficient to allow the golf ball to roll over the shot glass and hit a cup placed on its side. To reach the elevated height of the golf ball, my dominos grew in size as I progressed from CD’s to books in increasing sizes.
This station worked well, the biggest problem was the speed at which the golf ball was struck at. I altered this by moving the last book closer to the ball and moving the ball as far back on the tube that I could.
Station 4.
The idea for this station was to build a force great enough to offset the next step. In station 3 a golf ball hits a plastic cup placed on its side which then rotates in an angled direction towards a CD case. To build the required energy I increased the size of the dominos using a DVD case, a small book and then a large hard back school book. Attached to the large school book was a long piece of string measured specifically to reach the next station. Using a screwdriver I cut a small hole in the books hard cover and threaded the piece of string through and tied in some knots. Attached to the other end is a small piece of cardboard that lodges into the next station.
Station 5.
For this station I wanted to use a tipping mechanism. Using a fidget spinner and the two hoover attachments from my launcher I created a pivot with openings on both ends. The idea then came to me that I could put an object into the openings, causing the pivot top tip backwards and raise the other hoover extension.
Due to the narrow opening on the hoover extension I couldn't use golf balls as my weight. I rummaged through my room and found a magnets set that included lots of ball bearings, small and dense which was perfect. Next I needed a mechanism to release the ball bearings into the pivot. Using cardboard and tape I made a supply chamber and pathway for the ball bearings to follow. Using the small cardboard piece attached to the string from my previous station, I lodged it tightly between the supply and pathway. When the previous station is completed the large book falls with enough force to remove the cardboard lodge and release the ball bearings.
Once activated, the ball bearings are released and enter the upright hoover extension. The weight of three ball bearings is sufficient to force the clockwise movement of the pivot, resulting in the upward movement of the second hoover extension. Supporting the pivot is two books either side of the fidget spinner as well as another smaller book supporting the horizontal extension. This small book maintains the pivots fixed position but also when the pivot is activated, the small book falls forward and activates the final station.
Station 6
A big decision during the whole process was the question of how to end such a chain of events. I thought with a bang. I blew up a leftover balloon from my launcher and placed small pieces of coloured cardboard inside it as confetti. The aim of the ending was to pop the balloon and label the video as a confetti machine. Continuing from the previous stations I built lots of power through increasing book sizes in a domino chain, the final book being a large atlas. This final book would fall and slide across the tiles where it would push a small toy truck with a safety pin attached. The safety pin would then pop the confetti balloon.
The final video of all stations operating correctly and smoothly took many many many attempts as I altered and tweaked components as I went along to improve my probability of a perfect run. Eventually all came together after constant testing single stations repeatedly and the constant realigning of dominos to produce this great event!
