The Rube Goldberg Machine
26th February
Introduction
This blog will document the design and construction of the Rube Goldberg Machine. As mentioned in my introduction blog, I’ve been tasked with constructing a Rube Goldberg Machine where the robot plays a starring role.
A Rube Goldberg Machine is a chain reaction-type machine or contraption intentionally designed to perform a simple task in an indirect and overly complicated way. Here’s a fantastic example: Page Turner. It takes 2 minutes and multiple unnecessary processes to simply turn a page.
I drew up some draft flow diagrams to help illustrate this concept with a bit more clarity.
You can visualize how every normal engineering process works with as few processes as possible to maximise efficiency. Check the Rube Goldberg Flow Diagram Example below
It’s chaos. You might think it pointless, involving many redundant exercises. Nevertheless, trying to think of entertaining, stimulating designs that force you to think outside the box is remarkable for encouraging ingenuity, a skill that every engineer needs.
Materials
In terms of materials and components I’ll use for this project, I’m constrained to items I have around this house. I produced a modest and simple word cloud below where I vomited as many relevant household components I had onto a page.
It’s a bit rudimentary, I'll admit, but it’s an admirable starting point to try to get the creative juices flowing. I’m going to try to gather materials over the next few days.
Design Concept
Above is my initial design concept outlining primary requirements, functions, concerns and initial thoughts on how to execute them. I’ll update it as I go along. I also need to figure out what my end goal will be in the Rube Goldberg. What will the final output be?
27th February
Spent most of the day searching for components.
Lego. A better investment than gold, according to the Russian School of Economics. A staple of any household. I’ll plan to use this for holding a lot of the aspects of the Rube Goldberg machine together. I’ve also a classic design of a pulley system below.
Component 1: Pulley and Projectile System
1st March 2021
An unfixed, free-wheel stolen from my brother’s gym equipment, and polypropylene combined with 4 2oz fishing weights, gives me my pulley system. I might adjust the weighting in the future to give a slower falling speed. I’ll assemble some sort of rudimentary housing component tomorrow to hold it at a height and find some way to fix the lighter weight onto a latch.
It is fantastic to finally build something concrete for the Rube Goldberg and a Pulley System is a crucial engineering application to incorporate. I can worry about adding flair and entertaining aspects closer to the time.
2nd March 2021
Above is an initial design for my housing component for the pulley. I’d initially planned to have 4 separate pillars, and they converged like arches at the top. However, due to structural issues and forces to be balanced, I had to add in a centre piece linking them. Mechanical issues like these are only found from trial and error in practical work, so it's beneficial that I figured it out sooner rather than later. As evident from above, I’m limited to what Lego pieces I have in the house, so symmetry isn’t phenomenal. Although, I kinda like the rough aestheticism it gives off.
It holds it pretty well. There’s substantial stability to it. I might take one weight off because it falls down quickly once released. The handy thing about the fishing weight clasp is that it allows for such ease when adjusting weights.
Here’s how I held the weight in equilibrium. I fashioned a crude notch on the Lego piece on the right, and this allows the fishing part to hook underneath. Any small force that hits the weight perpendicularly will cause the weight to move upwards.
To finish this aspect of the Rube Goldberg I added these two inputs and outputs to the pulley system. The Newton ball acts as a physical input to free the latch, and the Lego Projectile will act as an output, firing its dart into the unknown and into the next aspect of my Rube Goldberg machine. The angle I’m using for the projectile is around 45 degrees currently, but I’ll adjust that as we go on.
Component 2: Sensor system
3rd April 2021
I’m back to working on the Rube Goldberg after focusing a lot on the Robot and CAD. In the meantime, I had been doing much thinking about various components to use for the Rube Goldberg. For the next component, I’m planning to incorporate my own Elegoo kit I have at home.
I’m going to build a electric circuit that incorporates a sensor and then rotates a servo motor 90 degrees. To check my circuit will work and to efficiently troubleshoot the code, I drew up a quick circuit with code on TinkerCAD. It’s an online artificial electronic and coding software.
I spotted no immediate problems, so I was clear to start building my circuit. In fairness, it looks a lot cleaner on Tinkercad than in real life.
It worked! Whenever an obstacle goes within 6 cm of the ultrasonic sensor, it causes the motor to rotate 90 degrees. I then constructed a housing component for this piece.
The plan is to have an obstacle trigger the sensor, causing the Lego piece attached to the servo motor to rotate.
**Update: I couldn’t resist adding LEDs to the device.
Return to The Rube Goldberg
25th April
Right, after a horrendous amount of assignments and multiple class tests, I’m finally back flat out on the Rube Goldberg. I’d been casually tinkering away and thinking of various components for the last two months, so I know exactly what my plan is. Here are the 10 main components below;
These are the main components I’ll be using. Here is a flow diagram of exactly what will happen:
Final Output is going to be…………To activate a coffee machine!
Yeah. This is the plan for the final output. Ironic, because we did a Hackathon on coffee pod machines earlier in the year. The plan is to construct a complex way of activating this machine. This will consist of the components listed in Figure 14. Anyway, let’s get cracking on the components.
Component 1: The Ping Pong Launcher
Well, it would’ve been pointless to not include the launcher. I spent a considerable amount of time on it. I won’t spend long explaining this component since I’ve written an ENTIRE blog post on it here.
The working principles of the Launcher are well documented in the blog, so I won’t go into much detail. This time I’ve swapped the ping pong for a golf ball and removed the other two launchers. This increased mass will help it exert more force. We’ll need this force for the next few components.
The Launcher is raised 30.5 cm at the back. This provides it with an angle of about 55 degrees. The potential energy exerted is sufficient to launch the golf ball. This component will transport the golf ball into Pipe Network 1.
Component 2: Pipe Network 1
This component acts as a method to transport the golf ball from the PPL to the next component. Using PVC pipes from broken posts, it allows me to change the direction of the golf ball. Fig 17.
There wasn’t much engineering complexity to this design. Here were the parameters:
Length of thin tube (52 mm radius)— 70 cm
Length of Thick tube (71 mm radius) — 80 cm
Angle of blue connector — 90 degrees
These were easily connected, since this was their intended design. The thinner pipe was connected to the PPL (Ping Pong Launcher) and the thicker one was the output pipe. This was done to allow the golf ball to fit through, e.g. going from small pipe to larger one.
I ended up adding more books to increase the decline angle, this would:
- Help the ball turn right at the pipe due to gravity
- Increase the speed, and in turn the force of the golf ball going to component
The golf ball is now ready to travel to component 3, The Lever.
** The decline angle ended up being about 45 degrees, as I added more books.
Component 3: The Lever
Right, so you might remember my housing component for a Pulley system that I did a month ago. I’ve decided to scrap that entire and improve on it since I have a much better design for it. The Lego housing component was just a bit too fragile, so I’ve decided to break out the drill once again. Instead of going for a pulley system, I’ve decided to fashion a lever
I drilled holes 15 cm apart on a plank, and then attached two 24 cm tall wooden dowels. At ~22 cm up I drilled two holes to allow a small skewer to fit through to act as a fulcrum for the lever, allowing it to swivel. The actually lever itself is here:
I added more weight to one of the sides, and then hooked the lighter side down with a small Lego construction (The Latch). This will unhook when the golf ball hits it.
This Lever operates off the law of coplanar forces. Each side must balance for it to be in equilibrium. Once the latch is removed, the forces are no longer equal, causing the lever to turn.
This lever will hit Component 4, The Tension Component.
Component 4: Tension Component
This next component's purpose is to activate the ServoMotor/ Ultrasonic Sensor Component 6:
This following component's purpose is to activate the ServoMotor/ Ultrasonic Sensor Component 6: It’s an uncomplicated concept. I built a small stand for the wooden plank (42 cm in height) to rest against. When a force is applied to the top of the plank, it will fall over.
Principle of the Lever
This component operates off this principle, the greater the distance from the fulcrum, the less force required to move it. That is why the previous component hits it so high up the plank ~ 35 cm.
To make sure the component didn’t smash into the floor every time it fell, I attached a 50 cm rope that stopped the plank once it was about ~20 degrees off the ground. I also added 3.75 kg worth of weights to stop the entire stand from falling over.
The above 10 cm x 10 cm blue panel is for activating the next component. It’s relatively large surface area allows it to consistently activate the sensor.
Component 5 & 6: The Servo Motor House and Projectile
I’ve already discussed this component previously. It’s probably my most technical component, so be sure to scroll back to the top of the blog for the details (Figure 12). I assembled an Arduino circuit that operates off an ultrasonic sensor. When the sensor is activated, the LED blinks 3 times, then the servo motor turns 150 degrees.
Instead of moving a small Lego piece, it'll activate the small Lego projectile (Component 6) I used in my pulley system previously. This shoots a tiny projectile out at an angle which I will use to activate Component 7. It’s much easier to show you than explain, so here’s a brief video. My hand is substituting for the blue panel.
Component 7: Pipe Network 2
A fairly simple component, but it serves an important purpose. I have recycled my 2 Launchers that I removed earlier, and connected them as a 24 cm pipe. The plan is for a ping pong ball to be hit by the Component 7 projectile, and go through the pipe and activate the Elegoo robot.
Component 8: The Elegoo Robot
One of the criteria for this assignment was that the robot must play a ‘starring role in the machine, so it makes sense it would come into play at the cliff hanging part of our machine. Having spent hours coding this robot, I could quickly write an Arduino script that caused the robot to turn right when activated, and then go forward. I’ve explained exactly how this code works in other blogs, so here’s the brief void loop() aspect:
Basically, if the ping pong ball is within 20 cm of the sensor, it'll turn right ~70 degrees and go forward on towards Component 9. The Elegoo is crucial to the Rube Goldberg, because it's probably the strongest component I have, and the most flexible in terms of the ability of programming where it should go. I’ve kept the stabilising attachment previously designed. I’ve also attached a 20 cm long piece of wood to the Elegoo, the reason for this will become obvious in Component 9.
The above video shows the ball being fed through the pipe and activating the robot.
Component 9: Bicylce and Golf Club Component
One of the problems I had been concerned with for ages was the ability to activate the coffee machine. It requires a moderate force, but it must be accurate. I’d thought of dozens of ways to design it, but I was afraid I’d break the machine. I finally managed to solve it using angular acceleration.
I got out an old bike wheel and trainer. This gave me a good range of circular motion to spin around. Then many cable ties and rolls of duct tape later, I could add a golf club. This was a ~ 88 cm long heavy piece of metal that would exert adequate force onto the machine. To increase precision, I attached a tiny Allen Key to the Golf Putter. Decreasing the surface area meant greater pressure went onto the coffee machine.
A small skewer was then added to raise the club 2 cm up. This displacement was arrived at by trial and error. The plan is for the Elegoo to knock down the skewer with the wooden piece. This force is then adequate enough to activate the coffee machine.
Component 10: The Coffee MachineVideo
The final component. We’re ready to go.
Honorable Mentions of Components:
There were two components that I didn’t manage to incorporate into the Rube Goldberg. This was more due to insufficient time and *cough cough safety concerns. Here they were
Honorable Component: The Pneumatic Car
The plan was to fire the projectile into this car, which would have a balloon inside.
Honorable Component: The Pellet Gun
An initial plan was to incorporate this into the Rube Goldberg somehow, but the concept never came to fruition.
Conclusion
Well, that’s all the components explained. I was pretty constrained by the sitting room and its insufficient space, but I think I managed it pretty well. As I mentioned before, I wanted to focus on manufacturing legitimate engineering-based components, rather than trivial parts like dominoes etc.
I achieved my goal of carrying out a really simple function in a very complicated way. I fire the Ping Pong launcher and a minute later, I’ve a hot coffee!
Final Video
The End?
Well, this is my final blog post for Engineering Design. I hope you enjoyed reading it. It was a peculiar set of assignments that helped break up the usual mundane aspects of college work. Given the research/theoretical lead approach my college takes towards a lot of the degrees, it was nice to do something practical that really forced me to start thinking. Bye
