Introduction: Rube Goldberg "Gumball" Machine- With Marbles
Isn’t it so satisfying watching something travel through the twists, spins, and turns of a Rube Goldberg machine- a complex machine in which one action triggers a series of actions? It’s like it’s riding on its own rollercoaster! What if it was a gumball, that dispenses by coursing down a twisting trail at the flick of a switch?
Well, that is exactly what we did here. How did we come up with this you may ask? We combined different ideas to create this wonderful piece.
Have you ever seen those gumball machines at the mall and wondered how does that gumball get down from the top to the dispenser in the bottom? How it could be automated? Well one idea that we had was that putting together two discs, with a hole to let the gumball fall through in both, placed on top of each other, could be dispensed at a certain rate if a gumball fell when it lined up! It’s like the tops of a salt container, where you rotate the openings to meet up when you need salt.
Although most gumball machines have a spiral track, we saw one of those machines and just knew that we could add an interesting piece of art where the track goes. A Rube Goldberg mechanism as a gumball dispenser would be so fascinating and satisfying to watch. It acts like a piece of art, bringing the wow into an ordinary machine.
Just like museums have precious artifacts under glass, so people could admire the piece beneath, we thought we should do something like that, so users can see what is going on with the traveling gumball, and it protects the mechanism.
We made our beautiful Gumball-Rube Goldberg Machine using ideas from an actual gumball dispenser and added our own creativity to it.
This is more of a process or prototype-in-the-making, so you will need to tweak the project in order to complete it.
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Step 1: Materials and Tools
- LEDs Acrylic
- 4 isocolese trapezoids Height: 10 in Width: 5.75 in Width: 7.75 in Side length: 11 in
- Wood Width: 9.5 in Height: 9.5 in
- Topper 3-D printed Diameter: 4 in
*Create your own design to fit in top opening 1 DC motor 1 jar For our design, we used one about 6.5 in * 6 in Preferably plastic with a lid, we used a kimchi jar.
- Pringles container Diameter: 3 in Height: 10 in
- Battery pack(s)
- Batteries Toggle switches (*2)
- Rube Goldberg mechanisms
**You can use a variety of materials Wood 3-D print, screws, straws Pipes Brass Fasteners String Solder Wire Resistors Hot glue
- Exacto Knife
- Exacto Knife Board We used a self healing cutting mat
- 3-D Printer CNC Machine (?)
- Drill Press
- Scroll Saw
- Band Saw
- Hot Glue Gun
- Band Saw Fence
- Band Saw Miter Gauge
Always wash your hands after using solder, it contains lead and can give you lead poisoning
We used marbles instead of a gumballs because we were afraid it may come into contact with the solder, because we didn't wan't anyone to get lead poisoning, and advise you to do the same
Always be careful when using an exacto knife
Make at your own risk
Step 2: Cutting Out the Shape of the Base
It would be best that you had wood that was larger than 9.5x9.5x2 inches, since then all you would have to do was cut it out, but since we didn’t have wood to that dimension in our engineering classroom, it was time to get a little crafty.
If you have wood larger than the dimensions of the wood
Cut the wood to 9.5x9.5x2 inches.
If you do not have wood larger than the dimensions of the wood
- Cut the wood to 4.75x9.75 inches with wood that has a height of 1 inch, so that there is a total of 4 pieces (figure 1).
- Since we did not have wood that was 2 inches, and our wood was about 1 inch in height, we cut 4 pieces of wood out
- We used a band saw to cut our pieces out, along with a fence and a miter gauge, for rip cuts and cross cuts
- BE CAREFUL NOT TO CUT THESE PIECES OUT WRONG, we cut them in the wrong dimensions at first, and it did not work (figure 2)
Place two pieces next to each other, to form a square, and place the other two together, to form another square
Place the two pieces on top of each other, so that when two pieces are horizontal the other two run verticalDrill 4 holes, one near (but not too close to) each corner, so that the holes go through the bottom pieces too, to form a square
Screw into the holes, so that it forms a tight square, measuring 9.5''x9.5''
Step 3: Adding the Battery Pack Hole to the Bottom of the Wood.
- Cut a hole that measures slightly larger than the batteries you are using
According to where you want to place the battery pack, drill the hole in the middle or to the side of the bottom of the wood. We made it in the middle, although a little off center so that the wires would go at the middle. Since we had two layers of wood, we drilled the battery pack hole only in the bottom layer, and created a second hole through to the top, so that wires can go into the pringles can. If you want it to the side, do not create a hole all the way through, if you want it in the middle, make sure your can is larger than the hole you are creating. Get creative to make it suits your needs!
Step 4: Cut Out the ⅛” Acrylic for the Transparent Cover
- Get your acrylic sheets ready
- Do not take off the blue film yet
- Cut your acrylic into 4 isosceles trapezoids using an acrylic cutting knife*
- To cut the acrylic take a ruler (metal) as a guide of where you want to cut
- Run the hook of the knife on the acrylic, scoring 2-3 times
- Snap the acrylic against a table
- Our dimensions were:
- Height: 10 inches
- Top Width: 5.75 inches
- Bottom Width:7.75
- Side length: ~11 inches
- We then realized that they should be longer if the height of the can is 10 inches, since it is the hypotenuse of the acrylic, and the acrylic is on a slant, but we found that it didn't make that big of a difference
- On one of the pieces of the acrylic, cut out a small opening in the middle of the bottom of the acrylic pieces in the shape of a door with an arc on top, in the dimensions 1.5’’ by 2’’ (or slightly larger than your marble)
- Our dimensions were:
On one of the pieces of the acrylic, cut out a small opening in the middle of the bottom of the acrylic pieces in the shape of a door with an arc on top, in the dimensions 1.5’’ by 2’’ (or slightly larger than your gumball)
*be sure to have a mat underneath the cutting knife that you don’t mind being cut up a little
*be sure to be careful when using an exacto knife
Step 5: Gluing the Acrylic Sheets
Glue the sides with hot glue and make a trapezoid prism.
Hot glue dries quickly so attach one by one quickly. Since we cut the top too big, we added a wood square with a circle to help the jar fit better.
Step 6: Create the Rube Goldberg Parts
If you can access a 3-D printer
We used the CAD program on www.onshape.com and www.tinkercad.com. Make an account and play around with the program to figure out how to use it. There are videos and instructions on how to use the program that you can find on the website. Create shapes that you will use in the Rube Goldberg track We used half-tube, tube, levers, and wheel shapes. Although we only printed out a half tube at the end Make sure the dimensions are accurate to your design. Adjust to the size of the ball and the radius of the can and the lid of the jar. Print out these shapes and plan on how to assemble them.
If you do not have a 3-D printer
Use your own materials using your creativity to create pieces that you can use in the Rube Goldberg track, such as wood, popsicle sticks, water bottles, straws, toilet paper rolls, cardboard, e.t.c
Step 7: Cut the Lid of the Jar to Make an Opening for the Gumball
You will need an Exacto knife or another cutting tool to make a hole in the lid. The hole has to be a little larger than the gumball itself, allowing it to flow freely. For the purpose of aesthetics, a circular hole is better, but the shape of the hole will not affect the efficiency of the prototype, so it is up to you.
Step 8: Cut Out the Disc and Drill a Hole
Creating the disc
We found a circular piece of wood that we could use because cutting a circular piece to the right width is difficult, so try to find something that works.
If you could not find anything
Find wood that is the required thickness, the lighter the better. Use the scroll saw to cut the wood into a circle, make sure to use relief cuts. Sand down for smooth edges.
Drilling a hole into the disc
Drill a hole so that when the disc rotates it will match up to the hole on the jar to allow the gumball to fall out. Glue this to the motor. If the attachment is not secure enough, try drilling a hole in the middle of the disc and gluing it into the rotating part of the motor
Step 9: Building the Circuit Online
If using tinkercad.com
Make an account. Create a circuit with the essential parts, including the LEDs, Arduino (if applicable), and motor. Play the simulation to make sure the circuit works before you start making it. We had quite a problem with the circuit, because the Arduino was giving us some trouble, and we could not get it to work unless it was connected to the computer. Later, we found what was wrong: there was some loose connection so we had to connect the wire from the motor to the resistor directly to each other and not into the breadboard. Even with the Arduino, we did not attain the speed we wanted, so we switched to mystery motors which are naturally slower than a normal motor.
Since we had a time limit, we had to move on to a different idea, but if you don’t have a time limit… try try again!
If you are not using tinkercad.com
Maybe draw out a template before you build the circuit on a breadboard so that you have something to look at while building. Starting with the actual circuit could take more time with all the trial and error.
Please look at the captions on our images for details
Step 10: Make the Circuit and Solder
Use a breadboard to lay everything out and test it before you start soldering. While soldering, make sure to test as you go to catch your mistakes because if you accidentally burned the wire, and the connection is lost, you won’t know unless you check.*
- You can use an Arduino to control the speed of the motor, but we could not figure out how that would work out, so we used a very slow motor instead.
We attached the battery connector to a switch on one side, and then to the motor, and then back to the battery connector. Make sure the switch can be placed where you want it.
For the lights, attach the wire to the same battery connector. Connect to a switch. Place lights in parallel, one resistor and one LED, until you have them all connected.
Our breadboard circuit only worked in the simulation, so we used a different motor and ditched the Arduino. We needed the speed of the motor to be about 20rpm, but that was not achievable even with the Arduino.
While soldering, you have to tap the tip of the solder wire with the iron then hold it to the wire connection, and slowing tap the solder wire to the connection as you go. Don’t hold it for too long, which will burn the wire, and if you don’t clean the iron tip often, you will get lumps of solder, which will also break the connection. Additionally, make sure you have enough wire between the parts of your circuit, so you have space to attach it freely.
Step 11: Cutting the Can
Preferably you have a slightly less than 10 inch can, but if you don’t, glue another can on top.
- Cut a small slit at the base of the can so that you can feed the wires through
- Cut another slit near the bottom of the can so that you can feed the wires through for the switch
- We had to cut out parts of the top of the can to let our motor fit, but if you are using an Arduino or regular motor, it is ok
Step 12: Putting Everything Together
- Glue the motor down to the can, making sure that the hole on the disc and the hole on the lid are aligned
- Make sure that the disc can rotate smoothly on the surfaces, and that the disc and the lid are right next to each other
- Feed the wire through the can, and to the bottom
- Glue the battery pack to the battery pack cutout, ensuring that the battery can fit
- Let the lights go through the can first, and poke holes where you want the lights to be, and put them through, possibly gluing the lights down, or just glue them wherever you want to glue them
- Glue the Rube Goldberg parts
- Start the first part of the track by laying the first thing the marble will fall into directly under the hole
- Keep on going to create a path for the marble until it falls into the opening at the end
- Use straws and skewers for the axel for the wheel, and popsicle sticks and small containers for the wheel
- Attach skewers to the can and to the mechanisms to hold them in place
- Make sure that the marble can fall into the hole at the end
Turn it on and see what happens!
Step 13: Troubleshooting
You are going to come into problems along the way, as we did. This may not be reflected in the instructions, of the minor tweaks we had to make that were suited to our design. In fact, we are still working on finishing it. As you make this your own design, and as building this you will have problems along the way, keep on pushing through and trying to adjust the problem until it works. Engineering is all about problem solving.
Step 14: Reflection
We came across a lot of problems while doing our project. but the idea of building a Rube Goldberg mechanism yourself is our favorite part of the project. We also really liked how the 3D printed parts turned out. We wish we could make a bigger structure so we have more space to add to the Rube Goldberg mechanism. We would also change the time limit, so we can make an awesome project to the best of our ability. It took us so much time to explore and figure out what we were doing and the details, that we ran out of building time quickly. When we used the Arduino, it threw off our whole schedule. We did not know how to fix it or use it, because we were new to the whole thing. Before starting your project, we recommend that you do good background research and plan efficiently so you have time to build. Cutting the acrylic was also a bit of a pain, but it was worth it.