ENGR 101: Rube Goldberg Module Final Report - Lab Section 74, Group 7

Group Members:

Jon Ferro

D Yoan L Mekontchou Yomba

Chris Lor 

Machine Overview

 

Figure 1. Final flattened 2D view of the final Rube Goldberg machine  

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    Input: 3”, 2”, 8”                                                                         Output: 32”, 3.5”, 2.5”:  

 

Figure 2. Final top­down detailed floor plan of the machine  

Table 1. Machine Operating Script 

Event #  Event Description 

1  Water from group 6 drops into a cup which is on a lever. The water causes the                                 lever to tip and hit the two balls at the top of the ramp above the lever. 

2  The two balls roll down the ramp. One ball falls into a hole in the ramp and the                                   other roll across it. The ball triggers a set of dominoes.  

3  The dominoes trigger a mousetrap which starts event 4 by pulling out a card                           that holds a golf ball in place.  

4  The golf ball rolls down a ramp and knocks over a cup of water. The water flows                                 down a ramp to event 5. 

5  Water from event 4 pours into a cup on a pulley. The cup slides down and lifts                                 the cup on the other side up. 

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The cup from event  tilts a platform, causing a ball bearing to travel from the platform to a lever. The lever tips, releasing a golf ball and allowing the ball bearing to travel to another ramp. The golf ball travels down a ramp as the ball bearing travels down the other ramp. The golf ball hits a wall with a thumbtack attached which pops a balloon obstructing the ball bearing’s path, allowing the ball bearing to continue. 

7  The ball bearing hits a set of dominoes that ascend up a staircase and knocks a sugar cube into a cup.  

 

   

Figure 3. 3D model of the final machine. 

Event Design Details

Event 1 (Input Event)

After testing the initial design, it was determined that the cup side was too heavy and needed a                                   

counter weight so that the event could work with group 6’s output. The opposite side had a ball                                   

bearing taped to it and was rested on a barrier so that the lever would not tilt one side. 

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Figure 4. Initial Design of Event 1 (Input event).  

 

 

Figure 5. Final Design of Event 1 (Input event).

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Input: Water from group 6 is poured into the cup at 3”, 2”, 8” 

Figure 6. Event 1 3D model (Input event).  

Event 2

The lower end of the ramp was raised so that the top end was tilted low enough for the lever in                                         

event 1 to hit the platform and set the ping pong balls rolling. 

 

 

Figure 7. Initial Design of Event 2  

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Figure 8. Final Design of Event 1  

 

Figure 9. Event 2 3D model 

Event 3

The initial design included cardboard cylinders in the middle of the domino chain, but after                             

testing, they were found to be inconsistent due to water damage on the board, so they were                                 

removed. 

 

 

Figure 10. Initial Design of Event 3  

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Figure 11. Final Design of Event 3  

 

Figure 12. Event 3 3D model 

Event 4

Extended the golf ball ramp to the cup, ensuring that the ball would knock over the cup every                                   

time. The ramp was also raised an inch to give the pulley in event 5 more space. 

Figure 13. Initial Design of Event 4  

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Figure 14. Final Design of Event 4  

 

Figure 15. Event 4 3D model 

Event 5

The entire event was raised an inch and a half in order to provide more space for one side to                                       

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rise so that it started event 6 properly. 

 

Figure 16. Initial Design of Event 5  

 

Figure 17. Final Design of Event 5  

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Figure 18. Event 5 3D model 

Event 6/7 (Output Event)

When testing the initial design, the ball bearing would get stuck on the lever or the track. The                                   

bumpers on the lever were adjusted, and the track was raised so that the incline was large                                 

enough to keep the ball rolling. Also added more “stairs” to allow for a larger cup. 

Figure 19. Initial Design of Event 6/7 

 

 

Figure 20. Final Design of Event 6/7 

 

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Output is a ball bearing knocking over set of dominoes, hitting a sugar cube into the cup. Output at 32”, 3.5”, 2.5” 

Figure 21. Event 6/7 3D model  

Machine Setup and Reset

 

Table 2. Machine Setup 

1  Place two ping pong balls on the platform of the ramp of event 2. Bend the paper however necessary to make both balls remain stationary. 

2  Set up the dominoes in events 3 and 7. 

3  Load the mousetrap in event 3 and set up the card stock and golf ball in event 4. 

4  Fill the cup with water in event 4. 

5  Set up the pulley in event 5 such that the cup connected to event 4 is pulled up as high as possible. 

6  Place a ball bearing on the first platform of event 6. Place the golf ball on its ramp and set up the lever such that the k’nex rod holds the golf ball stationary. 

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7  Blow up a balloon and place it as close to the thumbtack as possible in event 6. 

8  Place the sugar cube at the top of the stairs in event 7. 

 

Average setup time: 3­4 minutes.   

 

Table 3. Machine Reset 

1  Empty water in events 1 and 5. This is most easily done by placing paper towels in the cups to absorb the water. 

2  Place two ping pong balls on the platform of the ramp of event 2. Bend the paper however necessary to make both balls remain stationary. 

3  Set up dominoes in events 3 and 7. 

4  Load the mousetrap in event 3 and set up the card stock and golf ball in event 4. 

5  Fill the cup with water in event 4. 

6  Set up the pulley in event 5 such that the cup connected to event 4 is pulled up as high as possible. 

7  Place a ball bearing on the first platform of event 6. Place the golf ball on its ramp and set up the lever such that the k’nex rod holds the golf ball stationary. 

8  Blow up a balloon and place it as close to the thumbtack as possible in event 6. 

9  Place the sugar cube at the top of the stairs in event 7. 

 

Average reset time: 2.5­4 minutes 

The dominoes originally took the most time to set up and reset so tape was added to each one, 

reducing the time to set them up. Now, soaking up the old water and refilling the cup take the 

most time.   

 

Summary

Initially, this team came together and pondered the final version of the machine. The project                               

constraints were discussed, resulting in the choice of material. The chosen materials were                         

cardboard, plastic wrap, dominoes, tape, k’nex, ping pong balls, and golf balls. At the beginning,                             

the machine was made up completely of levers and pulley systems. It was a complex bundle of                                 

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events that needed to be further sorted and simplified. For example, in event 1, water would be                                 

poured from group 6 to 7, causing a lever to tilt. The lever would hit a platform with 2 balls,                                       

creating a parallel which would loop around the entire machine while the other set of events was                                 

going off. Seeing how this could potentially cause many problems and malfunctions, it was                           

decided that the parallel be removed and placed closer to the end of the machine, which would                                 

aid in getting a more perfect performance. A constraint that made the project a bit more difficult                                 

(though it was a constraint caused by our compacted events) was the height. Because the                             

machine could not be too high due to so many balls and liquids being dropped and spilt in every                                     

other event, the heights had to be chosen carefully and events had to be tested rigorously at all                                   

types of different heights. For example, at the second event, the angle of the ramp had to be                                   

angled at 75 degrees in order to regulate the speed at which the first and second ball rolled. The                                     

height of event number 4 had to be carefully picked and tested. As a result of the mouse trap’s                                     

force and rate at which it pulled off the barrier of event 4, event 4 had to be raised to 14.5 inches                                           

to keep the ball behind the barrier from flying off. Event 5 had to be raise by an inch and a half                                           

to make sure one side of the pulley made contact with the edge of event 6. The circular ramp at                                       

the end of event 6 had to be raised by half an inch to facilitate the ball bearing in traveling                                       

efficiently through the event.  

This machine had to be tested over and over and over again to work out flaws and                                   

malfunctions. Originally, the previous unedited machine rarely got past event 3 without a                         

malfunction of some type. After testing and changing different heights, positions, and angles,                         

the new and improved version of the machine consistently reached the end of the event 6                               

before ever experiencing a malfunction, if any. A deep understanding of angles and velocity                           

aided exponentially in creating every single event. Basic problem solving techniques were used                         

on a daily bases and ideas from other groups equally helped create the finished machine. 

This project brought up many lessons that pertained mainly to the design process. For                             

example, the importance of space in this project changed everything. Every idea brought up had                             

to first be able to fit in the space required if it were to even be considered. Also, the concept of                                         

the constraints (2 special events) brought about many failures which resulted in many lessons                           

learned. For example, the new learned ways to control the flow of water in a tight space and the                                     

different ways to limit or increase speed were examples of lessons taken from the design                             

process. As far as improvements, the transfer from events 5 to 6 (pulley system) could be                               

altered to facilitate energy transfer in order for a more reliable run.  

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