Blog Entry 6

Hello! Yes, I am back once again HAHA😄. 

Today, I will be sharing about my experience in Practical 4 which is the Marble Run  and mechanism design of our Ping Pong Ball Launcher 🏓.

LET'S GOOOO!!!!!!!!!!!😎😆

Ping Pong Ball Launcher

Before designing our Ping Pong Ball Launcher, Mr Chua taught us what are some operating principles and engineering mechanism.

Operating Principles

There are many examples in everyday devices around you. For example:

• Steam traps operate on the principle of specific gravity
• Foil shavers work based on reciprocating motion
• Air-lift pump (such as the one inside a coffee maker) works on the principle of buoyancy
• Brewing coffee involves the leaching of coffee solubles
• Centrifugal pumps impart energy to the liquid by means of a centrifugal force developed by the rotation of an impeller

Engineering Mechanism

In order for the identified operating principle to work efficiently, mechanical movements are often required.

In Engineering, mechanism refers to the combination of rigid or resistant bodies, formed and connected so that they move with definite relative motions with respect to one another. 

More simply, it is something that transforms forces and movement into a desired set of output forces and movement.

6 Essential Mechanism in functional prototypes:

1. Actuators
2. Cams
3. Gears
4. Lever
5. Ratchets
6. Springs

Now, I will be explaining more on the Ping Pong Ball Launcher my team and I has come up with.

Propulsion principle

• The toy uses the elastic bands as the energy storage mechanism to propel the ping pong ball.
• The main propulsion principle is stretching the elastic bands causing the bands to have elastic potential energy stored. The elastic potential energy will then be converted to kinetic energy which causes the balls to propel forward.
• The user manually stretches the elastic bands by pulling the trigger located at the bottom left side shown in the picture below.

Ball loading

• For the ping pong balls to be loaded, the elastic band needs to be pulled, to allow the ping pong balls to roll down as shown in the picture below.

• The elastic bands have spring-like characteristics which enable it to store and dissipate energy.
• When the trigger is being pulled back, elastic energy will be stored in the elastic bands.
• When the trigger is released, the elastic band will snap back. Causing the ping pong ball to propel forwards.
• After the ball propels off, the gun needs to be loaded using a piston mechanism. When loaded, it reloads the launcher by pushing the next ping pong ball up. This can be seen in the before and after pictures shown below.

Before reloading:

After reloading:

Ball propelling

• This principle is based on the physics of projectile motion. Projectile motion is the motion of an object thrown or projected in the air, subjected to only the acceleration of gravity.

• With gravity, a “projectile” will fall below its inertial path. Gravity acts downward to cause a downward acceleration. There are no horizontal forces needed to maintain the horizontal motion - consistent with the concept of inertia.

Sketch of our Ping Pong Ball Launcher

Practical 4

The aim for Practical 4 is to come up with a cardboard design that can keep a marble to be in constant motion for 30 seconds.

Before Practical 4 started, my team and I planned to make a cardboard pinball machine using the spring mechanism to push the marble up to ensure it is in constant motion for 30 seconds.

Initiate design (pinball machine):

How this pinball machine works is that there will be 2 flippers that pushes the marble up. To control the flippers, there will be a PUSH button for each flippers. To apply the spring mechanism, rubberbands were used as it is elastic and it will go back to its original state after being stretched.

Spring mechanism:

I felt that my group was very coordinated and the chemistry among us were very strong, which led us to complete the design with much time left.

• Jianye & Jian Lun were focusing on constructing the obstacles for the pinball machine
• Alex & I were focusing on the flippers and spring mechanisms
• Brice was focusing on the base of the pinball machine

These can be seen from the pictures Brice took shown below:

However, after completing our cardboard pinball machine, we quickly realised that the flippers were not able to produce enough force and power to push the marble up as the marble was heavy. 

This led to my team and I to feel very disappointed and hopeless. BUT we did not give up and continued to brainstorm on what could be done to ensure that it still works.

Thankfully, I realised that we can substitude the flippers with a lever instead. A lever can produce more power and it will be able to push the marble up by controlling it manually. Without further ado, I began to install a lever on our design.

Our new design:

Here's a video on our design succeeding in keeping the marble in constant motion for 30 seconds:

Here's a video on us explaining our initiate design and final design:

Here are also some pictures we took as a team :D

Learning Reflection:

Personally, I found this practical very fun and exciting. It allow us to understand and learn the concepts and mechanisms behind some of the marble games we might have come across as a kid such as pinball machines. 

I am happy with our team's results despite us failing and I am grateful that we persevered and did not give up when we faced challenges during the practical.