Blog Entry 6

 Week 13: Operating Principles and Mechanism Design

This weeks lesson is about operating principle of design, apparatus and equipment and 6 different types of mechanisms. 

Operating principles:

Most devices and equipment are based on these four working principles which are

• Mechanical
• Electrical
• Chemical
• Magnetism

There are many everyday devices that function based on these working principles such as 

Brewing coffee

 

Brewing coffee involves the leaching of coffee soluble 

Foil shavers

Foil shavers work based on reciprocating motion

For our chemical product in CA1, the working principle is based on heat transfer.

Mechanism:

Why mechanism? Mechanisms are often required for devices to operating smoothly and efficiently.

There are 6 essential mechanism in functional prototypes which are:

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

1. Actuators

Converts stored energy into motion. Stored energy is usually in the form of compressed air, electrical potential or liquid pressure.

2. Cams

Converts the rotation of a shaft into simple or complex reciprocating linear motion.

3. Gears

Transmit torque and to adjust rotational velocity

4. Lever

Transmit and amplify force by fixing the input and output about a function a fulcrum or pivot point

5. Ratchets

They lock in one direction, allowing them to tighten without the fear of literally 'going back'

6. Springs 

Store and dissipate energy

For the next activity, we were tasked to design a ping pong ball launcher that can shoot and reload ping pong balls.

Practical 4: Game Design with Cardboard

For this practical, we are to design and make a marble machine out of cardboard which is able to keep a marble in continuous motion for at least 30 seconds.

Looking online for inspiration, we stumbled across a marble stair machine which took inspiration from.

1. Sketching and calculating the dimensions of our design

We sketched how tall the support is going to be which is 55cm.

We used one of the cams mechanisms which is the small circle to move pieces up and down.

The steps are cut at an angle to allow the marble to slide down.

The big circle is use as a slide for the marble to roll down.

2. Drawing and cutting the pieces 

First we cut out the slopes part from 4.5cm to 11.5cm with an increment of 1cm, we cut 8 pieces to make 2 levels. We glued 4 of the pieces together to make it thick enough to the marble to roll on. 

We then cut the big piece of cardboard which is the base to put the slopes on it. 

We cut a long piece of cardboard to be used as a strap to hold the slopes in place when the game is put to a 45 degree angle.

We then cut out 32 pieces of the small circle, glued 4 of them together and wrap the edge of it with cardboard paper to make the cams.

We used wooden stick and insert the circles we made earlier to make a rotary device. However, the circles tend to move around so we secured them with masking tape.

We cut out 6 big circles and cut slip on each circle to connect all the other circles to form a figure 8 slope

We cut 2 long and sturdy pieces of cardboard to hold the figure 8 slope up.

3. Time lapse of us assembly the marble game

Product in operation

Reflection

Overall, the practical was fun as get to design whatever we like, however for our group, I feel that we did not plan enough for this practical which caused us to have a failed working mechanism as the we made the base too small and the straps hold the slopes too tightly which resulted in the slopes not able to move up and down when turning the cams. Before the start of the practical, we should have better prepared and test if the mechanism will work when we assemble it.