# BUILDING A SIMPLE MACHINE FROM LOCAL MATERIALS

Frank Anamuah-Koufie

Introduction

The objective of the task was design a system of machines capable of moving a small ball (6cm diameter) across a distance of one metre into a goal area. The goal area has dimensions 25cm X 25cm X 10cm. the mechanism is designed to be touched once and be “automated” for the rest of its course.

Design

The following constraints affected the design of the machine:

1. The machine must be composed of locally acquired materials only.
2. Materials purchased in building the machine should not cost more than GHC20.00.
3. The machine must be composed of a minimum of four simple machines.
4. The machine may only be touched once, the purpose of which is to get it started.

The constraints listed above naturally limited the options we had in designing a solution. However, it also paved way for creativity and new thoughts about possible uses of some materials that were considered to be waste materials or would have never been considered in the building of mechanical systems.

Concept

We pictured the machine in terms of the stages involved in accomplishing the task. These were:

1. Picking up the ball
2. Moving the ball across the distance
3. Dropping the ball in the goal area

In picking up the ball, we considered several options that included having an arm attach a metallic tape to the ball and picking the ball up with an attached magnet. We also came up with a “dustpan and broom” mechanism that would “sweep” the ball from the floor unto a “launch pad”.

We considered three possibilities for moving the ball across the distance. The first option was to “fly” the ball using a catapult or lever mechanism from the machine directly into the box. The second consideration involved rolling the ball on the ground from an inclined plane straight into the box. But this was based on a misconceived idea that the goal area would have a front-facing opening rather than the upward-facing opening it had. Our final consideration was to have the ball drop from a height and then bounce into the box in a calculated number steps.

One option for dropping the ball required actively dropping the ball into the goal area by turning of an electromagnet that would be mounted on an arm carrying the ball across. The other options were simply passive results of the “moving process” and as such would not require a deliberate attempt to drop the ball.

Each of the three steps were tested independently to ascertain their efficacy before being tested together to see how the whole system may work.

Implementation

We chose to use an iterative process in building the machine. The steps involved were designing, building and testing in that cycle respectively. We began with 2 days of brainstorming and sketching our initial ideas on paper. At this stage, we considered no physical limitations and allowed all sorts of ideas to flow.

The next step, which involved building models, was more realistic. At this stage, we focused more on the physical challenges that the machine may face. We considered weight limitations, material limitations and the role certain forces such as gravity and friction would play on the functioning of our machine.

Our first model involved 3 simple machines; a pulley to release a calculated weight onto an inclined plane. The weight would then slide down the plane and gather momentum enough to catapult the ball from one end of a simple lever into the goal area.

Our tests revealed a number of challenges and provided some new insights into building the machine. We realized that using a stone as our weight was difficult because we could not control the weight and it was also difficult to get the ball rolling on the inclined plane. Another challenge we encountered was getting the pulley to support two heavy stones. Theoretically, we thought the two would balance themselves but in reality, they put a lot of strain on the pulley and almost split the wooden support.

After several iterations, we finally came up with a design that was composed of three simple machines, not meeting all the basic requirements of the challenge. The final machine instead of having one human intervention point had two. The final design was composed of two inclined planes and a lever. The lever and inclined plane we put together using pieces of wood. We used a sock filled with sand as the weight in place of a stone because it was easier to adjust the weight. The mechanism employs four energy transfers:

1. At one end of the machine, a rubber band holds the weight in place and a wedge holds the ball at another end.
2. The rubber band is released and at that instant, the wedge is turned.
3. The ball and weight move down the two planes with the ball arriving on the “launchpad” first. This is because the ball is lighter and moves on a shorter inclined plane.
4. The weight, which is a sock loaded with sand is much heavier and on a longer plane so arrives later at the other end of the lever.
5. The weight lands on one end of the lever and shoots the ball into the box.

Materials Used

1. Plywood – for inclined planes and lever
2. Sand – Weight
3. Sock – Container for weight
4. Rubber band – Trigger
5. Nails and kebab sticks – for nailing components together.

Conclusion

This task has opened our minds to new ways of thinking about some of the local materials scattered around us. It has also shown us how some ideas may look very simple on paper but can be gruesomely difficult to build in the real world. It is indeed a perfect introductory work to a class in robotics as it has made us appreciate the importance of robots in our activities.

# Task 1: Building a Machine Out of Locally Available Materials

Group Members:

Flynn Darko

Emmanuel Nkansah

Robotics

Dr. Ayokor Korsah

Introduction & Objective

Our main task for this robotics class was to build a machine using locally available materials that would transport a ball to a box or goal area, one or more meters away. We were also required to implement in our machine four simple machines such as the lever, pulley and a wedge. We had approximately a week to complete this task. Initially, our impression of the task was one of ease. However, the implementation proved more difficult than we expected. The machines we drew and imagined reacted differently in the reality and hence required some adjustments to the blue print several times, many of them spontaneously.

Design Concept

After thinking through how we could implement this task using simple or compound machines we decided on four simple machines. This included a pulley, two inclined planes, a wedge and a lever as can be seen in figure 1.

Figure 1. Use of four Simple machines in building our own machine

Subsequently, we put together the four simple machines to come up with a machine we called “Universe.” The concept features an inclined plane that will transport a ball from its place of origin onto a cup like container that is fastened to a lever placed adjacent a pulley. The job of the pulley is to apply a force to the other side of the lever in order to propel the ball into the goal area (box). The universe machine concept can be seen in figure 2.

Figure 2. Sketch of what the whole machine would look like

Figure 3. Snapshots of Universe

Figure 4. Snapshots of Universe

Implementation

The materials we used to build our machine consisted of plywood board, stone, plastic bottles, paper card and nails. The lever, pulley as well as the wedge were made using the plywood provided. Furthermore, we acquired Tampico bottles from the recycle baskets on campus to enable us create the ball holder. This was not a simple process as many (almost all) of the bins contained only “voltic” water bottles which were too weak to serve as a pulley. The Tampico bottles we found were sawed at the base to obtain the cup-like ball container. Some of the difficulties we faced involved splitting the plywood due to the size of the nails being used on them. Furthermore, it was increasingly difficult to find materials on campus that fit our concept hence we were required to improvise for the plan to be implemented successfully.

Discussion

As already mentioned, building this machine from locally available materials proved to be a challenging. For instance, in building a stand for the pulley we could not figure the height that it should be to give as the perfect projection of the ball placed on the lever. Upon giving it a number of tests we had to change the stand to a much smaller one to get the desired outcome. Also, finding the right stone size and weight to propel the lever proved difficult. However, our machine worked as we desired though we could have adjusted the sizes of our materials for more accuracy in getting the ball into the goal area.

Conclusion

Building our machine proved educative and challenging in that it thought as ways we could reuse waste materials to build useful machines and how that requires creativity and careful thought. It also gave us an amazing foretaste of the robotics course. The experience put our creativity side to the test hence proved interesting. However, our inexperience in carpentry led to time overhead and a longer building process. Nonetheless, we look forward to doing more hands on work in this course.

# Task 1 – Simple machine

Report for Robotic Class Task One on Tuesday, September 18, 2012 by Daniel Botchway and Keith Arthur

# Introduction

The requirements of this first task were to design and build a complete machine. This machine was to be made up several simple machines built out of locally available materials that would move a ball from a resting place to a goal area that was at least 1 meter away. The task had a 12-day timeline from start to its completion and final demonstration of the inventions.  The overall aim of this project was to get the students of the robotics class to explore the engineering aspect of the class while having a direct hands-on experience with the building of mechanical devices.

# Design Concept

Coming from a computer science point of view, we took an object-orient approach to the designing of the machine. This meant we developed a concept of the machine by indentifying and defining the entire machine into key parts that had specific roles. The process of modularization of the machine allowed us to carefully consider what we needed and what machine would be suitable in achieving that goal.

# Implementation

We divided the machine into four simple modules. These are (i) lift module (ii) drop module (iii) cut module and (iv) launch module.

This is the lift model which consists of the domino effect which pushes the ball into the tray to be lifted by the help of the pulley, which has a load connected to it to pull the ball upwards to transport it to the next module.

This is the drop module, which receives the ball after it has been lifted up by the pulley system. The ball is then transported on the incline plane to the next model which consists of a catapult – cut model.

This is the cut model which receives the ball from the drop model. A branch is used as the catapult system which is tied to create the tensional force for displacing the ball into its destination. The fire below the rope is used to release the branch to succeed with the catapulting.

Finally, the launch model is initiated as the branch is released and then reaches for its destination – the box.

# Discussion

The idea was very unique and quite different from our fellow mates but we realized that visualization is not the same as seeing your idea being implemented physically. We had a tough time with every part of the model because we encountered physical laws like gravity and force that would not let us go free without obeying them. We had to adjust some parts of each model like the lift model. Instead of allowing the dominos to push the load responsible for lifting the tray with the ball in it, we caused water to drip into an empty container to lift the ball up . Furthermore, we learnt how to saw wood and hammer nails into wood.

# Conclusion

It was a tiring task because we spent hours on figuring how to build a machine that will throw a ball into a box, 1 meter away. However, we acknowledged engineers, architects and people who build structures because it is not as easy to build what you see on paper or the ideas you have generated.

18/09/2012

Abdelrahman Barakat

Selase Attah Kwamuar

Introduction:

The task is to build a machine. The purpose of the machine is to get a small ball into a goal area, subject to some specified restrictions. The machine should be able to move the small ball provided from a resting position on the floor to a goal area at least 1m away. The machine must have at least 4 steps (i.e. it must be made up of at least 4 simple machines). The diameter of the ball is about 6 cm and the dimensions of the goal area are about 25 cm x 25 cm x 10 cm.

Design Concept:

We started by brainstorming about how to get 4 simple machines to move a ball from a resting position to a goal area that is at least 1m away. We come up with a sketch that can move the ball from a resting position to another resting position. Figure 1 depicts the first sketch.

Figure 1

In figure 1 the simple machines includes a wheel, pulley, lever and incline plane. The purpose of these machines is to help with precision. We want to control errors as much as possible.  The rationale behind this concept is that we will put the ball on the left side of the lever and a load on the right side of the lever and then we tire a rope at the left side of the lever where we have the ball at a resting position in a container. With the help of the rope, wheel and the pulley we will pull the lever to an appropriate position. Once we release the rope, the lever propels the ball onto a resting plane and then the ball moves onto the incline plane onto another resting position.  Figure 2 depicts the machines that we added to it.

Figure 2.

As depicted in figure 2 we added another lever to the machine. The lever will propel the ball from its resting place to the goal area.

Implementation:

Below are the materials that we used to build the machine;

Plywood,

Ropes and strings,

Elastic (rubber band),

Pulley (office chair wheel),

Plastic bottles,

Nails,

Super glue,

Stones,

A candle,

Matches.

Figure 3 depicts the machine.

Figure 3.

Step 1

We started by sawing the plain plywood to get our inclined plane from it. We formed an incline plane by fabricating 4 rectangular plane. After that we created a resting plain that would hold the force of the ball. That was also fabricated by sawing 5 pieces of plains from the plywood.

Step 2

We created two levers. The lever comprises of a pivot, a load and an effort.  The pivot was made up from a wire mesh. The bar was made up from a long bar and the load from a stone.

Step 3

We drilled the pulley into the plywood that is holding the machine. We also put our wheel on a stand such that we could control how far the ball will be thrown away from the lever.  We then tied a string to the first lever through the pulley and finally to the wheel.

Step 4

The ball lands on an inclined plane which we made out of plywood. The inclined plane moves the ball to a second lever which works as a catapult.

Step 5

Our second lever has a cut bottle that holds the ball and a rubber band (elastic). This makes it possible for the ball to be catapulted to the goal area. We used a candle to trigger the release of the lever when a string is burnt.

Result:

The ball was able to move successfully 1m away from the machine to the goal area.

Conclusion:

The task is very challenging. The ideas were really not forth coming in the beginning but as we started implementing the ideas we got more ideas to make the machine work properly.

Date: January 30, 2012

Option 1:

In the spirit of the African Cup of Nations, the purpose of your machine will be to get a small ball into a goal area, subject to some specified restrictions. Design and build a machine that can move the small ball provided from a resting position on the floor to a goal area at least 1 m away. The diameter of the ball is about 6 cm, and the dimensions of the goal area are 25 cm by 25 cm by 10 cm.

In this task, the main materials that my team used were:

1)      Cardboard

2)      Bathroom slippers

3)      Khebab sticks

4)      Electric Motors

5)      String

6)      Cello tape

7)      Glue

8)      Wheels

9)      Switches

10)  Wires

11)  Batteries

The machine:

We decided to design and build a machine that will pick up the ball, move to the goal area, and then drop the ball into the goal box. Given time constraints, we couldn’t build the machine to pick up the ball from the ground. However, when given the ball, the machine was able to move to the goal area and drop the ball into the goal box. Listed below are some simple machines that our machine was made up of:

1)      Lever

2)      Inclined plane

3)      Wheel and axle

4)      Pulleys

5)      wedge

Mechanics:

Two electric motors were used in the construction of this machine: one was used to power the machine to move, and the other was used in the pulley system (will be explained shortly). The electric motor that drove the machine was located at the rare of the system. It had an 8 tooth gear that drove a bigger gear of 16 teeth (1:2). The rationale behind allowing the small gear to drive the bigger one was to increase the torque and decrease the speed of the motor. The bigger gear was connected to an axle, which in turn connects to the two rare wheels. When the 9 volts battery was connected and the circuit closed, the back wheels rotated. The front wheels freely moved as a result of the push from the rare wheels. Sitting on the base of the machine were two piers made of cardboards. They both function as a lever and an inclined plane. A wedge-like cardboard, which carried the ball into the goal area, sat on top of the two piers. As a lever, the ball and the wedge-like cardboard container balances themselves on the edge of the tallest pier. When the car hits the goal box, the electric motor on the front of the car is triggered which pulls the string attached to the underside of the wedge-like cardboard. This board then slopes forward and rest on top of the shorter pier, functioning as an inclined plane. At this point the ball rolls down the inclined plane into the goal box.

Below is the sketch of the proposed machine.

The images below show the various parts of the machine after completion.

Fig 1.1: the wedge-like cardboard sitting on the two piers. At this point the machine functions as an inclined plane.

Fig. 1.2: The front view of the machine showing the front electric motor that support the pulley system

Fig 1.3: The wedge-like cardboard functioning itself as a lever on the tallest pier.

# Task #1 – ball-throwing machine

The ATD 3000 [Attention To Detail 3000]
ATD 3000 was a machine that consisted of four simple machines: 2 inclined planes, a lever and a pulley. The Computer Science Department provided some plywood, a hammer, a rope, nails and a saw as resources for the completion of this task. Other raw materials such as, shoe ‘hoofs’, hangers, carpenter’s glue and a biscuit container had to be secured by the team members to aid the building of the machine.

Design Concepts