Mechinacal toy

EXAMPLE USE OF A CAM

Below is a typical use of a cam. A simple toy based on a cartoon character (Ed the Handyman) is controlled by a cam and follower. As the cam rotates in an anticlockwise direction, the follower falls (diagram 2) and so does the arm of the toy. As the cam continues to rotate the arm begins to rise as seen in diagram 4. The cam shown is a pear shaped cam (named after its shape).

CAM PROFILES


Cams can be shaped in any number of ways and this is determined by the way the follower is to move. The shape of the cam is called the PROFILE. Examples of various cam profiles can be seen below.

Pear shaped cams are used on the shafts of cars. The follower remains motionless for about half of the cycle of the cam and during the second half it rises and falls.

Circular cams or eccentric cams produce a smooth motion. These cams are used in steam engines.

Heart shaped cams allow the follower to rise and fall with ‘uniform’ velocity.

What type of movement do you think this cam profile will give ? Drop cam

Wood

Wood can be classified into:

1) Natural Wood (Solid Wood)

It can be further classified into Hardwood and Softwood.

Hardwood: -Deciduous Trees

- Broad leaves, they shed at certain time of the year

- Flowering

Examples: Jelutong, Dark red meranti , Ramin, Teak, Chengal
Meranti Tree
Softwood: - Coniferous trees

- Narrow, needle-like leaves and do not shed.

- Non-flowering

Examples: Fir, Pine
Pine tree
2) Processed Wood (Manufactured Board)

Examples: Plywood, Medium Density Fibreboard, Hardboard, Chipboard

Plywood

Tools

For Marking out materials

Try Square- Checking squareness using datum references.

Scriber- Marking lines on metal.


Dot punch- For punching small dots along a scribed lin in metals

Marking Gauge- Marking lines parallel to a face side or a face edge on wood.



For cutting/working with materials

Tenon Saw- For cutting staright lines on wood.

Coping Saw- For cutting thin pieces of plastics, including curves


Hacksaw- for cutting straight lines in metals


Wooden Mallet- For striking a firmer chisel


Round File- For filing holes or for enlarging a hole



Triangular File- For filing materials

Materials

Colours

Lines

LINES ___________________ <- that's a line! Lines are probably the basic element of design. They are very useful as they indicate lots of essential information like position, direction, and movement. Today, I will introduce to you the types of lines.1) Vertical lines -demand attention

2) Curved lines- represents smoothness and gentleness

3) Lightning blots and eletrical signals- protray electricity and action
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

4) Wavy lines- convey a flowing movement @@@@@@@@@@@@@@@@@@

Aesthetics

Aesthetics is about the look and feel of a product. The two very important qualities play a very important role when you are selecting a product to buy, as it affects your senses and emotions. For example, when you are buying a sofa, you may ask yourself whether it suits your needs, whether the design looks nice, whether it feels comfortable etc. You will repeat these questions for each sofa, until you are satsfied with one.Aesthetics appeal is not the same for everyone, different people have different likes which may be influenced by the following factors:

1) Lines
2) Shapes
3) Forms
4) Colours
5) Textures

Design Process

RICH PICTURE
At the beginning of the project place the theme at the centre. Put words / themes that are connected to it, around it.

DESIGN PROBLEM AND DESIGN BRIEF
State the design problem clearly. Explain how you intend to solve it in general terms.

ANALYSIS
List as many questions as you can about the project you are attempting. E.g. What materials can I use ?What safety considerations must I keep in mind ?

SYNTHESIS
Answer the questions in the analysis.

PLANNING
Use a time chart and flow chart to plan your use of time. (See additional sheet)

RESEARCH
If you are to get a high grade you must put effort into this section. Remember, all research must be relevant to your project and constantly refer to the problem you are trying to solve. Produce at least one sheet on each of the following:Suitable materials for your project.
Investigate the ways in which materials can be joined together - joints and fixings.The ergonomic factors that apply to your project.Safety factors related to your design problem.Write letters to manufacturers / shops.Research using the library.Research using the Internet / CD-ROMs/DVDs.Interview people with the aim of helping you to solve the design problem (record the interview).Carry out a survey / questionnaire and present the results as a pictogram/table of results.Collect pictures of existing products - photographs/catalogue pictures.How are existing products manufactured?Research other relevant areas such as electronic circuits.

SPECIFICATION
Once you have completed your design you should specify in a paragraph or two what exactly you are going to do to solve this problem. Always refer to your research.

IDEAS
Draw at least six ideas, with notes. The ideas should be different and not just the same idea slightly changed. Include environmental considerations (See additional sheet)

DEVELOPMENT
To get the higher grades you must take your best idea and develop it further. One way of starting this section is to draw your best idea again and point out areas that can be improved. Areas may include, safety, colour scheme, cost, using a spreadsheet, shape, materials, mechanisms, circuits, systems diagram and the environment. You must show that you have considered Safety and the Consumer. You also need to develop a circuit for your project. You may need to show how mechanisms can be used as part of your design. How will all the parts/components be joined together? What joints and fixings will be needed? Stages of programming a microcontroller circuit (flow chart). Make a series of models.

SOLUTION
Produce a working drawing of your solution with a parts list. This must have measurements and constructional details. You may prefer to produce a Parts Sheet first. A three dimensional drawing can also be attempted.

MANUFACTURE
Produce planning sheets to show each stage of production - a flowchart, time chart, sequence drawing.Make a model.Make the solution.

EVALUATION
Do not forget this important section. Evaluate your product. State the good and bad points. Does the solution answer the design brief ? Spend some time on this section. You should include social issues, health and safety, ethical and environmental issues.

General WOrkshop Rules

GENERAL WORKSHOP RULES
1) No workshop practice is to be carried out by pupils without the presence of the teacher/instructor.

2) Always use he right tool for the right job and return it to its proper place after use.

3) Extreme care should be exercised when handling sharp-pointed or sharp-edged tools.

4) Do not use tools that are blunt, badly worn, mushroomed or in poor condition.

5) Pupils should not operate machines unless they have been instructed upon their correct use.

6) Report any damage to machines or equipment as this could cause an accident.

7) Always wear an apron as it will protect your clothes and holds lose clothing in place.

8) Wear good strong shoes. Slippers and sandals are not allowed in the workshop.

9) Shirts with long sleeves, watches, rings, bracelets and bangles should not be worm during workshop sessions.

10) Female pupils with long hair should wear a scarf or a headband to keep the hair form becoming a hazard during workshop practice.

11) Do not rush. Watch your steps while in the workshop.

Design And Technology