Textbook References:
JCTG: Junior Certificate Technical Graphics (O’Callaghan)
UTG: Understanding Technical Graphics (O’Sullivan)
WS: Worksheets
Webpage:
In order to draw tangents to circles you must understand the theorem that the angle of a triangle inscribed in a semi-circle is always right angles, here is a Youtube video to show you (https://www.youtube.com/watch?v=flUfBct_iZ0)
Specialist equipment required for class
• HB, H and 2H pencil
• Pencil sharpener, eraser
• Colouring pencils
• 45, 30 and 60 degree set-squares
• Compass
• Drawing clips or masking tape
• A3 Folder
• Textbook: Understanding Technical Graphics
• Piece of paper/card for a trammel (template)
• iPad
Equipment required at home
• T-square
• Drawing Board
• Internet connection and access to SharePoint
Keywords
- Circumference
- Arc
- Chord
- Diameter
- Semicircle
- Quadrant
- Segment
- Radius
- Sector
- Secant
- Concentric
- Eccetric
- Diameter
- Simicircle
- Volkswagen
- Tangent
- Contact
- Equilateral
- Triangle
- Auctioneers
- Trophy
- Radius
- Construction
- Guaranteed
- Ellipse
- Cylinder
- Major
- Auxiliary
- Umbrella
- Entrance
- Quadrant
- Trammel
- Method
- Shampoo
- Rectangular/Rectangle
- Tangent
- Normal
- Significant
- Initally
Scheme for this topic
Sheet 1
- Line out an A4 sheet with the 10mm margin and title block at the bottom (10mm (construction line), 5mm (construction line) and 10mm (Heavy line) from the margin )
- Fill in your name, SHEET X: CIRCLES 1 and the date
- Examine the diagrams on page 84. You will draw two large circle on to your sheet initially
- Measure 70mm vertically and draw a light line across the page (This is the centre line for the large circles)
- Measure 70 mm horizontally, this is the centre for the first circle of radius 50mm
- Measure a further 140mm, this is the centre for the second circle of radius 50mm.
- Lable the parts of the circle using the diagrams on page 94
- In the area around the two large circles draw two further diagrams to represent concentric and eccentric circles as shown on page 94. The radius sizes of these are not significant.
Sheet 2
- Line out an A4 sheet with the 10mm margin and title block at the bottom (10mm (construction line), 5mm (construction line) and 10mm (Heavy line) from the margin )
- Fill in your name, SHEET X: CIRCLES CAR and the date
- Examine the diagram of the 'Circle Car' attached below.
- Measure 70mm vertically up from the title box and draw a light construction line across the page
- Measure 55mm along this line. This is the centre for the circle that forms the front of the car.
- Complete the diagram using the measurements given. Light construction lines should be used initially to form an outline of the significant points, including the centre points. The circles should be the last to be and heavy to avoid having to go back over the circles/arcs.
Sheet 3
- Line out an A4 sheet with the 10mm margin and title block at the bottom (10mm (construction line), 5mm (construction line) and 10mm (Heavy line) from the margin )
- Fill in your name, SHEET X: OPEL INSIGNIA and the date
- Examine the diagram of the 'OPEL' sign on page 95
- Measure 120mm vertically up from the title bar and draw a light line over half way across the page
- Measure 180mm along this line. This will provide the centre for the Opel Insignia
- Draw an outline of the diagram as shown, lightly at first then in a darker pencil
Sheet 4
- Line out an A4 sheet with the 10mm margin and title block at the bottom (10mm (construction line), 5mm (construction line) and 10mm (Heavy line) from the margin )
- Fill in your name, SHEET X: BMW INSIGNIA and the date
- Examine the diagram of the 'BMW' sign on page 95
- Measure 120mm vertically up from the title bar and draw a light line over half way across the page
- Measure 180mm along this line. This will provide the centre for the Opel Insignia
- Draw an outline of the diagram as shown, lightly at first then in a darker pencil