Drawing to Communicate: The Basics of Technical Drawing

Welcome to Technical Drawing Theory!
(in preparation for your Technical Drawing Theory Quiz).

By

• Communicates design ideas clearly

• Used by engineers, designers, builders

• Shows size, shape, and details of objects

• Helps avoid confusion or errors in making a product

• It's a universal language for design

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What is the purpose of technical drawing?

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• Item

• Item

Multiple Choice

What is the main purpose of a technical drawing?

• To make art

• To explain design ideas clearly

• To decorate a product

• To confuse builders

• Shows 2D views of a 3D object

• Common views: Top, Front, and Side

• Drawn using a method called third-angle projection

• Each view lines up using projection lines

• Used to build, manufacture, or assemble parts accurately

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​Understanding Orthographic Projection

Multiple Choice

Which view is shown in this image?

• Front view

• Top view

• Side view

• 3D view

• Visible line – solid, shows object edges you can see

• Hidden line – dashed, shows edges you can't see

• Centre line – thin and dashed with long/short, shows symmtry

• Dimension line – has arrows, shows how big something is

• Projection line – thin line to align views

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​Line Types in Orthographic Drawing

Match

Match the following

Visible Line

Hidden Line

Centre Line

Dimension Line

• Visible Line

• Hidden Line

• Centre Line

• Dimension Line

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• Keep dimensions clear and neat, not crowded

• Place them outside views where possible

• Use consistent units (e.g. mm)

• Don’t repeat dimensions

• Use leader lines and arrows to point to features

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​Dimensioning Rules

Multiple Choice

Where should dimensions be placed?

• Inside the object

• On top of the object

• Clear space outside the view

• Anywhere you want

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• Adds detail and realism to drawings

• Shading shows light and shadow (depth)

• Rendering shows material (wood, metal, plastic)

• Use different pencil pressures or markers

• Light source direction affects how shading looks

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Shading and Rendering Techniques

Multiple Choice

What does rendering help communicate?

• Texture, material and form

• Random colours

• Line thickness

• Nothing important

• T-square – draws straight horizontal lines

• Set square – draws vertical/angled lines (30°, 45°, 60°)

• Compass – draws circles or arcs

• Scale ruler – used for accurate measurements

• Drawing board – flat surface to keep work aligned

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​Using Traditional Tools

Multiple Choice

Which tool would you use to draw a circle?

• Set square

• Ruler

• Compass

• T-square

• Tinkercad – beginner-friendly, easy 3D modelling

• Good for learning shapes and how things fit

• Autodesk Inventor – industry-level software

• Allows detailed engineering drawings and simulations

• CAD tools help test and change designs before making them

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Digital Tools – Tinkercad and Inventor

Multiple Choice

What is the main benefit of using CAD software?

• Drawing by hand is faster

• It’s easier to erase

• CAD improves accuracy and editing

• You don’t need measurements

• Choose eco-friendly or recycled materials

• Design for re-use, not just one-time use

• Reduce waste during production

• Think about energy use and product lifespan

• Design for repair, not just replacement

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Sustainability in Design

Multiple Choice

Which choice supports sustainable design?

• Using recycled materials

• Using rare tropical wood

• Ignoring waste

• Making single-use items

• Make products usable by all people (inclusive design)

• Avoid copying other people’s work (plagiarism)

• Use materials that don’t harm people or the planet

• Think about who benefits and who might be left out

• Design with fairness and responsibility

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​Ethics in Technical Design

Multiple Choice

Which of these is an ethical design choice?

• Designing a product only for men

• Choosing low-cost but harmful materials

• Making a product accessible for all users

• Copying someone else’s work

Multiple Choice

You are designing a phone holder. What views would you include?

• Only the front view

• Front, Top, and Side views

• Perspective only

• Side view only