A2.2.2 Drawings in the design process Notes

Why Designers Use Drawings

Drawings, either manual or CAD, are used to:

1. Exploration: Visualising initial ideas and concepts.
2. Refinement: Iterating and improving designs.
3. Communication: Conveying ideas to stakeholders, including clients, engineers, and manufacturers.

Informal Drawing Techniques

Freehand Sketching

1. Informal, fast drawings to visualise ideas
2. Used in the early concept stage

Formal Drawing Techniques

Orthographic Projection

1. Orthographic projection involves creating multiple views of an object (e.g., front, top, side) to represent its dimensions accurately.
2. They are essential for manufacturing, as they provide the detailed specifications needed for production.
3. Used for final design communication.

Note

• Orthographic drawings use projection symbols to indicate whether they follow:
  • first-angle
  • third-angle projection.
• These symbols help engineers and manufacturers interpret the layout of views correctly.
• First-angle is most commonly used in Europe, with third-angle used in UK and USA.
• The IB uses third-angle projection as standard.

Key Elements of an Orthographic Drawings

1. Title block (with student/designer name, scale, date, drawing number)
2. Third-angle projection symbol
3. Front, top, and side views (typically three views, aligned correctly)
4. Dimensions (clearly labelled with consistent units)
5. Scale (noted in the title block or near the drawing)
6. Hidden lines (to show features not visible from that view, such as dashed lines)
7. Centre lines (for circular features or symmetry, long dash followed by a short dash)
8. Consistent line weights (thicker for visible outlines, thinner for hidden or construction lines)

Assembly Isometric Drawings

1. Isometric drawings represent three-dimensional objects on a two-dimensional plane, maintaining equal scale along all axes.
2. Assembly drawings show how components fit together.
3. Can be exploded, sectioned, or fully assembled
4. Often presented alongside a Bill of Materials.
5. Used in the refinement / presentation stage

Exploded Drawings

1. Exploded drawings show how components of an assembly fit together.
2. Used for technical / assembly documentation.

The Role of CAD in Design

Benefits of CAD:

1. Precision: Ensures accurate measurements and dimensions.
2. Efficiency: Speeds up the design process with tools for editing and iteration.
3. Visualisation: Allows for 3D modelling and rendering, providing a realistic view of the final product.
4. Collaboration: Facilitates sharing and collaboration with stakeholders through digital files.