3.1 Freehand Orthographic Projection Drawings

Freehand orthographic projection is a foundational skill that enables architects to quickly communicate spatial relationships without relying on drafting instruments. In the Kenyan architectural context, freehand sketches are often used during site visits, client consultations, and design brainstorming sessions to convey ideas rapidly and clearly before formal drawings are produced.

3.1.1 First Angle Projection

Concept and Layout of First Angle Projection

The first angle projection method is a technique where the object is conceptually placed between the observer and the projection plane. This results in views being projected onto planes behind the object, which are then unfolded into a 2D representation.

• Placement Principle: The object lies in the first quadrant between the observer and the projection plane.
• View Arrangement: The top view is placed below the front view, and the right side view appears on the left side of the front view.
• Projection Planes: The horizontal plane (for the top view) and vertical planes (for front and side views) are used.
• Application: Commonly used in European countries and acceptable in Kenyan architectural practice when specified.
• Visual Understanding: Helps in visualizing the object by unfolding its faces systematically.

Steps to Construct a Freehand First Angle Projection

1. Draw the front view outline of the architectural element or building facade.
2. Project vertical and horizontal construction lines from key points on the front view to establish reference grids.
3. Place the top view below the front view using the projected construction lines to map features.
4. Project lines horizontally from the front view and vertically from the top view to locate the right side view.
5. Draw the right side view on the left of the front view, ensuring dimensions align correctly.
6. Label all views clearly, indicating the orientation and scale (freehand, approximate scale).

Advantages and Limitations of First Angle Projection

• Advantages:
  • Allows clear and standardized interpretation when used correctly.
  • Encourages precise spatial understanding of building elements.
• Limitations:
  • Can confuse students unfamiliar with the reversed layout of side views.
  • Less intuitive for clients or stakeholders used to third angle projection.
  • Freehand nature may reduce dimensional accuracy without instruments.

Typical Applications in Kenyan Architectural Practice

• Sketching initial design concepts during site surveys at county government offices.
• Quick representation of building elevations and floor plans in client meetings.
• Use in architectural colleges for foundational drawing exercises.
• Drafting simple building components such as window frames or door sections.

3.1.2 Third Angle Projection

Concept and Layout of Third Angle Projection

In third angle projection, the projection plane is placed between the observer and the object, opposite to the first angle method. This technique is widely used in Kenya and internationally for architectural and engineering drawings.

• Placement Principle: The object is located in the third quadrant behind the projection plane.
• View Arrangement: The top view is placed above the front view, and the right side view is placed on the right side of the front view.
• Projection Planes: Similar planes as first angle, but views are arranged differently.
• Standardization: Preferred in Kenya for clarity and ease of interpretation among multidisciplinary teams.
• Visual Logic: The layout corresponds intuitively to how an observer views the object from different directions.

Steps to Construct a Freehand Third Angle Projection

1. Sketch the front view of the architectural object with approximate proportions.
2. Extend vertical and horizontal construction lines from the front view to create reference points.
3. Position the top view above the front view, projecting key features vertically.
4. Project lines from the front view horizontally to the right to locate the right side view.
5. Draw the right side view on the right side of the front view, ensuring alignment of dimensions.
6. Annotate views with labels and directional indicators such as arrows or symbols for clarity.

Benefits and Challenges of Third Angle Projection

• Benefits:
  • Intuitive layout that matches the observer’s natural viewing direction.
  • Facilitates easy understanding by clients and construction teams.
• Challenges:
  • Requires discipline to maintain consistency in freehand sketches.
  • Potential for dimensional inaccuracies without measuring tools.
  • May be confused with first angle projection if symbols are not clearly indicated.

Practical Uses in Kenyan Architectural Settings

• Conceptual design presentations in architectural firms and consultancies.
• Visualizing building sections and elevations quickly during design reviews.
• Training students in architectural drafting at technical colleges.
• Preparing rough site plans and building layout sketches for informal client approvals.

Chapter Summary

This chapter focused on producing orthographic drawings, starting with freehand orthographic projection techniques. It covered the principles and construction of first angle projection, followed by third angle projection, highlighting their key differences and applications. The chapter then progressed to creating scaled orthographic projection drawings, detailing step-by-step procedures for both first angle and third angle projections to ensure accuracy and adherence to standards. Emphasis was placed on selecting appropriate scales and maintaining correct proportions throughout the drawing process. Finally, the chapter addressed the dimensioning of orthographic elevations, explaining how to accurately annotate drawings in both first angle and third angle projection methods. Proper dimensioning techniques were demonstrated to enhance clarity and facilitate interpretation of technical drawings. Throughout, the importance of conforming to established drawing standards was reinforced to produce professional and reliable orthographic representations.