Lesson Notes By Weeks and Term v5 - Grade 12

Lesson Video

This page supports the lesson note with a companion video and a short classroom-ready summary.

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Performance objectives

• Review and refine your existing PAT work.
• Apply specific EGD principles correctly.
• Manage your time to complete key sections.
• Effectively use resources like CAD software and textbooks.
• Document your progress and challenges.

Lesson summary

This week marks a critical stage in your Grade 12 Engineering Graphics and Design (EGD) journey. We are focusing intensely on ensuring your portfolio and Practical Assessment Task (PAT) are progressing according to schedule and meet the required standards. Remember, the PAT contributes significantly to your final mark and showcases your accumulated skills and understanding of EGD principles. Successful completion of the PAT is not just about passing the subject; it’s about demonstrating your readiness for future studies or careers in engineering, architecture, and design-related fields.

Lesson notes

This week is dedicated to consolidating your existing PAT work. This requires a thorough understanding of the PAT requirements, assessment criteria, and relevant EGD principles.

Let's break down the key aspects: a)

Understanding the PAT Requirements: The PAT is designed to assess your ability to apply EGD principles to solve a practical design problem.

It typically involves: Problem Statement: A clear description of the design challenge. You should fully understand the constraints, specifications, and desired outcome.

Design Process: This includes preliminary sketches, concept development, alternative solutions, and justification for your final design choice.

Working Drawings: Accurate and detailed orthographic projections (front, top, side views) of your design, including dimensions, annotations, and symbols.

Isometric or Perspective Drawings: A 3D representation of your design to visualize the overall form and appearance.

Development of Surfaces (if applicable): Creating a 2D pattern that can be folded or cut to form a 3D object, often required for sheet metal or packaging designs.

CAD Implementation: Utilizing CAD software (e.g., AutoCAD, Inventor, SolidWorks) to create precise drawings and models of your design.

Assembly Drawings (if applicable): Showing how different parts of your design fit together.

Parts List or Bill of Materials (BOM): A list of all the components required to build your design, including quantities, materials, and dimensions.

Presentation and Communication: A clear and professional presentation of your PAT, including a written report explaining your design process, choices, and any challenges encountered. b)

Assessment Criteria: The assessment criteria will vary slightly depending on the specific PAT assignment, but generally include: Accuracy and Precision: Are your drawings accurate and to scale? Are dimensions correctly applied?

Completeness: Does your PAT include all the required components?

Application of EGD Principles: Do you correctly apply orthographic projection, isometric projection, development of surfaces, and other relevant EGD principles?

CAD Proficiency: Do you demonstrate effective use of CAD software?

Design Functionality: Does your design meet the specified requirements and constraints? Is it practical and functional?

Creativity and Innovation: Does your design show originality and ingenuity?

Presentation and Communication: Is your PAT well-organized, clearly presented, and easy to understand?

Adherence to Standards: Does your PAT adhere to SANS (South African National Standards) and other relevant drawing standards? c)

Common EGD Principles: Orthographic Projection: Projecting 3D objects onto 2D planes (front, top, side views) to accurately represent their shape and dimensions. This is fundamental for creating working drawings.

Isometric Projection: A type of axonometric projection where all three axes are equally foreshortened, creating a 3D view that is relatively easy to measure. This is used for visualizing the overall form of an object.

Development of Surfaces: Creating a 2D pattern (development) that can be folded or cut to form a 3D object. This is essential for designing sheet metal parts, packaging, and other fabricated objects. Remember to account for seam allowances!

Sectional Views: Cutting through an object with an imaginary plane to reveal the internal details. Hatching is used to indicate the cut surfaces.

Dimensioning and Tolerancing: Applying dimensions and tolerances to drawings to specify the size, shape, and allowable variation of parts. Adhere to SANS standards for dimensioning practices.

CAD Skills: Proficiency in using CAD software to create accurate and detailed drawings, models, and assemblies. This includes using commands for drawing lines, circles, arcs, polygons, applying dimensions, creating layers, and generating 3D models. d) Worked

Examples: Example 1: Checking for Accuracy in Orthographic Projection Let's say your PAT requires you to design a simple bracket. You've already created the front, top, and side views in orthographic projection.

Check 1: Alignment: Ensure that corresponding features are aligned vertically and horizontally between the different views. For example, the top edge of the bracket in the front view should align perfectly with the top edge in the side view. Use light construction lines to verify this.

Check 2: Hidden Detail: Verify that all hidden details are correctly represented with dashed lines. A common mistake is forgetting to include a hidden hole in the front view that is visible in the top view.

Check 3: Dimensions: Review all dimensions to ensure they are accurate and complete. Double-check that you've included overall dimensions, feature dimensions, and any necessary tolerances. Use a scale rule or CAD software to verify the dimensions.

Example 2: Applying Development of Surfaces You need to design a rectangular sheet metal duct.