Lesson Notes By Weeks and Term v5 - Grade 12

Lesson Video

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Performance objectives

• Finalize all sections of your Portfolio and PAT.
• Critically evaluate your own work for improvements.
• Apply correct dimensioning and annotation techniques.
• Manage your time effectively to meet deadlines.
• Demonstrate proficiency in producing accurate drawings.

Lesson summary

This week is crucial for focusing on the completion of your Engineering Graphics and Design (EGD) Portfolio and Practical Assessment Task (PAT). The PAT contributes a significant portion to your final Grade 12 mark, serving as a tangible demonstration of your acquired skills and knowledge throughout the year. In the South African context, excelling in EGD opens doors to various career paths, including engineering, architecture, design, and manufacturing. A well-executed PAT not only boosts your academic standing but also provides a solid foundation for future studies or employment in these fields, contributing to the skilled workforce needed for South Africa's economic development.

Lesson notes

Understanding the Portfolio and PAT: The EGD Portfolio serves as a compilation of your work throughout the year, showcasing your progress and understanding of the subject. It typically includes a collection of drawings, design projects, and problem-solving exercises. The PAT, on the other hand, is a comprehensive, in-depth project that requires you to apply all the skills and knowledge you've gained throughout the year to solve a specific engineering design problem. The PAT assesses your ability to conceptualize, design, and communicate your ideas effectively through technical drawings and written reports.

Key Areas of Focus for Week 9: Completeness: Ensure all required sections of the Portfolio and PAT are present and accurately reflect the instructions provided in the CAPS document.

Accuracy: Double-check all dimensions, annotations, and geometrical constructions for accuracy. Errors, even small ones, can significantly impact your mark. This is especially important when using CAD software; verify that your drawings are to scale and that all measurements are correct.

Clarity: Your drawings and reports must be clear, concise, and easy to understand. Use appropriate line weights, lettering styles, and symbols. Your writing should be grammatically correct and use technical terminology accurately.

Presentation: A well-presented Portfolio and PAT demonstrate professionalism and attention to detail. Use a neat and organized format, and ensure that all drawings are properly labelled and arranged.

Adherence to Standards: Familiarize yourself with relevant SANS (South African National Standards) for technical drawing. These standards specify conventions for line types, lettering, dimensioning, and other aspects of technical drawing.

Common Errors and How to Avoid Them: Incorrect Dimensioning: Use the correct dimensioning techniques (aligned, unidirectional) and ensure that all dimensions are accurate. _Example_: When dimensioning a circle, clearly indicate the diameter with the correct symbol (ø). When dimensioning a linear distance, ensure the extension lines are perpendicular to the dimension line.

Poor Line Work: Use appropriate line weights to distinguish between object lines, hidden lines, center lines, and dimension lines. _Example_: Object lines should be thick and dark, while hidden lines should be thin and dashed.

Incomplete Annotations: All drawings should be properly annotated with labels, notes, and specifications. _Example_: Clearly label all components of a mechanical assembly and provide relevant information, such as material specifications and manufacturing tolerances. Misunderstanding of Orthographic Projection: Ensure that you accurately represent 3D objects in 2D using orthographic projection. _Example_: When projecting a rectangular prism, ensure that the front, top, and side views accurately depict its shape and dimensions.

Ignoring Sectioning Conventions: When creating section views, use the correct hatching patterns to indicate the material being cut. _Example_: Use different hatching patterns for steel, aluminum, and wood. Ensure that the cutting plane line is clearly indicated.

Worked example

Example 1: Dimensioning a simple component

Imagine you're drawing a simple rectangular metal plate used in a support structure for a solar panel installation in a rural South African community. The plate is 100mm long, 50mm wide, and 5mm thick.

Step 1: Draw the plate using appropriate line weights. Object lines should be thick, and any construction lines should be thin.

Step 2: Add dimensions to indicate the length, width, and thickness of the plate. Use aligned dimensioning. The dimension lines should extend slightly beyond the extension lines and include arrowheads.

Step 3: Clearly label the dimensions with the correct units (mm). _

Example:_ "100", "50", "5".

Step 4: Add a general note indicating the material of the plate, such as "Material: Mild Steel".

Example 2: Creating a section view

Consider a cylindrical pipe with a hole drilled through its center. This pipe might be used in irrigation systems, vital in many parts of South Africa.

Step 1: Draw the front view of the pipe.

Step 2: Draw a cutting plane line through the center of the pipe, indicating where the section will be taken.

Step 3: Draw the section view, showing the cut surface of the pipe. Use appropriate hatching to indicate the material of the pipe (e.g., cast iron).

Step 4: Clearly label the section view and the cutting plane line. _Example_: "Section A-A".