By the end of this chapter, you will be able to:
Mastering these skills will help you produce clear, professional technical drawings that are essential for communicating ideas in the trade.
Orthographic projection drawings are fundamental in welding design and fabrication, providing precise, two-dimensional representations of three-dimensional objects. These drawings enable welding professionals to communicate exact dimensions, shapes, and assembly details clearly, reducing errors and enhancing productivity. Mastery of orthographic drawing techniques is essential for welders working on complex structures in industries such as construction, manufacturing, and shipbuilding within Kenya.
Orthographic projection is a cornerstone of technical drawing used extensively in welding to depict objects accurately and unambiguously. This section explores what orthographic drawings are, their importance, and how they differ from other drawing types commonly encountered in welding practice.
Orthographic drawing is a method of representing three-dimensional objects in two dimensions through multiple views, typically the front, top, and side. These views are projected perpendicularly onto planes, preserving true dimensions without distortion.
Multiple views: It commonly includes at least three views, front elevation, top plan, and side elevation, to capture all necessary details.
True scale representation: Dimensions in orthographic drawings are to scale, allowing measurements to be taken directly from the drawing.
Welding professionals encounter various drawing types; understanding the distinctions ensures correct interpretation and application.
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Create a free accountThis chapter covers the fundamentals of orthographic projection drawings, emphasizing their definition and importance while distinguishing them from isometric and perspective drawings. It explains the two main types of orthographic projections, first-angle and third-angle, detailing their specific conventions. The chapter explores the essential views used in orthographic drawings, including front, top, and side views, as well as additional sectional and auxiliary views. Students learn to develop accurate first-angle and third-angle orthographic drawings following established standards. Proper techniques for saving and printing orthographic drawings are also examined to ensure correct documentation. The creation of isometric drawings is introduced, focusing on selecting the isometric cursor, dimensioning, and printing these drawings. Finally, the chapter guides learners through creating 3D models using specialized workspaces and tools, covering modifications, rendering, and printing of 3D representations.
Type: Individual
| Tools & Equipment | Materials |
|---|---|
| Pencil (HB) | A4 plain paper |
| Eraser | Sample drawings booklet (orthographic, isometric, perspective) |
| Ruler 300 mm | |
| Set square 45° | |
| Protractor |
| S/N | Item | Quantity |
|---|---|---|
| 1 | A4 plain paper | 5 sheets per Candidate |
| 2 | Pencil (HB) | 1 per Candidate |
| 3 | Eraser | 1 per Candidate |
| 4 | Ruler 300 mm | 1 per Candidate |
| 5 | Set square 45° | 1 per Candidate |
| 6 | Protractor | 1 per Candidate |
| 7 | Sample drawings booklet (orthographic, isometric, perspective) | 1 per 5 Candidates |
| Items to be Evaluated | Marks Available | Marks Obtained | Comments |
|---|---|---|---|
| TASK 1: Adherence to safety and proper use of drawing tools | |||
| Wore appropriate PPE (e.g. dust coat if applicable) (Award 1 mark if worn correctly, 0 if not) | 1 | ||
| Handled drawing tools correctly and safely (Award 1 mark for correct handling, 0 if mishandled) | 1 | ||
| Maintained a clean and organized workspace during the task (Award 1 mark for good housekeeping, 0 if untidy) | 1 | ||
| Sub-Total | 3 | ||
| TASK 2: Demonstrated understanding of orthographic drawings fundamentals | |||
| Correctly identified orthographic drawings from sample booklet (Award 2 marks for correctly identifying all orthographic views, 0 otherwise) | 2 | ||
| Differentiated orthographic drawings from isometric and perspective drawings with explanation (Award up to 3 marks based on clarity and correctness of explanation) | 3 | ||
| Sub-Total | 5 | ||
| TASK 3: Prepared sketches and annotations | |||
| Drew orthographic projection sketches with correct views (front, top, side) (Award 1 mark per correct orthographic view drawn) | 3 | ||
| Included correct dimensioning for sketches (150 mm length x 100 mm width) (Award 2 marks if all dimensions are correct and clearly shown) | 2 | ||
| Sub-Total | 5 | ||
| TASK 4: Prepared a written explanation on importance of orthographic drawings | |||
| Explained importance of orthographic drawings in technical communication (Award 3 marks for clear, relevant explanation) | 3 | ||
| Sub-Total | 3 | ||
| TASK 5: Performed housekeeping | |||
| Left work area clean and tidy (Award 1 mark if area is clean and tools returned) | 1 | ||
| Sub-Total | 1 | ||
| PRODUCT CHECKLIST | |||
| Orthographic sketches with all three views correctly drawn and dimensioned (Award 5 marks if all views are accurate and dimensioned as per specification) | 5 | ||
| Written explanation correctly differentiating orthographic from isometric and perspective drawings (Award 5 marks for accurate and comprehensive explanation) | 5 | ||
| Sub-Total | 10 | ||
| GRAND TOTAL | 27 | ||
Type: Individual
| Tools & Equipment | Materials |
|---|---|
| Pencils (HB) | A4 plain drawing sheets |
| Eraser | |
| Set square (45° and 60°) | |
| Drawing compass | |
| Steel ruler 300 mm | |
| Protractor 180° |
| S/N | Item | Quantity |
|---|---|---|
| 1 | A4 plain drawing sheets | 2 sheets per Candidate |
| 2 | Pencils (HB) | 2 pcs per Candidate |
| 3 | Eraser | 1 pc per Candidate |
| 4 | Set square (45° and 60°) | 1 set per Candidate |
| 5 | Drawing compass | 1 pc per Candidate |
| 6 | Steel ruler 300 mm | 1 pc per Candidate |
| 7 | Protractor 180° | 1 pc per Candidate |
| Items to be Evaluated | Marks Available | Marks Obtained | Comments |
|---|---|---|---|
| TASK 1: Identification of Orthographic Projection Types | |||
| Wore appropriate PPE (overall, safety boots) (Award 1 mark each for wearing overall and safety boots) | 2 | ||
| Set up drawing tools correctly and prepared drawing sheets (Award 1 mark for correct tool setup and 1 mark for neat sheet preparation) | 2 | ||
| Correctly identified and labeled first-angle projection views for cube and cylinder (Award 2.5 marks each for cube and cylinder correctly identified and labeled) | 5 | ||
| Correctly identified and labeled third-angle projection views for cube and cylinder (Award 2.5 marks each for cube and cylinder correctly identified and labeled) | 5 | ||
| Used correct orthographic projection symbols (first-angle and third-angle) (Award 1 mark each for correct symbol drawing and placement) | 2 | ||
| Sub-Total | 16 | ||
| PRODUCT CHECKLIST | |||
| Orthographic drawings show correct dimensions: cube 150 mm sides, cylinder diameter 120 mm (Award 2 marks for cube dimensions and 2 marks for cylinder dimensions) | 4 | ||
| Projection views are correctly arranged according to projection type standards (Award 4 marks for correct arrangement for both first-angle and third-angle projections) | 4 | ||
| Labels and symbols are clear, accurate, and correctly placed (Award 4 marks for clarity and accuracy of labels and symbols) | 4 | ||
| Sub-Total | 12 | ||
| GRAND TOTAL | 28 | ||
At the start of this chapter we promised you would be able to:
Tick each one you can genuinely do.
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