Work with Machines and Materials | Class 9 Skill Education Notes

Making Technical Drawings

Technical drawings are detailed visual representations that include dimensions and material specifications, enabling precise communication among designers, engineers, and fabricators. They allow identical replication of products, ensuring consistency and quality.

Technical drawing is a specialized language with rules and symbols. Commonly used lines include visible lines (showing edges), hidden lines (indicating obscured edges), centre lines (marking symmetry), and dimension and extension lines (showing measurements).

Symbols are used in various fields, such as plumbing, civil engineering, and electrical circuits, to represent components like pipelines, basins, toilets, buildings, rivers, roads, and electric lines.

To represent three-dimensional objects on two-dimensional surfaces, projection techniques are used, showing front, top, and side views. For example, a table is represented by its front, top, and side views to convey complete shape and size.

In construction, the top view is called a Plan, and the front view is called Elevation. Technical drawings for electric circuits are called circuit diagrams, plumbing layouts are plumbing diagrams, and garment outlines are patterns.

Since actual dimensions are often too large for paper, drawings use scales (e.g., 1:100 means 1 unit on paper equals 100 units in reality). Understanding scale is crucial for interpreting and creating drawings.

Students are encouraged to read and create technical drawings, interpret dimensions, and apply scales accurately.

This skill is essential for designing, manufacturing, and quality control in all vocations related to machines and materials.

📊 Diagram: Figure 5.4: Commonly used lines and symbols in technical drawing; Figure 5.5: Projections of different objects; Figure 5.6: Technical drawing in construction; Figure 5.7: Technical drawings of electric circuits, plumbing systems and dress pattern; Figures 5.8 and 5.9: Technical drawings of a table and plan of a house; Figure 5.10: 3D drawing of a stool

🧪 Activity: Tasks: Read and answer questions on technical drawings of a table and house plan; create a technical drawing of a stool using given dimensions and scale.

🔗 Connection: Prepares students for selecting vocations related to machines and materials.