Drawing and Design: notes

Drawing basics

• Line types: thick continuous lines show outlines, thin continuous lines show dimensions, dashed lines show hidden detail, and chain lines (long and short dashes) show centre lines.
• Orthographic projection: shows an object in separate views (front, plan, end). In first angle projection the plan sits below the front view. In third angle projection the plan sits above it.
• Pictorial drawing: isometric drawings use 30 degree angles; oblique drawings show the front face true shape with depth lines at 45 degrees.
• Dimensioning: give each size once, in millimetres, outside the shape where possible.
• Scale: 1:2 means the drawing is half the real size; 2:1 means double.

Sectional views

• Section: a cut through an object to show inner detail. Cut surfaces are hatched with thin lines at 45 degrees.

The design process

1. Problem: state what is needed, for example a toolbox for a school workshop.
2. Investigation: find out who uses it, what size it must be and what it must carry.
3. Ideas: sketch several solutions.
4. Choose and develop: pick the best idea and make a working drawing.
5. Make: use a cutting list (a table of every part, its material and size).
6. Evaluate: test the product against the needs and note improvements.