Fundamentals of Technical Drawing — CSEC Technical Drawing
This topic covers the equipment, line types, lettering and scales that form the foundation of all technical drawing.
Drawing equipment
- Drawing board and T-square — the T-square slides along the board edge to draw accurate horizontal lines and to support the set squares.
- Set squares — the 45° and the 30°/60° set squares draw vertical and inclined lines (30°, 45°, 60°).
- Compass and dividers — for circles, arcs and transferring/dividing measurements.
- Protractor — for measuring and setting out angles.
- Pencils — harder grades (e.g. 2H) for fine, light construction lines; softer grades (HB) for outlining and lettering.
Types of line
| Line | Use |
|---|---|
| Continuous thick | visible outlines and edges |
| Short dashes | hidden detail |
| Thin chain (long dash–dot) | centre lines, lines of symmetry |
| Thin continuous | dimension and projection lines |
Using the correct line type and thickness makes drawings clear and standard.
Lettering
Lettering should be clear, upright (or slanted) and consistent in height, drawn freehand or with a stencil, so notes and dimensions are easy to read.
Scales
A scale is the ratio of the drawing size to the real size:
- 1:1 — full size.
- 1:2, 1:5, 1:50, 1:100 — reductions (drawing smaller than the object).
- 2:1, 5:1 — enlargements (drawing larger than the object).
Paper sizes
The A series halves in area each step: A0 → A1 → A2 → A3 → A4, so A1 is larger than A4.
Exam tips
- Match each line type to its use (thick = visible, dashes = hidden, chain = centre).
- Know that 1:2 is a reduction (half size) and 2:1 is an enlargement.
- A smaller A-number means a larger sheet.
- Use 2H for light construction lines and softer pencils for outlining.