Technical drawing, planning and project work
This domain tests drawing interpretation, orthographic projection, dimensioning, scale and the planning needed to make a project. Expect questions on first-angle and third-angle views, line conventions, cutting lists, allowances, sequence and quality checks.
Core rules
- In first-angle projection the object sits between the observer and the plane: the view from the front is placed above the plan, and the view from the left is placed on the right. In third-angle projection the plane sits between observer and object, and views are placed on the same side as the observer.
- Use continuous thick lines for visible outlines, dashed lines for hidden detail, chain lines for centre lines, and thin lines for dimension and projection lines.
- Dimension from a datum, avoid duplicated dimensions, and do not scale a drawing when a dimension is given.
- A plan should list operations in a safe sequence, tools, materials, time and quality checks. A cutting list should include material, quantity, finished size and allowance for saw cuts and machining.
Worked example
A component is drawn at a scale of 1:5 and measures 42 mm on the drawing. Actual length = 42 x 5 = 210 mm. If a 3 mm machining allowance is needed on the end, the cutting length = 210 + 3 = 213 mm. Reason: the scale converts drawing length to real length, and the allowance must be added before cutting because the finished part must still be 210 mm after machining. A cutting list entry would read: mild steel, 1 off, 213 mm cut length, 210 mm finished length.
Traps that cost marks
- Mixing first-angle and third-angle view placement.
- Measuring a scaled drawing instead of reading the stated dimension.
- Forgetting saw-cut or machining allowance.
- Planning operations in an unsafe or impossible order.
- Omitting a final inspection step from the project plan.