How each part is made
Every part starts as a block on a grid of 10, 15 and 20 mm cells. One to three cuts make the steps, slots and notches; some parts get a 45 degree chamfer along one edge and a round hole drilled right through. Each view is worked out from that solid: an edge is dashed when something stands in front of it, and a visible line covers a hidden one on the same line. A missing-view question is only used when trying every arrangement of blocks on the drawing’s grid finds exactly one part that fits both given views.
A worked example
In set GA2222 (GCSE D&T, third angle) the part is 55 mm wide, 25 mm deep and 25 mm high: a slab 15 mm high across the back, and two posts at the front corners that rise to the full 25 mm with a 20 mm gap between them. The top of the slab runs behind the posts, so the front view shows it there as the dashed line H, 15 mm above the bottom; the height dimensions 15 and 10 give that height. Dimension A and the 10 next to it make the overall depth of 25, so A = 15. The overall height is left off: 15 + 10 = 25. Open set GA2222
What each level includes
Intro: third angle, plain blocks with steps and slots, and the names front, top and side view. GCSE D&T: third angle as the AQA specification asks, with chamfers and holes, and the names plan and end view. SA EGD: first and third angle mixed, as Paper 1 and Paper 2 use them, with front, top and left or right views. US engineering: third angle, with dimension figures that read from the bottom of the sheet. The first or third angle task always mixes both systems.
Questions
What is the difference between first angle and third angle projection?
Both draw the same views; only where they go changes. Third angle puts each view on the side you look from: the top view above the front view, the view from the right on its right. First angle puts each view on the far side: the top view below the front view, the view from the left on its right.
Which projection do GCSE D&T and EGD use?
The AQA GCSE Design and Technology specification asks for working drawings in 3rd angle orthographic. The South African EGD exam guidelines set Paper 1 (civil) in first angle and Paper 2 (mechanical) in third angle, unless a question says otherwise. US engineering courses use third angle.
What do the dashed lines on an orthographic drawing mean?
A dashed line is a hidden edge: a real edge of the part that is behind something in that view. Where a hidden edge and a visible edge fall on the same line, only the visible line is drawn. Thin chain lines (long and short dashes) are centre lines through holes.
How do you find a missing view?
Views line up: the front and top views share the width, the front and side views share the height, and the top and side views share the depth. Project every corner and edge across from the two views you have, decide which surfaces are in front, then draw hidden edges dashed.
What does the projection symbol show?
It is a cone drawn in two views: two circles and a side view. In the first angle symbol the small end of the cone points away from the circles; in the third angle symbol it points toward them. It tells the reader where each view has been placed.
How do you draw an isometric from three views?
Draw three axes: one vertical and two at 30 degrees to the horizontal. Measure widths, depths and heights along them at full length, box in the overall size, then cut away the steps and slots. Edges at other angles, like chamfers, are drawn by joining measured points. Hidden edges are usually left out.
Sources, checked October 25, 2026: AQA GCSE Design and Technology 8552 specification, version 1.2 (June 6, 2022), 3.3.5 Communication of design ideas; DBE Engineering Graphics and Design Grade 12 Examination Guidelines (2017): first and third angle papers and line types; Dell’Acqua and Mohammadi, Introduction to Engineering Drawing and Design (Engineering LibreTexts, CC BY 4.0): line types, multiview drawings, hidden edges; Wikipedia, Multiview orthographic projection: first and third angle and the projection symbol. Paid drawing standards (ISO 128, BS 8888, ASME Y14.3, SANS 10111) were not used.