Technical Drawing and Workshop Planning
This domain tests your ability to read and produce working drawings, convert them into a cutting list, and plan the workshop so material flows without bottlenecks. Expect a projection question, a dimensioning question and a panel or timber take-off with waste.
Projection and views
- First-angle projection is the European standard: the object sits between observer and plane, so the view from the left is drawn on the right.
- The symbol settles it: the truncated cone. In first angle the pair of circles is on the opposite side to the taper; in third angle it is on the taper side.
- Line types: continuous thick = visible outline; dashed = hidden detail; chain thin = centre lines and pitch circles; continuous thin = dimensions, hatching, projection lines; chain thick at the ends = cutting plane.
- Sections are hatched at 45°; adjacent parts hatch in opposite directions; hidden lines are omitted from a section unless essential.
Dimensioning rules
- Dimensions go outside the outline, smallest nearest the view; never duplicate a dimension.
- Never dimension to a hidden line; dimension to visible edges or use a section.
- Prefixes: R for radius, the diameter symbol, square symbol for square section.
- Scales: 1:1 for details, 1:5 or 1:10 for furniture, 1:20 for room layouts, 2:1 for profiles.
Cutting list and take-off
Every line needs species or board type, thickness, width, length, quantity, grain direction and edge-banding note. Waste allowances: 15–25% for solid timber (defects, planing, snipe), 10–15% for panels. Saw kerf of 3–4 mm must be added between nested parts.
Workshop planning
- Set out from a face side and face edge, marked with the traditional pencil squiggle.
- Machine sequence: crosscut → rip → face-side flat → thickness → joint → assemble → finish. Doing it out of order means reworking.
- Allow about 1 m working space around a bench, and 3 m infeed and outfeed for a saw bench.
- Keep flow in a straight line from timber store to machine to assembly to finishing, with extraction routed overhead and racking away from walkways.
Worked example
A carcass take-off gives 14 parts totalling 9.80 m2. Add 12% waste: 9.80 × 1.12 = 10.98 m2. One sheet is 2.44 × 1.22 = 2.977 m2. Sheets required = 10.98 / 2.977 = 3.69, so four sheets by area. If the largest part is 2.35 m long and cannot be nested with others, the real answer may be five: always check nesting, not just area.
Traps that cost marks
Forgetting kerf and edge-banding thickness; omitting grain direction from the cutting list; mixing first- and third-angle symbols; dimensioning hidden lines; scaling a drawing and forgetting the ratio when writing the cutting list.
Annotate the drawing, then build the list from the drawing, not from memory.