Engineering Drawing and Computer-Aided Drafting Practice
What this domain tests
Engineering Drawing and Computer-Aided Drafting Practice tests the transfer of drawing convention into CAD: coordinates, layers, dimensions, blocks, 3D modelling and plotting.
Core rules
- Set units and drawing limits first; model full size, then plot at a scale. Never scale the geometry to suit the paper.
- Coordinates: absolute (x,y); relative (@dx,dy); polar (@distance<angle). Angles are measured anticlockwise from the positive X axis.
- Use layers for line type, colour and purpose; keep dimensions on a dedicated layer. Draw on object layers, not on layer 0.
- Blocks group repeated symbols; attributes hold text such as tag numbers. Parametric constraints (coincident, parallel, dimension) let geometry update predictably.
- Dimension styles follow BS 8888/ISO 129: arrow size, text height, extension offset and precision should match the drawing standard.
- 3D: wireframe, surface and solid modelling; solids carry mass properties. Export neutral formats such as STEP or DXF for exchange.
- Plotting: model space versus paper space, viewport scale, line-weight display.
Worked example
From point (20, 10), enter @50<30. The displacement is Δx = 50 cos 30° = 43.30 and Δy = 50 sin 30° = 25.00. The new point is (63.30, 35.00). If the drawing is later plotted at 1:2, the dimension text still reads 50, because the line is modelled full size and scaled only at output.
Traps
Typing absolute coordinates where relative is intended; leaving every entity on layer 0; exploding dimensions so they no longer update; drawing at paper size; overriding object snaps and picking the wrong point; confusing model-space and paper-space scales; ignoring units.