Work each original question before you open its answer. They cover the lessons in pictorial representations.
Questions
1. In an isometric drawing, at what angle to the horizontal are the two receding axes drawn, and what is the third axis?
Answer
30° above the horizontal. The third axis is vertical, so the three axes are 120° apart.
2. A picture shows a box whose parallel top edges meet at a point in the distance. Is it isometric or perspective?
Answer
Perspective. Isometric keeps parallel edges parallel; converging edges mean a vanishing point.
3. An isometric drawing of a box shows 45 mm along the left axis, 30 mm along the right axis and 25 mm vertically. State the real width, depth and height, in the order left axis, right axis, vertical.
Answer
45 mm, 30 mm and 25 mm. Lengths along the three axes are drawn at true size.
4. A student measures a slanting chamfer edge in an isometric drawing with a ruler and reads 18 mm. Why is this unreliable?
Answer
Only lines along the three axes, or parallel to them, keep true length. A slanting edge is not on an axis, so its drawn length is not its real length.
5. A cabinet oblique drawing has receding edges drawn 14 mm long. What is the real depth?
Answer
14 × 2 = 28 mm, since cabinet draws depth at half length.
6. A cavalier oblique drawing of a block has a front face 70 × 40 and receding edges drawn 25 mm long. Give the real width, height and depth.
Answer
Width 70 mm and height 40 mm from the true-shape front face. Depth 25 mm, since cavalier uses full length.
7. A circular hole is on the front face of a block drawn in oblique. What shape does it take in the drawing?
Answer
A circle. The front face is drawn parallel to the paper in true shape, so circles on it stay circles.
8. A block is 50 mm wide, 30 mm high and 40 mm deep. Give the receding edge length if it is drawn in (a) cavalier and (b) cabinet oblique.
Answer
(a) Cavalier: 40 mm. (b) Cabinet: 40 ÷ 2 = 20 mm.
If you got these wrong
- Questions 1 to 4: reread telling isometric from perspective views.
- Questions 5 to 8: reread reading oblique drawings and true lengths.
Next, look inside objects with sections and spatial reasoning.
If you want a teacher to set new pictorial questions and check your working, see online one-to-one Engineering Drawing tuition.