2.2 Orthographic projection

• describe orthographic projection as used in drawing
• distinguish between first and third angle orthographic projections
• draw given pictorial views in first angle orthographic projection
• draw given pictorial views in third angle orthographic projection
• dimension views in orthographic projection
• appreciate the application of orthographic projection in real life

“How is orthographic projection used in drawing?”

“How are skills in orthographic projection applied in power mechanics?”

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1. Flat views with true sizes
   40 min · 1 practice tasks · quiz
   Project each face with lines of sight square to it, and see why one view cannot fix the depth.
2. Front, plan and end
   40 min · 1 practice tasks · quiz
   Name the three views of a 70 by 36 by 32 block and record the rectangle each one must contain.
3. First-angle placement
   40 min · 1 practice tasks · quiz
   Place the plan below the front and the left-end view on the right, and draw the first-angle symbol.
4. The plain block in first angle
   40 min · 1 practice tasks · quiz
   Draw the 70 by 36 by 32 block in first angle and transfer the 36 mm depth with dividers or a 45 degree mitre.
5. Third-angle placement
   40 min · 1 practice tasks · quiz
   Place the plan above the front and the left-end view on the left, and reverse the projection symbol.
6. The same block in third angle
   40 min · 1 practice tasks · quiz
   Redraw the 70 by 36 by 32 block with the plan above and the end view on the left, and match it to the symbol.
7. A step in first angle
   40 min · 1 practice tasks · quiz
   Draw a right-hand step, 24 mm long and 12 mm down, on the 70 mm block in first angle.
8. The same step in third angle
   40 min · 1 practice tasks · quiz
   Move the stepped views so the plan is above and the left-end view is on the left, without changing the step.
9. Dimension the step
   40 min · 1 practice tasks · quiz
   Add millimetre sizes to the third-angle step without closing a chain that is already fixed.
10. A hole, a diameter and the bay
    40 min · 1 practice tasks · quiz
    Draw a 60 by 40 by 30 pad in third angle with a 16 mm vertical hole, and dimension the circle where it is visible.