SME
Engineering Graphics & CAD
Orthographic and isometric projection
Use this for “Which of these three views is the top view, and why is the hole drawn dashed in the front view?”
Explore
Picture the part inside a glass box and look straight through one pane at a time.
What you see through the front, top and right panes are the three principal views.
Assumptions
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Each view looks straight at one face, so edges parallel to that face show their true length.
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US drawings use third-angle projection: the top view above the front, the right view to its right.
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The block: a 60 × 40 × 15 mm base, a 30 × 40 × 20 mm step on its left, a Ø12 mm hole through the base.
Topic check
See what you know: 5 questions on this topic
New questions each time. Pass to mark it complete.
More problem types
Isometric projection length
Use this for “A 50 mm edge runs along an isometric axis. How long is it on a true isometric projection?”
Line types on a drawing
Use this for “Which line on this drawing is a hidden line, and which is a center line?”
First-angle or third-angle projection
Use this for “The top view is drawn below the front view. Is this drawing first angle or third angle?”