Engr 123 Orthographic Projections

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Engr 123 Orthographic Projections
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Lines Types andOrder of Precedence
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0.7 mm
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0.5 mm
0.5 mm
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Hidden Lines

• Hidden features are represented in multiview
  drawing with hidden lines.
• Dashed lines are used to represent hidden
  features
• The length of the dash can vary based on drawing
  size.
• Drawing Conventions for Hidden Lines are shown on
  the next slide.

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From Fundamentals of Graphic Communication, 5
ed., Bertoline.
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From Fundamentals of Graphic Communication, 5
ed., Bertoline.
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Centerlines

• Centerlines are used as the axes for symmetrical
  parts such as cylinders, drilled holes, bolt
  circles, and paths of motion.
• Centerlines are represented by alternating long
  and short dashes.
• The length of the dashes may vary based on the
  size of the drawing.
• Drawing Conventions for Centerlines are shown on
  the next slide.

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Drawing Conventions for Centerlines

• Center lines should start and end with long
  dashes.
• Center lines should intersect by crossing the
  short dashes.

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Drawing Conventions for Centerlines

• Center lines should extend a short distance
  beyond the object or feature.

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Drawing Conventions for Centerlines

• Center lines may be connected within a single
  view to show that two or more features lie in the
  same plane.
• Center lines should not extend in between views .
  

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Centerline Drawing Conventions
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Centerlines Bolt Circle
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Centerlines Path of Motion
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Putting it all together

• Choose the front view.
• Determine the number of required views.
• Identify the scale.
• Draw visible lines for the front view.
• Project the feature to draw the top view.
• Project the features from the top view to a mitre
  line to draw the right view.
• Draw the hidden lines.
• Draw the center lines and center marks.

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