ENGR150 Engineering Graphics Spring 2008 © Eric Smiley 2006 1 ENGR 150 Engineering Graphics Section Views Cutting Plane • Imaginary cutting plane • Reveals interior features • Direction of line-of-sight is important Hidden Lines • Section views reduce the number of hidden lines. • Therefore hidden lines are omitted from section views • Center lines are shown. Cutting Plane Lines • … show edge view of the cutting plane. • … have an arrow which indicates line- of-site. – arrow points away from the section view! • … take precedence over center lines in edge view. Section lines • … indicate surfaces cut by the cutting plane. • … are usually 45°. • … should not run parallel to visible lines. • Avoid text or dimensions within sectioned areas. • Cast iron is a general purpose symbol. Full-Section
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ENGR150 Engineering Graphics Spring 2008
© Eric Smiley 2006 1
ENGR 150Engineering Graphics
Section Views
Cutting Plane
• Imaginary cutting plane
• Reveals interior features
• Direction of line-of-sight is important
Hidden Lines
• Section views reduce the number of hidden lines.
• Therefore hidden lines are omitted from section views
• Center lines are
shown.
Cutting Plane Lines
• … show edge view of the cutting plane.
• … have an arrow
which indicates line-of-site.
– arrow points away from the section view!
• … take precedence
over center lines in edge view.
Section lines
• … indicate surfaces cut by the cutting plane.
• … are usually 45°.
• … should not run parallel to visible lines.
• Avoid text or dimensions within sectioned areas.
• Cast iron is a general purpose symbol.
Full-Section
ENGR150 Engineering Graphics Spring 2008
© Eric Smiley 2006 2
Half-Section Broken-out Section
Revolved Section Removed Section
Offset Section Ribs and lugs
• A thin flat feature used for support
• Adding section lines
would imply solidity.
• When cutting plane runs parallel through rib – do not section.
• Only applies when C.P. runs parallel.
ENGR150 Engineering Graphics Spring 2008
© Eric Smiley 2006 3
Standard Parts (Assembly)
• Standard parts (shafts, bolts, screws, nuts, rivets, keys, pins, bearings, and
gear teeth) are not sectioned.
• Only shown in
assembly drawings
Webs and Spokes
• Similar to ribs.
• Again – only applies when C.P. runs
parallel to web.
• Not sectioning spokes indicates the “non-continuity” around
circumference.
Alternate Sectioning: Webs & Ribs
• Sometimes no section lines would imply the absence of a feature.
• Alternate section lines are then used.
– Same direction
– Different spacing
Intersection of Cylinders
A. When a true projection creates a minor distortion a simplification is used. The true projection is replaced with a simple straight line projection.
B. Where the cutting plane intersects large features such as a large hole, the true projection is shown.
Foreshortening
• True orthographic projection sometimes yields a misimpression of objects.
– Example: Foreshortening of spokes should be avoided.
• Recommended practice is to rotate the spoke into the plane of the section view.
• The spoke is not sectioned as in conventional practice.
• The rear spoke projection is omitted for clarity.
Breaks
• Short break
• Long break
• Round solid
• Round hollow
• Rectangular solid
• Rectangular hollow
ENGR150 Engineering Graphics Spring 2008
© Eric Smiley 2006 4
Exercise: Sections Auxiliary Views
• Used to show true size and shape of inclined surfaces.
Creating Auxiliary Views Partial Auxiliary Views
Auxiliary Section
• Like a removed section.
• Only shows cross-
section.
Exercise
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