brief introduction to engineering graphicskcbrown/s17_brief_intro_handouts.pdf · brief...
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Brief Introduction Lecture:F16 Handout Page 1
Brief Introduction
to Engineering GraphicsThe use of drawings to convey
information.
� Sketching
� freehand
� straight edge
� CAD drawings
� 2D drafting
� 3D model to 2D drawings
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� Orthographics◦ Multiviews
� Pictorials
◦ Isometric - a special type
of axonometric which uses
120 degree angles for axis.
◦ Obliques-front faces similar
to orthographic: 90° axis
� Perspectives
◦ Used in architecture, more
realistic but hard to use for
measuring.
Isometric Oblique
120°
90°
2
Different Graphical Representation of objects.On pg 27:
See Fig. 3
and Table 1
Brief Introduction Lecture:F16 Handout Page 2
Engineering Lettering
� Information that is hard to read is even harder to understand…use
GOOD ENGINEERING LETTERING
� Class standard is VERTICAL and UPPERCASE (except in the case of
*metric units) as shown on pg. 39 Fig. 21of graphics text
� Usually height of text is about 1/8” (3 mm) but don’t measure it…use
guidelines if provided.
Example of lettering expected for
all class assignments.
Fractions can vary from standard…don’t make too small
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*Note: 25.4 mm = 1 INCH
mm is millimeters, leave lowercase
10 mm = 1 centimeter
mm IS THE STANDARD METRIC UNIT
See pg. 30 Sec. 3 I inch
Examples of Lettering
Decent Lettering – spaced a
bit too close together
Same here – needs to keep letters VERTICAL!!!
FLOATING letters – needs to use
the guidelines
Incorrect fraction (too small).
POOR form (one shouldn’t
have top or bottom plus
NON-UNIFORM height.
Good Form plus correct way to do millimeters (case-sensitive)
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Brief Introduction Lecture:F16 Handout Page 3
Expectations of LetteringGood – spacing of letterings could be improved upon
Fair to Poor – form is fine but not uniform height –FLOATING letters.
Poor to Fail – Not vertical, not uniform height, poor spacing.
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- Linetypes -
� The type or appearance of a line depends on what it
is trying to represent.
� Be familiar with the different types of lines found in
Fig. 7 on pg. 29.
Solid/Continuous indicates a
visible surface/edge
Dashed indicates a hidden
surface/edge
Centerline indicates symmetry
� Each linetype has its own lineweight too.
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Radius of:
Centermark indicates center of circular feature. Extends past actual diameter Ø
of circle of or radius of arc.
22 mm
Started at 10 mm mark - due to manufacture of ruler
Brief Introduction Lecture:F16 Handout Page 4
- RULES and EXPECTATIONS -
� Use of straight edge is allowed.
� Lettering templates, circle templates, compasses
and other “drafting” equipment is not allowed.
� NEATNESS and ACCURACY do count!
� Even Lineweight (LWT)
� Sharp corners
� Gaps (or no gaps) in important areas
� Examples will be given showing both “good” and
“poor” work.
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- SKETCHING EXAMPLES -
� FAIR (B work)• Uneven LW
• Visible Lines need to be darker
• Poor dashes
� GOOD (A
work)
� POOR (D
work)• overall
neatness
• used straightedge (sort of)
� I suggest using a SHARP No. 2 pencil or a 0.7 mm HB lead mechanical pencil.
� Don’t forget the straight edge.
� Fig. 24 on page 70 shows examples of good totally freehand lines. You are allowed and expected to use a straight edge.
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Brief Introduction Lecture:F16 Handout Page 5
Examples
FAIR circle sketch – a bit too flatten bottom
See Methods for sketching circles
on page 73 for good circle
sketching technique.
Didn’t use straight edge
Circle form good –uneven lineweight (LWT)
UnevenLWT
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-More Examples-10
• Hidden Lines
should not be scaled
• Watch for
where gaps
should be
• Uneven linewt
• This is a better hidden line
form.
• Follow
directions.• Gaps should
be included
only when
needed.• Uneven linewt
• Poor hidden
line form, this is a stitch.
• Circle is poor
Brief Introduction Lecture:F16 Handout Page 6
- Decimal Inch and Metric Scale-
� Metric is millimeters
� 10 mm per centimeter
� 2.54 centimeter per inch
� Decimal Inch
� smallest unit is .02
inch
� 50 divisions within each inch
� 12 inches per foot
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ABBREVIATIONS USED IN GRADING – FOR REFERENCE
� LWT or LW for lineweight
� GEL for good engineering lettering
� ^ for gap needed (or not needed)
� NEAT for neatness
� ACC for accuracy
� WSS for where shape shows
� FFS from finished surface