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°

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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