School of Technology

TECH 13580 - Engineering Graphics I

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A. Drafting Board - Soft wood, such as basswood. Only use one "working edge". Drafting board used at home, not required to bring to class.

B. T-Square - Two parts; head & blade. Must be square. Mount paper aligned with upper edge & draw against upper edge, never lower edge. 24" blade satisfactory for this course if purchased for work at home.

C. Compass - 6" bow compass satisfactory.  Use 2H lead and tilt as drawing. Set at desired radius via line on scrap paper, not stabbed into scale. Tilt, twirl while drawing. 3" bow compass or drop spring bow compass used for small circles. Ink pen attachment available Consider circle template.

D. Friction Dividers - Used to transfer measurements quickly. Must be tight and uniform point length.

E. Beam Extenders - Used to draw large circles. Beam compass and trammel points are used for very large circle layouts.

F. Triangles - Two types; 30-60 degree & 45 degree. Consider purchase of 8" 45 degree & 10" 30-60 degree. Place leg on T-square or Jacob's parallel ruling straightedge to draw with triangle. Triangles can be used together to draw 15 degree angle increments.

G. Protractor - Used to draw angles smaller than 15 degrees when triangles won't suffice.

H. Irregular ( French ) Curve - Available in many sizes and shapes to draw irregular curves. Align more points than drawn against at a time. Keep moving the curve. Any portion of the curve can be used.

I. Ames Lettering Guide - Used to establish height of guidelines for lettering.

J. Eraser - Use as soft eraser as available.

K. Art Gum - Cream colored block used to remove smudges, not to erase.

L. Drafting Tape - Used to hold down paper at corners. Not as sticky as masking.

M. India Ink - A waterproof ink used to ink a drawing, not Indian ink.

N. Drafting Media - Usually translucent as required for reproduction. 
    Vellum - Common material sometimes called tracing paper 
    Drafting Cloth - Called linen, actually cotton, an old-time material for high quality results. 
    Drafting Film - ( Mylar ) for high quality durable results, expensive, requires a plastic pencil.

O. Drafting Machine - A tool combining function of T-square, scale, and triangle. Be sure blades are set square.

P. Scales - Used to establish measurements, not to be used as a straightedge. Various shapes and types including the following : 

Mechanical Engineer's Scale - inch divided by 16 parts; an inch or portion of an inch represents an inch
( can be 3/4 size, 1/2 size 3/8 size or 1/4 size) 
Civil Engineer's Scale - inch divided by 10 parts; an inch to represent 10 feet or more (10, 20, 30, 40, 50) 
Architect's Scale - inch divided by 12 parts; an inch or a portion of an inch represents a foot ( 3, 1 1/2, 1, 3/4, 1/2, 3/8, 1/4, 3/16, 1/8, 3/32)
Metric Scale - designed according to metric system with meter as standard unit.  ( 1 meter = 39.37 inches or 1 inch = 25.4 mm)  Scales are: 1:1(mm), 1:20, 1:33 1/3, 1:40, 1:50, 1:80, and 1:100.

Study Scales Study Guide.

Q. Erasing Shield - Thin metal piece used to protect lines while erasing.

R. Pencils - Mixture of graphite and clay (kaolin ) ratio determines hardness.

Three Grades: 
    Hard = 9H - 4H 
    Medium = 3H - B 
    Soft = 3B - 7B

Consider 2H for most lines of finished ( darkened ) drawing, 6H for construction ( preliminary ) work, and 4H for center, hidden, & dimension lines. All finished lines are to be black. Avoid using too soft a lead, press harder. Also, consider metric lead and metric lead holders ( .3mm, .5mm, & .7mm ) to avoid sharpening so often.

A. Accuracy - The drawing must be at least within 1/16" of actual design size. CAD is much more accurate. Must conform to conventions to communicate for reader to accurately visualize design.

B. Speed - Learn the tricks. " Time is money. "

C. Legibility - Must communicate design.

D. Appearance / Neatness / Orderliness - Professional expectation.

A. Alphabet of Lines  

B. Paper Sizes - Letters used to signify size....

            Engineer's Standard             Architect's Standard 
A -                 8 1/2 x 11                                               9 x 12 
B -                 11 x 17                                                 12 x 18 
C -                 17 x 22                                                 18 x 24 
D -                 22 x 34                                                 24 x 36 
E -                 34 x 44                                                 36 x 48

Paper also available by rolls.

C. Lighting - Northern best coming from left of right-handed draftsperson

D. Eye Damage - Reported not to damage vision, but will tend to alert problem.

E. Drawing Horizontal Lines - Draw on upper edge of parallel or T-square away from the body ( left to right for right-handers ), tilt pencil at 60 degrees and rotate while drawing.

F. Drawing Vertical Lines - Drawn against triangle which is placed on Jacob's parallel ruling straightedge or on T-square. Hold with left hand, draw upward with right hand, and rotate pencil held at 60 degree angle. Avoid placing triangle backwards. 

G. Left-handers - Place triangle opposite fashion used by right-handers, still draw away from your body for mechanical drawing.

H. Attractive Work - Attitude & technique

1. Avoid sliding tools over pencil work, lift tools.

2. Clean tools and drawing board.

3. Sharpen pencil often, wipe off loose graphite.

4. Store sharpener in envelope.

5. Darken drawing last, working downward & across.

6. Store away items not in use.

7. Do not sharpen pencil or compass over board.

8. Draw with proper board covering such as Borco.

9. Place clean paper under palm of hand as support and protector when lettering.

10. Store and transport drawings in large ( B size ) envelope. Do not roll or fold drawings.