Transcript Engineering Graphics H193

Technical Communications
1
Objectives
• Understanding graphics as a communication tool
• Technical sketching
• Projections
– Orthographic
– Pictorial
• Sketching hints
• Lettering
2
How Would You Describe This?
• In teams of two, describe using only words
• How effective is this approach?
3
Three Basic Types of Technical Drawings
• Freehand sketches
• Instrument drawings
• Computer drawings and models
4
Introduction to Projections
• Present 3-D objects with 2-D media
• Two Basic Categories
Orthographic
Pictorial
5
Projections: Four Basic Types
Orthographic
Projections
Axonometric
Pictorials
Oblique
Perspective6
Orthographic Projections
• Collection of 2D drawings
• Accurately represent object
• Technical Graphics
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Orthographic Projection
8
Defining the Six
Principal Views
or
Orthographic Views
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Which Views to Present?
• General Guidelines
– Pick a Front View that is most descriptive of
object
– Normally the longest dimension is chosen as
the width (or depth)
– Most common combination of views is to use:
Front, Top, and Side View
– Views other than the Principal Views are called
Auxiliary Views
10
11
Conventional Orthographic Views
Width
Top View
Front View
Depth
Right
Side
View
Height
12
Hidden and Center Lines in Orthographic
Projections
•
Object Lines – represent visible features for an
object
•
Hidden Lines – represent features that cannot
be seen in the current view
•
Centerlines – represent symmetry and mark the
center of circles, the axes of cylinders, and the
axes of symmetrical parts, such as bolts
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For Example:
1. Visible
2. Hidden
3. Center
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Creating the Orthographic Projection Sketch
• Front View
• Right Side
View
• Top View
15
Step 1 – Lightly Block Three Views
Use very
light lines
for drawing
in the
construction
lines
16
Step 2 – Lightly Block Major Features
• Holes
• Arcs
• Cutouts
Use very light
lines for
drawing in the
construction
lines
17
Step 3 – Refine and Locate Features
in All Views
Use very
light lines for
drawing in
the
construction
lines
18
Step 4 – Add Final Lines
Use very
light lines for
drawing in
the
construction
lines
19
Completed Sketch
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Add Another View
• Sketch the left side view of the object
• Compare your view with the others at your table
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Add Another View
• Does yours look something like this?
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Lettering Notes
• Lettering Guidelines – Technical Graphics:
Chapter 1
• Lettering Styles
– Shape of Letters
– Order of drawing lines
• Character Uniformity
• Spacing
23
Lettering – Vertical Gothic Font
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Sketching Tips: General
• Relax and draw in a direction comfortable to you
• Mark end points of the lines to be sketched and
draw between them
• Draw long lines as a series of short ones
• Use grid paper when available
• Follow sketching and text conventions
• Do NOT use a straight edge to draw lines!
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Sketching Tips: Construction Lines
• Use construction lines
• Begin by drawing bounding boxes with
construction lines
• Make construction lines much lighter and thinner
than finished lines
• Identify the major features and overall
dimensions
• Leave construction lines on the sketch
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Sketching Tips: Miscellaneous
• Do not shade the drawing – this is not pencil
sketching
• Title information is required
• Keep views aligned (very important)
• Include centerlines on isometrics
• Avoid labels on the sketch
• Draw neat circles – change page orientation if
needed
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Creating Production Drawings
Goals
• Understand production drawings, including detail
drawings and assembly drawings
Reference
• Technical Graphics
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Mechanical Production Drawings
• Production drawings (sometimes called Working
drawings) are the complete set of drawings
specifying the manufacture and assembly of a
product.
• Generally consists of multiple drawings, on
multiple sheets. A title block appears on each
sheet.
• May contain written instructions called
specifications.
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Set of Production Drawings
A set of Production Drawings has three main parts:
1. Detail drawings of each non-standard part,
usually one part per "sheet".
2. An assembly drawing (or subassembly
drawings) showing all parts in a single drawing.
3. A bill of materials (BOM). This is essentially a
parts list.
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Reading Production Drawings
• Our first goal is to learn how to read a set of
production or working drawings.
• Example: simple fingernail clipper
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Example 1 – Assembly Drawing
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Full Section View
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Detailed Part Drawing: Rivet
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Detailed Part Drawing: Bottom Clipper
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Assembly Drawing
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Example 2 – Butterfly Valve
Isometric
Halfsectioned
isometric
Exploded
AU 2006
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Individual Part Drawings