Eng Graphics - chapters 1-6

What is design?

A strategic approach to problem solving

A sketch

Quick freehand drawing thats purpose is to communicate a design

How do you communicate your completed design that

needs to be manufactured or used as a legal document?

Create a technical/engineering drawing

what is a technical engineering drawing?

a set of drawings that communicate an idea, design, schematic, or model that fully and clearly define requirements for an engineered part or system

• provide tolerancing, annotations, parts lists, etc. essential for manufacturing and quality control

What is the variation within each field of engineering’s drawings?

• Electrical engineers draw circut schematics and circut board layouts

• civil engineers draw plans for bridges and road layouts

• Mechanical engineers draw parts and assemblies that need to be manufac

what is CAD’s brief history?

made in 1982 by John Walker

Solidworks brief history?

made in 1993 by Jon Hirschtick (first with 3D modeling)

What are the four key stages of the engineering design process

What are the two main organizations that set blueprint standards?

ASME and ISO(International Organization for Standardization)

Technical drawings in the past were blue T/F?

True

What are the Drawing aspects of blueprints?

what are the Engineering Drawing Format and Contents?

Zoning: The letter-number combinations allow you to indicate a specific location on an engineering drawing

Title block

A) Company name and address
B) Drawing title
C) Drawing number
D) Sheet revision (May be omitted when revision history block is included)
E) Contains sub blocks (DRAFTER, CHECKER, & ENGINEER)
F) Approval of design when different from source preparing drawing (nescicary when contractor/subcontractor condition exists)
G) Approval for activity other than described in E & F
H) scale
I) DAI (Design activity identification
J) Drawing Size
K) Actual/Estimated weight of item
L) Sheet #

Revision history block

A) Zone location of revision
B) Revision Letter or #
C) Brief description of change
D) Revision date (year-month-day)
E) Initials of approval

What is an orthographic projection?

An orthographic projection is a 2-D representation of a 3D object

Which one is the orthographic projection?

How many principal views are there?

6

Projection Lines are viewed at an _______ distance

infinate

Every object requires 6 orthographic projections to accuratley depict an object T/F?

False, the only needed projections are the ones that present new/useful information

what are the drafting standards for

- sheet formats
- Line conventions and lettering
- multiview an sectional view drawings
- dimensioning and tolorencing

1) ASME Y14.1-2005
2) ASME Y14.2M-1992
3) ASME Y14.3M-1994
4) ASME Y14.5M-1994

Key volume formulas to remember
a) extruded volume = base*height
b) Sphere (4/3)(pi)(r³)
c) Cone (1/3)(pi)(r²)(h)
d) 2(pi²)(r²)(R)

What are all the line types in orthographic projections?

• Visible line

• Hidden

• Center

• Phantom

• Break

• Section

What are section lines used for?

Show cut lines and show the type of material

What are visible lines used for? ——————

represent visible edges and boundaries (0.5-0.6 mm)

What are hidden lines used for? - - - - - - - -

Reprsent edges and boundaries that cannot be seen, dashed and medium thick (0.35 - 0.45 mm)

What are center lines used for? —— — ——

Represent axes of symmetry and paths of motion, long and short dashes (about 0.3mm)

What are Phantom lines used for? —— — — ——

Used to indicate imaginary features such as 1) alternate positions of moving parts, 2) adjacent positions of related parts
lines are about 0.3mm

What are break lines used for?

show imaginary breaks in objects, made up of a series of connecting arcs ~ continuous and thick (0.5 - 0.6mm)

what are the Rules for the hidden lines?

1)length of the hidden line dashes may vary as the size of the drawing changes
2) hidden lines should always begin or end with a dash except when parallel to a visible hidden line —-| - - - -
3) dashes should join at corners

what are the Rules for the Center lines?

1) must start and end with long dashes
2) Center lines should intersect by either long or short dashes
3) lines should extend a short distance beyond the object/feature
4) can be connected within a single view to show that the features lie within the same plane

what are the Rules for the Phantom lines?

1) Phantom lines should start and end with a long dash

what are the Rules for the Break lines?

1) if the distance is short than a series of connecting arcs ~
2) if the distance is long then long thin straight line with jog is used

If two lines ocour in the same place then the less important line is omitted

• cutting plane line (most important)

• Visible line

• Hidden line

• Centerline (least)

United States = 3rd angle projection

Europe = 1st angle projection

Diference between 1st and 3rd angle projections

when converting from one to another the top & bottom and left & right are switched

Tolerance and projection blocks

What are the line types used in dimensioning?

• Dimension lines

• Extension lines

• Leader lines

What are Dimension Lines used for?

indicates the extent of a dimension

What are Extension Lines used for?

indicates what feature is being dimensioned

What are Leader Lines used for?

adding notes on the blueprints

What are the rules for leader lines?

• Crossing leaders

• Long leaders

• leaders that are parallel to an adjacent dimension

• small angles between the leads and the terminating surface

Arrowheads

• if space is limmited between the extension lines then they may be drawn outside

Dimensioning circulear items

Dimensioning a blind hole

A complete sphere is dimensioned by its diameter and an incomplete sphere by its radius.

Rules for Dimensioning

1) Do not dimension inside an object unless clarity is gained
2) Dimension text should be horizontal to bottom of drawing
3) dimension text should not cover any lines or information
4) extension lines can cross other extension lines
5) dimension lines should not repeat information

What is the prefered datum?

Dimensioning repetitive features

Spotfaced Hole

Countnter Sink hole

Counterbored Holes

Chamfers (safety and to improve engagement of mating parts)

what are the pictoral types?

• Axonometric (most common: Isometric)

• Oblique (most common: Cabinet oblique)

• Perspective

3 Axonometric Projections

• Isometric

• Dimetric

• Trimetric

Axonometric - Isometric

Axonometric - Dimetric

Axonometric - Trimetric

Axonometric projections have ____

• projector that are perpendiculear to the projection plane and parallel to each other

• Principal edges 90 degrees appart on the physical objec

3 Oblique projections

• cavalier

• cabinet

• general

Oblique projections are ______

not perpendiculear to the projection plane but are parallel to each other

Cavalier Oblique

Cabinet Oblique

General Oblique

3 Perspective projections

• one-point

• two-point

• three-point

Perspective - one-point

Perspective - two-point

Perspective - three-point

Isometric Pictoral

Sectioning

Part is cut using an imaginary cutting plane the unwanted part is mentaly discarded

2 Cutting plane lines

• Phantom (long distances)

• hidden (short distances)

In section views the arrows represent ________

the portion being used

Section lines are used to indicate ___________

the cutting planes material

Cast Iron

Steel

Brass, Bronze, Copper

Rubber, Plastic, electrical Insulation

Zinc, Lead

Concrete

Rules for Sectioning

1) Section line area is always bounded by a visible outline
2) Section lines in all areas are parallel (opposite lines indicate different part)
3) all the visible edges behind the cutting plane line should be shown
4)Hidden features should be omitted (except when threads or broken out sections)

6 types of sections

• Full

• half

• offset

• broken-out

• Revolved (aligned section)

• Removed section (detailed section)

Full section

• cutting plane line passes fully through object

• commonly used to avoid having to dimension hidden lines

Half Section

• used mainly for symetric sections

• one half is sectioned

• centerline is used to sepperate halves

Offset section

bending cutting plane to show features on diferent planes

Aligned section

cutting plane is bent so it passes through all features

Rib and Web sections

• to avoid false impression of thickness (ribs are not sectioned)

• if the cutting plane passes crosswise through the rib or web we include their section lines

Broken sections

• hidden lines are shown in the non-sectioned area of a broken section

Removed section

a removed section is not in direct projection of the view containing the cutting plane

Revolved section

the cross sectional shape of an object may be shown in the longitudinal view by means of a revolved section

Non-sectioned parts

• nuts

• bolts

• rivets

• shafts

• screws

for extremely thin parts less than 4mm thickness the parts should be shown __________________________

in solid black without section lines
ex:
- sheet metal
- washers
- gaskets