The flashcards below were created by user
mdrake24
on FreezingBlue Flashcards.
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Full section
- Cutting plane passes throug entire object
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Offset Section
Cutting plane bent at 90 degress to show more detail on asymmetrical objects
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Half Section
- - Removes a quarter of the object
- - Reveals half of its internal details
- - All hidden lines ommitted
- - Not necessary to label cutting plane
- - Only half of view is cross sectioned
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Revolved Section
- Shows cross-section by rotating 90 degrees
- Remains on object
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Removed Section
- Shows cross section by rotating 90 degrees
- Moved to the side of object
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Broken out section
- No cutting plane required
- Does not modify rest of view
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Broken View
- Used for extremely large or long objects
- 2 break lines
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Detailed View
-Circle cut out showing more detail of an object
-Must have scale
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Sectioned Pictorials
Sketch of the object with portion missing
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Do NOT Hatch!!!
- Ribs
- Thin parts like gaskets
- Shafts or pins
- Screws or nuts
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Cast Iron and General Use
ANSI 31
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Steel
- "striped"
- ANSI 32
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Brass, Bronze, Copper
-ANSI 33
-"Road"
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Lead, Zinc, Magnesium
-ANSI 37
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Crest
Peak or prominent point of a thread
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Root
Bottom point at which sides of a thread meet
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Flank
Thread surface that connects a crest and a root
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Angle
Degrees between two flanks
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Pitch
Distance between 2 adjacent crests or 2 adjacent roots
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Thread length
Length of a threaded portion of a shaft
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Shank
Unthreaded portion between head and threads
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Thread symbols
Detailed, schematic, simplified
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Knurl
Pattern cut into cylindrical parts to improve gripping
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Counterdrilled
CDRILL or CD
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What is the standard measurement of an engineers's scale?
Inches
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What is the standard measurement of a metric scale?
Millimeter
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How does an architect's scale work?
Number on left of equal sign is specified by some fraction of an inch, number on the right is ALWAYS 1'-0"
Ex. 1/2 = 1'0"
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Tolerance
-Range of acceptable values for a particular dimension
-The smaller the tolerance, the higher the cost of manufacturing
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General Tolerance
-Applies to all dimensions of a drawing
-Often found in title block
-Normally in bilateral form
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Limit form - Tolerance
Has max value over min value
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Unilateral form - Tolerances
Has base value, then to the right of it has the maximum added above mimimum added
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Bilateral form - Tolerances
Base diameter, then to the right it has +/- a number
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Linear Fit Tolerances
How tight or how loose moving and sliding parts wll fit
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Hole tolerance
LPH - SPH
- Determines cost of hole
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Shaft Tolerance
LPS - SPS
- Determines cost of shaft
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Allowance
SPH - LPS
-Tightest fit between two moving parts
-Does not affect cost of parts
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Maximum Clearance
LPH - SPS
-Loosest fit between parts
-Does not affect cost of parts
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Clearance Fit
Shaft is always smaller than hole
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Line fit
Shaft is either smaller or equal to hole
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Transition fit
-Shaft could be larger or smaller than hole
-Cheapest way to manufacture part
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Which fit is the cheapest to manufacture a part?
Transition fit
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Interference fit
-"Force fit"
-shaft always larger than hole
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Geometric tolerances
-Controls level of error of shape not size
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Dimensioning
Always in real world units
Do not put units by numbers
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Styles for dimensioning
- Unidirectional: dimensions face same direction
- Alligned: dimensions parallel to lines
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Dimension spacing
- First row: 3 letter heights away (3/8")
- Successive rows: 2 lettee heights away (1/4")
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Dimensioning Cylinders
Place diameter where it appears at a rectangle
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Bolt circle
When feature has repetitive holes in circular pattern
BC
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Repetitive features
Ex. .75 DIA - 4 HOLES
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Horizontal projection plane
-Top view
-Depth and width
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Frontal projection plane
-Front view
-Height and width
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Profile projection plane
-Side view
-Height and depth
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Which dimensions on an orthographic projection project directly?
Height and width
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What is the difference between pictorials and orthographic projections?
Orthographic projections use 2-D views to represent an object. Projection pictorials show all three directions of space in one picture
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Parallel projections
Any lines that are parallel in the object are parallel in views
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Perspective projections
Reproduce the effect that distant objects appear smaller than nearer objects. Lines which are parallel in nature converge towards a single point.
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Types of axonometric projections
- Isometric
- Dimetric
- Trimetric
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Isometric projection
- -All three angles equal 120 degrees
- -H, W, and D are true size along isometric axes
- -Angles must be located by coordinates
- -Circles appear as ellipses on all surfaces
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Dimetric projection
2 angles are equal
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Trimetric
All 3 angles are different
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Oblique projection
Most descriptive face of object is projected parallel to projection plane, thus appearing true size
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Cavalier oblique
- -Front view true shape and size
- -Receding axis angle normally 30, 45, 60 degrees
- -Depth dimension true size
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Cabinet oblique
- -Front view true shape and size
- -Receding axis angle normally 30, 45, 60 degrees
- -Depth dimension HALF size
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General oblique
- -Front view true shape and size
- -Receding axis angle normally 30, 45, 60 degrees
- -Depth dimension is BETWEEN full and half size
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GRID Command
F7
Just a visual aid, does not print
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SNAP Command
F9
Allows you to specify precise coordinates when using the mouse
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ORTHO Command
Allows you to only draw in the vertical or horizontal direction
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DDEDIT Command
Click on a text or dimension to be edited/changed
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BHATCH command
Crosshatching
Area must be closed
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How many views are required to illustrate an object?
- -Depends on the object
- -The minimum necessary to adequately show the object's geometry
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What is the thickest line drawn in an orthographic drawing?
Visible line
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Which view should be the most descriptive view?
Front view
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Which dimension should be minimized in orthographic views?
Depth
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What are drawing methods used to provide a clearer understanding of an object, even if orthographic rules are violated?
Conventional practices
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Which type of sketch is not a pictorial?
Multi-view
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What types of projections are not parallel projections?
Perspectives
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In what type of oblique drawing is depth represented true size?
Cavalier
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Auxiliary view
Used to represent the true size and shape of objects with sloping surfaces
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In English thread notes, what represents the fit
- 1 for loose
- 2 for regular
- 3 tight
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In English thread notes, what represents if the thread is internal or external?
- A is external
- B is internal
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In metric thread notes, what represents the tolerance?
Numbers ranging from 3-9. The larger the number, the larger the tolerance.
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In metric thread notes, what represents the fit?
- Letters.
- E - loose fit
- G - regular fit
- H - tight fit
- Lowercase letters mean external
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In metric thread notes, what represents the thread length?
- S - short
- N - normal
- L - long
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T or F: The force on a truss link is called an axial force
True
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How do you calculate the number of joints in a 2-D truss?
L = 2 • J - 3
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How do you calculate the number of joints in a 3-D truss?
L = 3 • J - 6
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What are allowable loads (working loads)?
Forces to which the links can be safely subjected.
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What are the two principle modes of failure?
Failure by separation and failure by deflection.
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True or False. Zero-force members cannot improve the strength of a truss
False
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How do you calculate arc length?
S=R•radian angle
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How do you find zero force truss members.
If a joint connects only two truss members and no support reaction or external force is applied to the joint
If a joint connects only three members and two of the members are co-linear, and no support or external force is applied, then the non co-linear member is a Zero force member
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In which views will circles appear as ellipses for all views?
Axonometric projections
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What determines the diameter of the spotface for a spotface hole?
Left to the disgression of the machinist
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In what type of sections can you show hidden lines?
Broken out sections
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How do you calculate a safe loads?
- External load Largest tensile
- Force
- --------------= --------------
- Max allowable Tensile External load strength
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How do you calculate the factor of safety?
- Failure level Strength
- ------------- = --------------
- actual Internal Level member force
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T or F: The factor of safety is the most conservative value?
True
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When calculating internal forces, what do we assume?
The the bars are in tension. Therefore, the arrows are drawn going away from joint
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