ME 123

Pataasin ang iyong marka sa homework at exams ngayon gamit ang Quizwiz!

in first angle, you _______ the object

"roll"

in third angle, you _________ the object

"unfold"

when going from an oblique pictorial to a multi-view, what does a scale of .7071 mean?

1 diagonal on the oblique = 2 units on the pictorial (only for receding axis)

what is the order of line precedence?

1) visible 2) hidden 3) center

how do you select the front view of a multi-view?

1. best shape 2. best operating position 3. least hidden lines 4. longest dimension

what is the scale going back in cabinet oblique projections?

1/2 scale

types of CAD

2D Wireframe Surface modeling Solid modeling

user-defined features

2D sketches that are pulled through space

what angles can oblique projections have?

30, 45, or 60

additive manufacturing

3D printing; software generates thin slices of a model and system creates and fuses them together

who makes drawing standards

ASME

How can you tell a pictorial is a perspective?

All parallel lines converge

Which 2 kinds of projection are orthographic?

Axonometric and multi-views

How can you tell if a pictorial is an axonometric or not?

Axonometric if 3 mutually perpendicular planes have a horizontal that creates two 30 degree angles or if all ellipses have the same amount of foreshortening or "squishiness"

What are three negative features of wireframes?

Can't render Ambiguous No volume information, which limits analysis capabilities

scale

DRAWING = OBJECT or DO!

True or false: Centerlines take precedent over hidden lines in multi-view drawings

False

True or false: Isometric axes all have different foreshortening factors

False

True or false: The receding axis of an oblique must be drawn at a 45-degree angle

False

Are pictorials more or less ambiguous than multi-views?

More

Can you determine when edges are hidden from a wireframe?

No

In what kind of pictorial can you measure a true angle on the front?

Oblique

What kind of pictorial has parallel lines converge to a vanishing point?

Perspective

Rapid prototyping

Solid physical model is made directly from 3D CAD model data without any special tooling

What does controlling design intent look like with using geometric relations?

Tangent, horizontal, concentric Ex: if you want holes to remain equal you can set up that relation

What does controlling design intent look like by placing certain dimensions?

The choice depends on how you want the part to update after changes. For example, you could place a hole position with respect to an edge or respect to a different hole

What does controlling design intent look like from a modeling approach?

What your base feature is What features you add If you take away or add material Ex: how to place holes, individually or a pattern Ex: which edges to fillet first

Can hidden lines be shown in a pictorial?

Yes

What does controlling design intent look like by using equations?

You can set a length equal to a fraction of a different length

where is the viewer in perspective projection?

a finite distance

what is characteristic of an oblique pictorial?

a parallel front face (90 degree angles)

2 kinds of CAD that evolved

additive manufacturing and numerical control machining

what kinds of drawings should always have centerlines?

all 2D drawings

pre-defined features

already defined features such as fillets or chamfers

what is the scale going back in general oblique projections?

anywhere between 1/2 and 1

why do we have fillets/chamfers?

appearance protection safety easier to coat harder to break

where is the viewer with oblique projections?

at infinity

what are the two kinds of orthographic projection?

axonometric and multi views

what are the three kinds of oblique projections?

cabinet, general and cavalier

what is the best way to figure out if views are in first or third angle?

choose one, then prove or disprove it

what do title blocks need?

company name drawing title scale drawing number

CAD

creating, changing, optimizing a design through using computerized tools

milter lines are a graphical way of keeping the _______ the same

depth

working drawings

describe shape, size and more specifications to construct an object

What kind of modeling software would you use to make late stage design changes?

direct

What kind of modeling software would you use when working with legacy data?

direct

What kind of modeling software would you use with ideation?

direct

direct modeling

direct manipulation of geometry by pushing, pulling and twisting

solid modeling

easy to visualize and manipulate lots of information can analyze and optimize can put into CAM, add. manufacturing and # control machining

detailed assembly drawings

enough info to manufacture and assemble the part

True or false: proportion controls the size of the drawing

false

true or false: construction lines are thick, light lines

false

true or false: lines that are parallel on an object are not always parallel on an axonometric view

false

true or false: selecting a surface before entering the Hole Wizard command allows you to create holes on multiple faces

false

true or false: when creating a diameter dimension for a revolve sketch, you want to select the end point of the centerline

false

True or false: proportion is stipulated y the ratio of the drawing size to the actual object size

false, that is scale

what are the two kinds of multi-views?

first angle and third angle

how do oblique planes look in all three views?

foreshortened but seen in all three principal views

how do inclined planes look in all three views?

foreshortened in two views and shown as an inclined line in the third

How can you tell a pictorial is an oblique?

front face is dead on right angles on front face are 90 degrees circles on front face are totally circular and not ellipse-like

what is the scale going back in cavalier oblique projections?

full scale

2 types of parameters

geometric constraints and dimensions

what four things affect design intent?

geometric relations dimensions (which and placement) equations method of modeling (extrude vs rotate)

surface modeling

good for rendering like putting a sheet over the wireframe

parametric modeling is good for ______ and bad because _________

good: multiple configurations and design intent bad: show performance and large file size

direct modeling is good for ___________ and bad because ________

good: speed and objects with a short life cycle bad: it is less design controlled

detail drawings

have enough detail to manufacture the part has title block

to draw non-isometric lines, you must...

have two corners to draw a line in between

multi-views must have...

hidden lines and center lines

design intent

how we want a model to behave

what is a good way to tell between an isometric and a trimetric?

if circles are foreshortened differently or "different squishyness"

what is the difference between isometric views and trimetric views?

in isometric, all angles are equal, but in trimetric, no angles are equal

in axonometric projection, the viewer is at...

infinity

in multi-views, the viewer is at...

infinity

In what kind of pictorial is the angle of the receding axis set by definition?

isometric

What's larger, isometric projections to isometric drawings?

isometric drawings

What is the difference between an isometric drawing and an isometric projection?

isometric projections are projected on a plane (scaled about 80%). Drawings use full measurements

what are the three kinds of axonometric projection?

isometric, dimetric and trimetric

what is the difference between a multi-view and an isometric pictorial?

isometrics are tilted and rotated to see all 3 dimensions instead of just 2

what is the first thing to look for when deciding what kind of pictorial an object is?

look for parallel lines, if they converge then it's a perspective drawing

wireframe modeling

makes 2D objects 3D using wires good for animation and rendering can be ambiguous no surface/volume information

2D modeling

more exact than drawing freehand less expensive if you don't need a 3D model hard to visualize, analyze and optimize ex: detail drawing, floor plan

Are dimensions along width, depth and height true length in a cavalier oblique drawing?

no

Is a multiview a pictorial sketch?

no

Should you re-use dimensions when modeling?

no

can two adjacent areas in a multi-view lie in the same plane?

no

do assembly drawings have dimensions or hidden lines?

no

In what kind of pictorial are distances foreshortened along two of the three principal axes?

none

What kinds of objects have detailed assembly drawings?

objects that will probably never be pulled apart

if front face angles are 90 degrees, what kind of pictorial is it?

oblique

if front face circles are circular, what kind of pictorial is it?

oblique

what are the two kinds of parallel projection?

oblique projection and orthographic projection

what are the three main types of pictorials

oblique, perspective and axonometric

how would you describe oblique projection?

one face parallel to the projection plane, then a receding axis going back

isometric lines are...

parallel to on axis and change in one direction

What kind of modeling software would you use for multiple configurations?

parametric

What kind of modeling software would you use to preserve design intent?

parametric

Solidworks is a...

parametric, feature-based model

in axonometric projection, the projectors are _______ to the projection plane

perpendicular

in multi-view projections, projectors are _______ to the plane of projection

perpendicular

What is the most realistic type of drawing?

perspective

what kind of projection is closest to what humans see?

perspective

what are the two types of projection?

perspective and parallel

rendering

photo realism

working drawings can be...

pictorials or multi-views *usually bad to use pictures as technical drawings because they are unclear*

assembly drawings

show how parts fit together has "exploded" views has parts list and notes for manufacturing (like cleaning and assembly)

how do normal planes look in all three views?

shown as true size in one view and shown as edges in the other two

numerical control machining/conventional manufacturing

subtractive process in which the CAD model is made into a code that drives machine tools

parametric modeling

system that models using parameters

what is the front view of a multi-view called?

the "common" or "central view"

features are...

the building blocks and are subject to parent/child dependancies (history-based) can be user-defined or predefined

how should you decide which face should be the front of an oblique projection? why?

the face with the most detail or curve (or longest dimension) features so they aren't foreshortened

if we don't know the operating position of an object, what should we go by?

the most stable position

what is the relationship between the object, viewer, and plane in first angle projection?

the object is between the viewer and the plane

what is the relationship between the object, viewer, and plane in third angle projections?

the plane is between the object and the viewer

what happens to the projectors in perspective projection?

they converge

what do converging projectors do?

they make things farther away look smaller

True or false: a child can be suppressed without suppressing its parent

true

True or false: it is possible to change the order in which a feature was created

true

True or false: oblique and axonometric projections use parallel projection

true

True or false: proportion is considered key to freehand sketching

true

True or false: proportion is helpful when creating sketches in SolidWorks

true

True or false: proportion maintains the size of one part of the sketch relative to the entire sketch

true

true or false: a center line may sometimes be short unbroken lines

true

true or false: a tangent line touches an arc/circle at one point

true

true or false: fillets and chamfers will affect the model differently depending on whether they are added before or after a shell

true

true or false: hidden lines show areas not visible in the current view

true

true or false: only two principal views are necessary to show the length, width and height of an object

true

true or false: the receding axes on an isometric sketch are drawn at an angle of 30 degrees to the horizontal

true

when do we show lines at tangent points?

when when the tangent surfaces are perpendicular

Can a plane still be oblique or incline if it is hidden from a view?

yes

what is bi-directional associativity?

you can go between any files associated with a part, when you update one file the others will update as well

what do you do to an object in axonometric projection? why?

you tilt and rotate the object so that you can see all three dimensions


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