ENG 004 Final

Visual Thinking

A phenomenon of thinking through visual process

Visualization Methods

Sketching and CAD

3 roles of graphics in design

Visualization, Communication, Documentation

Visualization

- Ability to see object in your mind
- Sketches are the first physical capture of your mental image

Communication

- Refine drawings and models• To improve the clarity of graphics
- Communication of idea with others

Documentation

- Detailed 3D and 2D drawings
- Contains all information needed to create/manufacture/use object(s)

Ideation

the formation of ideas or concepts

Linear Engineering Design

Traditional Engineering Design

Model-centered engineering design

3 major activities: Ideation, refinement, implementation

Sketching vs. Drawing

-Sketching: Transferring of ideas or concepts onto paper or into a computer to quickly capture them graphically.
-Drawing: Transferring of an object's size, shape, proportion and/or main features onto paper or into a computer.

Design Sketch

Rough sketches that are used to quickly capture an idea. They tend to have less detail, structure and restrictions than freehand or technical illustrations.

Technical Illustration

Detailed drawing with restrictions, dimensions, and structures.

Contour Sketching

sketching the outline of an object

ANSI (American National Standards Institute)

The national standards institute of the
United States, which facilitates the
formation of a variety of national standards for STEM

ISO (International Standards Organization)

The organization which sets the international standard for manufacturing.

ASME (American Society of Mechanical Engineers)

A professional engineering organization that is known for setting codes and standards for mechanical devices in the United States.

Visible Lines

used to represent features that can be seen in the current view

Dimension and Extension Lines

used to indicate the sizes of features on a drawing

Hidden Lines

used to represent features that cannot be seen in the current view

Center Lines

lines that define the center of an arc,circle, or symmetrical parts.

Cutting Plane Lines

used in section drawings to show the locations of cutting planes

Section Lines

Thin lines used in a section view to indicate where the cutting plane line has cut through material.

Break Lines

Lines used to terminate features on a drawing when the extent of the feature has been clearly defined and no additional detail is needed.

Isometric Sketch

A form of pictorial sketch in which all three drawing axes form equal angles of 120 degrees with the plane of projection.
-Orthographic Projection

Oblique Sketch

The object face that is placed parallel to the frontal plane will be drawn true size and shape
-Non-orthographic projection

single point perspective

A technique for achieving a sense of depth by establishing a single vanishing point and painting or building all objects to diminish to it.
-Non-Orthographic

Vanishing Point

A point in space, usually located on the horizon, where parallel edges of an object appear to converge.

Ground Line

a base line upon which figures stand

two point perspective

two vanishing points
-Non-Orthographic

Multi-View Drawing

A drawing which contains views of an object projected onto two or more orthographic planes.
-Orthographic

Cartesian Coordinate System

A rectangular coordinate system created by three mutually perpendicular coordinate axes, commonly labeled X, Y, and Z. Can be 2D with just XY plane

polar coordinate system

A two-dimensional coordinate system in which each point on a plane is determined by a distance from a reference point and an angle from a reference direction.

Spherical Coordinate System

Uses angular measurements on a sphere to specify locations (r, φ, θ)
x = r cosφ cosθ
y = r sinφ
z = r cosφ sinθ

cylindrical coordinate system

(r, θ, z)
- x = r cosθ
- y = r sinθ

Absolute Coordinates

The exact location of a specific point in terms of X, Y, and Z from the fixed point of origin

Relative Coordinates

The location of a point as given by the distance from the last point specified.

World Coordinates

- "Stationary" or "Fixed"
- Never changes position or orientation relative to the model

Local Coordinates

- Coordinate system defined by the designer or CAD system.
- May located and oriented anywhere in any direction within the world coordinate systems.

Primitives

the building blocks/elements used to create CAD models

Node

Most basic primitive. A single point.

Spline Curve

A spline curve is a smooth, freeform curve that connects a series of control points.

Interpolated curve

Every point is on the spline curve

Bezier Curve

Spline with two endpoints and control points to specify curve direction.

B-Spline

Higher level of complexity of Bezier. degree of curve can be changed without changing # of points. several curves joined at knots

Geometric Constraint

Constant, non-numerical relationships between the parts of a geometric figure. Examples include parallelism, perpendicularity, and concentricity.

Conditions vs. Constraints

• Conditions are like constraints, but they are not enforced.
• Conditions are simply the geometric state of the feature.
• Conditions are simply the state of the feature at a given moment or location.
• Constraints remain enforced until the designer releases them.

Generatrix

a point, line, or surface whose motion generates a line, surface, or solid

Directrix

fixed line

Steps to create a solid model

1. Define workplane
2. Define profile (Sketch)
3. Solid Geometric Modeling

Perpective Projection

- Line of sight radiates from the observer
- The most realistic natural view

Parallel Projection

Line of sight is parallel to the observer

Orthographic Projection

Line of sight is perpendicular to the projection plane

Oblique Projection

Line of sight is not perpendicular to the projection plane

Axonometric Projection

- Line of sight perpendicular to projection plane
- A type of orthographic projection
- Parallel projection technique

Isometric

- Type of Axonometric Projection
- Angles A, B, and C are equal
- Corners MZ, MX, and MY are equal in length

Dimetric

- Type of Axonometric Projection
- Angles A and C are equal
- Corners MX and MY are equal in length

Trimetric

- Type of Axonometric Projection
- No equal angles or corners

Third Angle Projection

Used by ANSI and JIS

First angle projection

Used by ISO and DIN

Principles of Orthographic Projection

- Alignment of feature
- Distances of related views must be equal

True Size (TS)

LOS are perpendicular to the feature

Edge View/Point View (EV or PV)

LOS are parallel to feature

Oblique View (OV)

LOS are neither parallel nor perpendicular to feature

Default Tolerance

Tolerance used when it is not otherwise specified

Reference Symbol

( )

Places/Times Symbol

X

Counterbore

Countersink

Depth

Dimensional Tolerence

Tolerance of size and location

Geometric Tolerence

Tolerance of form (Perpendicularity, flatness, etc)

Inch Dimensions

- # of decimals equal (ex: 8.900 and 4.896)
- No 0 before decimals under 1 (ex: .98)

Metric Dimensions

- # of decimals not equal (ex: 8.9 and 4.896)
- Include 0 before decimals under 1 (ex: 0.98)

Maximum Material Condition (MMC)

Size of a feature at one end of its tolerance zone where
there is the most amount of material.

Least Material Condition (LMC)

Size of a feature at one end of its tolerance zone where
there is the least amount of material.

Class of Fit

An assembly of two parts creates a “fit” whose
functional characteristics is determined by the
difference in the parts’ associated sizes.

Clearance Fit

MMCH > MMCS
- Always leaves space when assembled

Interference Fit

LMCH < LMCS
- Parts always intersect when assembled

Allowance

Smallest hole - largest fit =

Transition Fit

Two toleranced mating parts are sometimes an interference fit and. sometimes a clearance fit when assembled.
- MMCH > LMCS
- LMCH < MMCS

ISO fit recommendations

■ Capital letters refer to the hole
■ Lowercase letters refer to the shaft
■ Basic size is the nominal size of both members

Hole Symbol

Capitol letter

Shaft Symbol

Lowercase letter

Fit Symbol

Hole tolerance/shaft tolerence
ex. H8/f7

Feature control frame

Used to specify the geometric tolerance. It is divided into two or more zones.

Datum

Reference point or surface

Straightness (FORM)

compares a line on a part to a perfectly straight line.

Circularity (FORM)

evaluates a circle to a perfect circle.

Flatness (FORM)

evaluates the largest vertical distance
between the highest and lowest points on a surface (plane).

Cylindricity (FORM)

compares a cylinder to a perfect cylinder.

Parallelism (ORIENTATION)

Specifies the degree to which a feature's orientation may vary with respect to its referenced datum by creating a tolerance zone parallel to that datum.

Perpendicularity (ORIENTATION)

Specifies the degree to which the orientation of a right-angled part feature may vary.

Concentricity (LOCATION)

he condition in which the axes of
all cross-sectional elements of a cylinder (cone or sphere)
are common to a datum axis.

Circular runout (RUNOUT)

Used to control the location of a circular part feature relative to an axis.

Section views

Clarify the interior geometry by removing a portion of a part in a sketch

Cast Iron

Material used for the general section lines

Full Sections

Made by passing the imaginary cutting plane completely through the object.

Half Sections

Show features of up to ½ of the part (Usually these parts have circular symmetry.)

Offset sections

Used to include features not found
on a single plane but on parallel planes.

Aligned Sections

Used to show features not on a single cutting plane, nor parallel cutting planes, but on cutting planes that intersect through a single axis.