UNIT 5 OVERVIEW
Geometric Relationships
Preface
The process of design is inherently graphical. As ideas are developed they are often
jotted down on paper for later recollection and/or further development. As a designer
progresses through the design process and ideas are formalized, greater accuracy is
required. At this point, sketches are converted to more formal drawings, which include
annotations describing the size and characteristics of the design features. Engineers and
draftspeople who have a strong understanding of shapes and other geometric
relationships develop these formal drawings. Whether the drawings are created on a
computer or by manual drafting techniques, an understanding of geometric relationships
is very important.
Today’s software that employs parametric design functionality requires an understandingof geometric relationships, such as perpendicular, parallel, and tangent. These concepts,however, can be difficult for students to understand. Physically constructing these
relationships, using a compass and straight edge, can help students grasp the concepts and
retain them for later use. Following an activity on geometric construction, students can
transfer the knowledge of geometric relationships to parametric design software.
Parametric design modeling software also implies an understanding of coordinate
systems. Students must have a thorough understanding of the Cartesian Coordinate
System and how points are plotted in space. Furthermore, students need to know how to
plot points using absolute, relative, and polar coordinates. These skills will become even
more important as students progress from design to the prototyping process. For
example, prototyping tools, such as computer numeric controlled machines and rapid
prototyping tools, require this knowledge in order to program them.
Assessment (pg.131) Section 6.5 Computer Modeling Sketching
Name______Date______Period ______
Directions: Multiple choice and True/False. Select the most appropriate answer and
place the letter corresponding to that answer on the line provided.
1. ____ The first step in creating a model using a CAD program is to:
A. Extrude B. Profile
C. Constrain D. Sketch
2. ____When you start a new sketch, the axes represent the sketch coordinate system.
A. X and Y B. Y and Z
C. Z and X D. None of the above
3. ____Creating sketch geometry is as easy as drawing a closed shape.
Which of the following is a simple rule for successful sketching?
A. Keep the sketch simple B. Draw roughly to size and shape
C. Accept default dimension D. All of the above
4. ____ Lines, circles, arcs, and rectangles are all examples of:
A. Three-dimensional sketching tools B. Dimensioning tools
C. Inquiry D. Two-dimensional sketching tools
5. ____To place linear, angular, radius and diameter sizes, you would use:
A. Three-dimensional sketching tools B. Dimensioning tools
C. Inquiry tools D. Two-dimensional sketching tools
6. ____A two-dimensional sketch can be analyzed to determine its:
A. Linear length B. Area
C. Volume D. Both A and B
7. ____Elements of a sketch can be adjusted by:
A. Changing dimensions B. Applying constraints
C. Grip editing (selecting and dragging) D. All of the above
8. ____This feature places a pattern or lattice of dots on the sketching
surface, making it easier to locate points.
A. Snap B. Grid
C. Limits D. Ortho
9. ____All two-dimensional drawings are superimposed on an invisible
grid, or coordinate system, with a horizontal X axis and a vertical Yaxis.
A. True
B. False
10. ____The process of using lines, circles, arcs, and rectangles to createthe basic design element that defines the approximate size and shapeof features in a part.
A. Sketching B. Dimensioning
C. Visualization D. Modifying
Assessment (142) Section 7.1A Adding Components
Name______Date______Period ______
Directions: Multiple choice and True/False. Circle the best answer.
1. The first component placed in an assembly should be a fundamental part or subassembly,
such as a frame or base plate, on which the rest of the assembly is built.
A. Base component B. Internal component
C. External component D. Projected component
2. This function presents the content of an assembly in a hierarchy. Components are
listed in the order in which they are placed in the assembly.
A. Panel bar B. Grounded component
C. Assembly browser D. Component tool
3. This describes a circumstance in which components are listed in the order in which
they are placed in the assembly.
A. Model component B. Browser hierarchy
C. Assembly constraint D. Wireframe view
4. The panel bar contains current command icons or command names depending on how
it is configured.
A. True
B. False
5. This function allows the production of in-place parts in assembly.
A. Create component tool B. Edit component tool
C. Panel bar D. Design view toolbar
6. This function duplicates one or more components and arranges the resulting
occurrences in a circular or rectangular arrangement.
A. Collision detection B. Project geometry tool
C. Constrained drag D. Patterning components
7. This operation is done in the design process when you need to exchange one or more
components in an assembly with an improved version.
A. Replace component B. Component finder
C. External component D. Base component
8. The first component placed in an assembly, such as a frame or base plate, on which
the rest of the assembly is built. This is also a part or sub-assembly for which all six
degrees of freedom have been removed relative to the assembly origin.
A. Annotated part B. Grounded part
C. Component part D. Internal part
9. The portion of the user interface that appears under the title bar in the graphics
window. It contains icon buttons for tools that are used throughout the modelsoftware.
A. Icons B. Tools
C. Tool bar D. Component tool
10. An image of a single command function in pictorial form.
A. Icon B. Part library
C. Grid D. Function
11. A two- or three-dimensional representation of an object. This object represents awireframe, hidden edge, or shaded display.
A. Annotation B. Model
C. Patterning D. Browser
12. This is an individual part of a model.
A. Feature B. Patterns
C. Panel toolbar D. Component
13. This is a group of items in which two or more components have been constrained.
A. Assembly model B. Part model
C. Material model D. Process model
14. This object has been created as a separate part file outside of the current assemblymodel.
A. Internal component B. Internal feature
C. External feature D. External component
15. This object has been created as a separate part file inside of the current assemblymodel.
A. Internal component B. Internal feature
C. External feature D. External component
Assessment Section 7.1B Adding Components (146)
Name______Date______Period ______
Directions: Multiple choice and True/False. Circle the best answer.
1. This action button on the assembly toolbar will allow the dragging of individual
components in any linear direction in the viewing plane.
A. Copy button
B. Move button
C. Rotate button
D. Drag button
2. This action button on the assembly toolbar will revolve an individual component
about a specified point on or near the component.
A. Copy button
B. Unconstrained move button
C. Rotate button
D. Constrained move button
3. This function will duplicate a component as many times needed and in any direction
without regard to any pattern.
A. Copy button
B. Unconstrained move button
C. Rotate button
D. Constrained move button
4. This kind of move honors previously applied geometric rules. That is, the selected
components, move together in their current positions.
A. Constrained move
B. Copy
C. Unconstrained move button
D. Rotate
5. This kind of move is simply a temporary "get out of the way" move.
A. Rotate
B. Copy
C. Constrained move
D. Unconstrained move button
SECTION 7.2
Assembly Constraints (149)
Background Narrative:
In the previous section, we were introduced to the part modeling, adding components,
and part manipulation functions. We will now apply those skills along with the assembly
constraint functions to remove degrees of freedom from the components to produce an
assembly model. Constraints are the rules that determine how parts in an assembly are
placed relative to other parts in the assembly. As constraints are applied, degrees of
freedom are removed from the part, controlling its movement along a predetermined axis.
In this section, we will learn how to apply the assembly constraints of insert, tangent,
angle, mate, and flush. These constraints may be placed between faces of features, part
edges, points, inferred axes, and part work features, such as planes, axes, and points.
Vocabulary/Terms:
Performance Objectives:
1. Students will explore and demonstrate assembly modeling skills to solve a variety of
design problems.
2. Students will perform part manipulation during the creation of an assembly model.
3. Students will apply assembly constraints to successfully construct a multi-part object.
Activities:
1. Students will complete instructor-selected activities for the following assembly
constraints: insert, angle, tangent, mate, and flush.
2. The instructor should review the contents of the PLTW® Design Resource Guide
before selecting the activities.
Assessment Section 7.2 Assembly Constraints (152-153)
Name______Date______Period ______
Directions: Multiple choice and True/False. Circle the best answer.
1. These are rules that remove the degrees of freedom between two selected
components, positioning them relative to one another.
A. Assembly constraint B. Geometric constraint
C. Interference constraint D. Base constraint
2. The flush constraint aligns components adjacent to one another with faces flush.
Positions selected faces, curves, or points so that they are aligned with surface
normals pointing in the same direction.
A. True
B. False
3. The tangent constraint causes only curves to be tangent to other curves.
A. True
B. False
4. This assembly constraint positions edges or planar faces on two components at a
specified number of degrees from each other.
A. Tangent B. Flush
C. Mate D. Angle
5. This process describes the modifying of constraints in the browser.
A. Adding constraints B. Editing constraints
C. Browsing constraints D. Dispensing constraints
6. This constraint selects geometry on two components to constrain together. An
individual can specify one or more curves, planes, or points to define how pieces fittogether.
A. Flush B. Tangent
C. Insert D. Mate
7. This constraint position selects faces normal (perpendicular) to one another with faces
coincident.
A. Mate B. Tangent
C. Angle D. Insert
SECTION 7.4
Sub-Assemblies (161)
Background Narrative:
The solid modeling package has the ability to create and use sub-assemblies to efficiently
manage the construction of large assembly models. Experienced users often create their
own catalog of sub-assemblies to be used in future models. This strategy could be
applied to the train wheel linkage and pin components. When designing a sub-assembly,
any of the following may be employed: component groups that repeat in an assembly,
combinations of standard parts that are common to many assemblies, and components
that combine to perform a common function in an assembly.
Vocabulary/Terms:
- Assembly Model
- Component
- Internal Component
- Collision Detection
- External Component
- Sub-Assembly
Performance Objectives:
1. Students will employ sub-assemblies during the production of assemblies.
2. Students will explore and demonstrate assembly modeling skills to solve a variety of
design problems.
Assessment Section 7.4 Sub-Assemblies (163)
Name______Date______Period ______
Directions: Multiple choice and True/False. Circle the best answer.
1. A group of components that are constrained to act as one in a larger assembly is known as a sub-assembly.
A. True
B. False
2. When designing a sub-assembly, component groups that repeat in as assembly cannot be used to create a valid sub-assembly.
A. True
B. False
3. Combinations of standard parts that are common to many external assemblies can be used to create a valid sub-assembly.
A. True
B. False
4. Components that combine to perform a common function in as assembly may be defined as a valid sub-assembly.
A. True
B. False