Engineering Drafting is explored by the use of ACAD 2002. Lesson 5 we were introduced to the function of cams and how diverse there use is in our world of machines and machine parts. There are precise techniques used in Engineering Cams. Four kinds of motion are involved with cam design and these are straight line, harmonic, dwell and parabolic. Each of these type of motion are involved in the rise and fall of a follower that is attached or rests on the surface of a cam. The above student illustrations are visual examples of camshaft function. In this lesson you will be creating the Displacement Diagram and Profile of the above animated Cam.

Cams are everywhere and serve to transfer rotary motion into some form of lateral or reciprocating motion. One can find cams in an automobile, in a door lock, in airplane landing gear and within an internal combustion 4 stroke engine. These are but a few examples or cams in our everyday world.

Connecting Your Learning

As you work your way through this lesson, you should reflect on the following questions:

What is the function of a Cam?
What are the 4 types of Cam Motion?
What is the difference between rotary and lateral motion?
What does a cam serve in an automobile engine?
What does a cam serve in a door lock?

The State of Arizona has assembled Drafting standards to make sure that Instruction is thorough and well thought out by the instructor. By clicking on the hyperlink below will upload to your browser window the entirety of these standards. The standards that are addressed in this lesson are below the hyperlink.

1.0 USE BOARD DRAFTING EQUIPMENT, INSTRUMENTS AND MEDIA.

• 1.1 Analyze Drawing surfaces for Drafting
• 1.6 Demonstrate Sheet Setup skills

2.0 DEMONSTRATE SKETCHING, LETTERING, AND LINE SKILLS.

• 2.1 Demonstrate freehand sketching skills for drafting applications.
• 2.2 Demonstrate lettering skills.
• 2.3 Demonstrate line work.

6.0 DEMONSTRATE GEOMETRIC CONSTRUCTIONS

• 6.1 Measure Geometric Constructions.
• 6.2 Develop Geometric Constructions.

8.0 APPLY BOARD DRAFTING SKILLS TO COMPUTER-AIDED DESIGN/DRAFTING (CADD)

• 8.1 Demonstrate computer skills for a CADD system.
• 8.2 Create dimensional CADD entities.
• 8.3 Create 3 dimensional CADD drawings.

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The State of Arizona has also assembled Math standards and many of these apply directly to the vocational subject area of Drafting. Drafting is a very precise discipline and the use of mathematics is integral to design and manufacturing. Below are the math standards that are involved in this lesson

1M-P1. Compare and contrast the real number system and its various subsystems with
regard to their structural characteristics

• PO 2. Compare subsets of the real number system with regard to their properties
  (commutative, associative, distributive, identity, inverse and closure properties)

1M-P2. Construct, interpret and demonstrate meaning for real numbers and absolute

• PO 3. Solve real-world distance problems using absolute value
• PO 4. Determine, among the solutions to a real-world problem, which, if any, is reasonable
• PO 2. Define absolute value as the distance from the origin

4M-P1. Interpret and draw three-dimensional objects

• PO 1. Sketch prisms, pyramids, cones, cylinders and spheres
• PO 2. Classify prisms, pyramids, cones, cylinders and spheres by base shape and lateral surface shape.
• PO 3. Recognize the three-dimensional figure represented by a two-dimensional drawing.
• PO 5. Make a model of a three-dimensional figure from a two-dimensional drawing and make a two-dimensional representation of a three-dimensional object (models and representations include scale drawings, perspective drawings, blueprints or computer simulations)

4M-P4. Deduce properties of, and relationships between, figures from given
assumptions

• PO 1. Find similarities and differences among geometric shapes and designs using a given attribute (e.g., height, area, perimeter, diagonals and angle measurements)
• PO 2. Identify arcs, chords, tangents and secants of a circle
• PO 3. State valid conclusions using given geometric definitions, postulates and theorems
• PO 4. Represent pi as the ratio of circumference to diameter
  

Lesson Objectives

1. Draw using ACAD 2002 the Displacement Diagram and Profile of Cam # 3.
2. Use the Array command to arrange lines that will represent on the Cam Profile the various kinds of motion described in its Displacement Diagram.
3. Understand how to use the commands of : line, copy, move, the @ command and vectoring,
4. Create a region from the Cam Profile and create a 3d model by extruding this region.
5. Use the Rotate3d command and orient the extruded model in Plan View and scale to 1/2.

Key Terms

"click on the key on any of these terms and it will hyperlink to the course glossary"

isometric	Harmonic Motion	Parabolic Motion	Linear Motion
Dwell	grid	unidirectional	aligned
font	line weight	scale	dimension
layers	extension lines	Displacement Diagram	Cam Profile

 

Instruction

Your Text Book and Reading Assignments

Summary and Assessment