Technical Illustration essentially is an art and a science of taking orthographic views and creating a three dimensional image.

There are three standard isometric views and you will be exploring these views in this lesson. With some illustrations and depending upon certain characteristics of a model one view might be used better than another.

Along with our Standard views come the angle of a part of the model which is not isometric. By using an ellipse and the technique of circle projection these angles can be projected onto a model that is drawn in isometric perspective. A draftsman can also create a 3d image of the same model and orient this image in isometric view. The Illustrator can then compare the accuracy of both drawings.

A Draftsman not only makes the blueprint but their responsibilities also lie in being able to present the print so others can visualize what the model looks like. In this lesson the Draftsman has to make the choice as to what Isometric view or 3d image would best be suited to illustrate the model in question. Are they both as accurate? We will explore in this lesson drawing and comparing the Isometric with the 3d.

Connecting Your Learning

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

What is the function is of the iso ellipse command and the ellipse command in determining the major and minor axis of an ellipse?
What is an Isometric drawing?
What type of Isometric view is used to show the bottom of an object?
What are Projection lines?

 

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
  

Instruction

The following are the models that will be used for Lesson 7:

• Lesson 7a: [drawing Problem 5.5 on page 119 of the Thomas Text in Isometric perspective]
• Lesson 7b: [drawing Problem 5.5 on page 119 of the Thomas Text as a 3d image]
• Lesson 7c: [drawing Problem 5.11 on page 120 of the Thomas Text as a 3d image]

For this model you will be drawing the isometric view of the above model and using the technique called 'Circle Projection" to determine the angle of the slanted surface of the "base angle bracket". You will be creating the 3d image of the above model and compare the 2 types of drawings.

I will explain this further in the lesson 7 media disc. Please insert the media disk and listen to lesson 7.

*Note: The Lessons are best viewed with real player and you can download the latest version by clicking on the words real player.

Your Text Book and Reading Assignments

Summary and Assessment