There are many techniques used in technical illustration. In this lesson will be practicing the methods of drawing various shapes, and irregular shaped objects using the ellipse to make spheres, angles and hexagons.

This particular lesson will lead into other lessons using the above techniques where you will learn how to draw intersections, sections, fillets, rounds, chamfers, holes and the torus. Aircraft station points will also be drawn. All of the models will be drawn both isometrically and in 3d.

The construction and use of a sphere isometrically represents a circle in reality but the Technical Illustrator's techniques underscore that the circle being represented is actually 1-1/4 larger than the ellipse that is being drawn.

In lesson 8 we will be warming up with drawing and isometric sphere and section the sphere as well as replicating the same sectioning technique in 3d.

Connecting Your Learning

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

Is an ellipse a Circle?
How is a circle/ellipse sectioned in a drawing?
How are flat surfaces projected on a sphere?
How am I going to orient objects in paper space?
How is only part of a sphere represented in Technical Illustration?

 

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 a sphere isometrically and in 3d..
2. Rotate an ellipse to create a sphere.
3. Section a sphere.
4. Draw a flat surface on a sphere.
5. Orient a 3d image to an isometric perspective.
6. Convert meters to inches from information about oxygen and hydrogen from the periodic table.
7. Create a scale for the drawing of water molecule with oxygen and hydrogen radii.
8. Draw a water molecule isometrically and in 3d.

Key Terms

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

isometric	long axis	ellipse	orthographic
projection lines	sphere	reverse axis	ellipse
intersections	sections	glass box
Iso Ellipse	proportion	ellipse	Angstrom

 

Instruction

The following are the models that will be used for Lesson 8:

• Lesson 8a: [An Isometric replication of lesson 8a as seen below].
• Lesson 8b: [A 3d Replication of lesson 8b as seen below].
• Lesson 8c: [a 3d drawing of a water molecule (refer to the hyperlink above]
• Lesson 8d: [An Isometric drawing of a water molecule]

I will explain this further in the lesson 8 media disc. Please insert the media disk and listen to lesson 8.

*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