Lesson Plan Industry Sector
Engineering & Architecture

## Step-V Pulley Half Section, Orthographic

### Lesson Plan Overview / Details

This lesson teaches the student how to create a half section view. The object being drawn is a typical step-v pulley, the kind used to power the various engine belts found on a car. The three following lessons will teach students how to dimension their drawing, create an isometric pictorial, and a solid model.

### Lesson Time

Two class periods
140 Minutes

### Objectives and Goals

• Students will understand the advantages of the half section view
• Students will work with ACAD "layers"
• Students will work with ACAD commands such as "copy, mirror, and hatch"

### Activities in this Lesson

• Show students the fan belt video clip. Next show students pictures of step-v pulley. Explain how the pulley drives the belts and why you would not want to do what is shown in the video-FINGERS! Hopefully they will now have an understanding of what a step-v pulley is.

Ask them if they feel they could draw up the plans for the object. They may feel the drawing would be simple, but what about the inside of the pulley? Unlike the previous solid objects they have drawn, this object is hollow with several internal features. In order to see these internal features in real life, we would need to cut a chunk out of the pulley. That is exactly what we will do with the drawing. We will draw the object as it would appear if one quarter of it had been cut out and removed.

#### Resources and Materials

• Show students Fig. 5-7. Explain how the half section is created from two cutting planes at right angles to each other along the centerline. The half section is only useful on symmetrical objects because it is assumed that the exposed internal features are the same on both sides. Besides revealing the interior features, the main advantage to the half section is that it also shows the exterior features. That is; one drawing view is able to show both exterior and internal features. If the object is both symmetrical and cylindrical, the half section view is the only view necessary to completely describe the object, as is the case for the step-v pulley. The complete drawing should now be shown to the students. Also show them the solid model to help clarify their understanding of the object’s geometry. They will be creating the solid model last.

#### Resources and Materials

• Setting up the Layers Demo / Modeling

The first thing students will need to do is set up their layers as shown in this snapshot. If nothing else students need to be shown how to create and take advantage of the construction line layer. They must be required to first draw the object in construction lines (XLINE) on the construction layer without trimming. Then they need to trace over the construction lines in the object layer using a heavier line weight.

#### Resources and Materials

• When students are ready to begin creating lines they should start with the smallest diameter V groove. Once completed, they can use the COPY command to create the other two V grooves. This should complete the outer contour of the “section” half of the view. Next students should complete the interior geometry. Once all the geometry in the “section” half of the view is finished, this geometry should be reflected about the object’s center line using the MIRROR command. This newly mirrored geometry should be converted into a standard orthographic drawing which includes hidden lines. It is easy to convert the internal object lines to hidden lines by simply selecting them and then clicking on the Hidden Line layer in the Layers toolbar.

The Half Section view is now complete and students should move on to dimensioning. Please see the next lesson.

### Assessment

Assessment Types:
Projects, Observations,

Informal assessment is conducted through casual observation during student work sessions. The Formal assessment is made when the student turns in his completed drawing.