Lesson Plan Industry Sector
Engineering & Design

## Step-V Pulley Half Section, Isometric

### Lesson Plan Overview / Details

In this lesson students will create an isometric pictorial view of the Step-V Pulley with one quarter section removed. This is the corresponding pictorial to the previously created half section view.

### Lesson Time

Two class periods
140 Minutes

### Objectives and Goals

• Students will work with ACAD isometric drawing techniques
• Students will gain a better understanding of what the half section view represents

### Activities in this Lesson

• Show students the motorcycle motor and then show the cutaway drawing of it. Hopefully they appreciate just how informative a cutaway pictorial can be.  Then show them the two car cutaways- WOW! The Isometric Half Section is probably the most common type of cutaway drawing. Lets begin...

• In order to create an isometric drawing in ACAD, the student will have to change a Snap setting. This is done by right clicking on the SNAP button at the bottom of the screen. A Drafting Settings window should then appear. To change from the standard rectangular drawing style to isometric, simply click Isometric Snap as shown in this screen shot.

• Getting Started - Demo / Modeling

Drawing lines in the isometric setting is somewhat different from the standard rectangular drawing style. The main difference is that the popular OFFSET drawing technique cannot be used because the OFFSET command will not conform to the Isometric Snap. To get started, the student needs to make sure he is in the correct isometric plane. The student can toggle between the three planes using the F5 key. This lesson starts in the "left" isometric plane. Next, with ORTHO mode on, go into the LINE command, click on the starting point of the line, drag the cursor along the appropriate axis, and enter the correct magnitude. To create object lines that do not follow the major axis (for example: the angled walls of the groove), the student will first need to create intersecting construction lines at what will be the end points of the angled object line. Having done this, the angled object line will be easy to create, just click on the intersections for the start and end points of the object line.

• In order to finish the upper section outline the student should create the remaining two V- Grooves by copying the first V-Groove he created. Be sure he utilizes the appropriate construction line intersections as base points.  Once the grooves have been created the student can complete the remaining outline. The lower section outline is then created in the same manner as the upper with one exception: it is created in the "top" isometric plane. Simply toggle between planes with the F5 key to get into the correct plane.

• With the completion of the upper and lower section outline, all straight line work is finished. What remains are the arcs joining the two outlines. These arcs are created from isometric circles that are then trimmed to the edges of the outlines.  To get started the student needs to get into the "right" isometric plane. The isometric circle is actually created by selecting the ELIPSE command and then typing “I” for ISOCIRCLE. The student is prompted to enter the circle’s center. This point can be found by extending a construction line from the appropriate point on the V-Groove outline to the axis of the pulley. The student is then prompted to complete the circle by selecting the endpoint of its radius. This should be the before mentioned appropriate point on the V-Groove outline.

• In order to complete the view, all of the isometric circles must be trimmed to the upper and lower section outlines using the TRIM command. Finally section lines are added using the HATCH command. The default values should be adequate requiring the student to simply select the interior regions of the upper and lower section outlines to complete the operation. The final step is to add the complete Half Section Isometric View to the original dimensioned view created in the previous lessons. This is simple enough to do using either the MOVE command or the COPY command, but there is one obstacle: the view is too big. This problem is quickly alleviated by using the SCALE command to shrink the isometric view. Simply enter the SCALE command, select the view, and enter “.5” as the scaling factor. Now the view should easily fit in the upper right hand corner of the now finished drawing.

### 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