2.1: Module 7- Visualizing Multiview Drawings

Module 7: Visualizing Multiview Drawings

Learning Outcomes

When you have completed this module, you will be able to:

1. Draw isometric drawings on an isometric grid using multiview drawings as a reference.
2. Construct 3D models in AutoCAD using multiview drawings.

Visualizing 3D Models

In the first six modules, all of the wireframe models that you constructed were referenced to a given 3D view of the model. Since most technical drawings used in the drafting and design world are 2D multiview drawings, 3D models must be able to be drawn using a multiview drawing as a reference to find the model’s shape and dimensions. To construct a 3D model, you must be able to mentally visualize the 3D model using a multiview drawing as a reference.

A good way for you to learn to visualize a 3D model from a 2D multiview drawing is to first draw the model as an isometric drawing. By doing this, it is easier to form a mental image from the multiview drawing. After practicing this for while, you will be able to visualize and construct 3D models without drawing the isometric first.

Figure 7-1
An Isometric Drawing

An isometric drawing is a 2-dimensional drawing that has the XYZ axis drawn at 120 degrees apart as shown in Figure 7-1. In this module, drawing the isometric on an isometric grid will be taught. An isometric grid has the grid lines drawn at 120 degrees as shown in Figure 7-2. Figure 7-3 shows a rectangular box drawn on the isometric grid.

Figure 7-2 An Isometric Grid

Figure 7-3
A Rectangular Box Drawn on an Isometric Grid

WORK ALONG: Visualizing 3D Models

Step 1

Using the NEW command, start a new drawing using the template: 3D Layout English.

Step 2

Save and name the drawing: AutoCAD 3D Workalong 07-1.

Step 3

Set the UCS to World and the view to Top. Enter the UNITS command. In the Units dialogue box, set the Insertion Units to Inches. Using the INSERT command, insert the block: AutoCAD 3D Workalong 07-1 at the coordinates 0,0,0. Explode the block. The drawing should appear as shown in the figure. (Figure Step 3)

Figure Step 3

AUTHOR’S COMMENTS: In this workalong, you will be using AutoCAD to draw isometric drawings of objects on atwo-dimensional isometric grid. This is only a teaching tool to help you visualize 3D models using the multiview drawing of the object. Isometric drawings were used extensively in the drafting field before CAD was used.

With AutoCAD, you can draw in true 3D and isometric drawing are not really required. They are, however, a good teaching tool for this module.

Step 4

Change the layer of the isometric grid from layer: 0 to layer: Grid.

Step 5

Lock layer: Grid and set the lineweight of layer: Object to 0.35 mm. (Figure Step 5)

Figure Step 5

Step 6

Enable OSNAP and LWT. (Figure Step 6)

Figure Step 6

Step 7

Figure Step 7A shows the multiview drawing of Object 7-1. Set layer: Object as the current layer and draw a box 6 grids long, 5 grids wide and 4 grids high. Where it is drawn is not that important but it should be located somewhere in the top left corner. Ensure that all lines are snapped to the grid intersections. Since layer: Grid is locked, the lines can be freely moved on layer: Object, as required. (Figure Step 7A, 7B, and 7C)

AUTHOR’S COMMENTS: One grid on the multiview drawing equals one grid on the isometric.

Figure Step 7A
Multiview Drawing – Object 7-1

Figure Step 7B

Figure Step 7C

AUTHOR’S COMMENTS: Solve one view at a time. Pick the view with the hardest contour to start with. In this case, start with the Front view.

Step 8

To draw the contour of the Front view, count the number of grids for the diagonal cut off. It is 3 grids on the X axis and 2 grids on the Z axis. Using those dimensions, draw the inclined lines on the front and rear view and add the lines to connect them. (Figure Step 8)

Figure Step 8

Step 9

Trim and delete the lines to complete the contour of the front view. (Figure Step 9)

Figure Step 9

Step 10

Add the lines to cut out the contour of the Right Side view. (Figure Step 10)

Figure Step 10

Step 11

Trim and delete the necessary lines to complete the Right Side view contour and then add the lines to form the Top view contour. (Figure Step 11)

Figure Step 11

Step 12

Trim and delete any unwanted lines to complete the isometric object: Object 7-1. The drawing should appear similar to figure. (Figure Step 12A and 12B)

Figure Step 12A

Figure Step 12B

Step 13

Using what was just taught, draw the isometric drawing of: Object 7-2. Draw it in the top right corner of the grid. (Figure Step 13)

Figure Step 13

AUTHOR’S COMMENTS: Solve one view at time. Pick the view with the hardest contour to start with. In this case, start with the Front view.

Step 14

The figures show the necessary steps. Try to complete the isometric without looking at the figure. (Figure Step 14A, 14B, 14C, and 14D)

Figure Step 14A

Figure Step 14B

Figure Step 14C

Figure Step 14D

Step 15

Your drawing should now appear similar to the figure. (Figure Step 15)

Figure Step 15

Step 16

Using what was just taught, draw isometric drawings of the four objects: Object 7-3 to Object 7-6. For the answers, see Figure “Isometric drawing of Object 7-1 to Object 7-6” at the end of this chapter. Try to visualize the 3D model by looking at the multiview drawing and then draw the isometric. Do not look at the answers until you have done your best to complete the isometric drawing of each object. (Figure Step 16)

Figure Step 16

Step 17

Save and close the drawing.

Key Principles

Key Principles in Module 7

1. An isometric drawing is a 2-dimensional drawing that has the XYZ axis drawn 120 degrees
2. An isometric drawing is only used in the AutoCAD 3D book as a teaching They are mostly obsolete in the CAD design and drafting world.

Lab Exercise 7-1

Time allowed: 40 minutes.

Drawing Name	Template	Units
AutoCAD 3D Lab 07-1	3D Layout English	Inches

Step 1

Draw all construction objects on layer: Construction and all model objects on layer Model. When complete, freeze layer: Construction.

Step 2

Draw a wireframe model of the object. (Figure Step 2A, 2B, and 2C)

AUTHOR’S COMMENTS: Draw the Front view first.

Figure Step 2A
Dimensioned Multiview Drawing

Step 3

Start with the current view SE Isometric. If required, orbit it slightly with 3DFORBIT to help your line of sight.

Step 4

Enter the UNITS command. In the Units dialogue box, set the Insertion Units to Inches. Change the current UCS to World and check the model with the key.

Figure Step 2B
Complete Wireframe Model

Figure Step 2C
Solid Model – SE Isometric View

Isometric drawing of Object 7-1 to Object 7-6