Module Four: Multiview Drawings


Objectives

Introduction

Projecting Views

Hidden Surfaces & Edges

How Many Views?

View Spacing & Alignment

Sample Projections

Activities


Unit Objectives

Multiview Drawings


Foundational Objective

Common Essential Learnings Foundational Objectives

Learning Objectives


Multiview Drawings


In engineering, various methods are used to represent objects. Among these, the engineering drawing or multiview drawing is a major means of communicating the design concept. In this method, orthogonal projection is used to draw and define an object.

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Orthographic Projection

Later on, you will learn about other methods of representing objects pictorially. Pictorial drawings provide a three dimensional view of an object as it would appear to the observer. Generally, multiview and pictorial drawings are used together to provide a complete picture of the object being represented.


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Pictorial Drawing


Projecting Views


Orthographic projection is the system of representing objects by using more than one view to define the object. There are actually 4 methods of orthographic representation. In this module you will be studying and using the Third-Angle Projection method of representation. Third-Angle Projection is the most widely used method today.

The Third-Angle projection method is an orthographic representation in which the object to be represented and seen by the viewer appears behind the coordinate viewing planes on which the object is orthographically projected.

An easier way to think of this method of projection is to imagine viewing the object and its various views through a glass box. In fact, third-angle projection is sometimes referred to as the glass-box method.

Each face of the box represents one of
the six different planes of projection
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Third Angle (glass-box) Viewing Planes

Using this method, each view is projected onto its respective viewing plane. Each viewing plane is referred to as a plane of projection. The six principal planes of projection are: front, top, bottom, left side, right side, and back. In determining how the particular view will look (on the plane of projection), imagine yourself looking at the object through each side of the glass box.

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Object with Viewing Directions Indicated

View in Direction View From
A Front
B Top
C Left
D Right
E Bottom
F Back

Generally not all of these projections are used in drawings. In determining the number of projections to use, the rule of thumb is include only as many views that are needed to represent the object accurately.

When laying out your various views on your drawing, start with the Principal View. The principal view is the view that shows the most about the product. It is usually the longest view and shows the major shape or profile. Sometimes it may be difficult to determine which view should be used as the principal view. In situations such as this, use your own discretion. This principal view is then designated as the Front View.

After your front view is selected, imagine folding out each flap of the box towards the front view.

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All 6 Orthographic Views Positioned Correctly on Drawing Surface


Hidden Surfaces & Edges


Many objects drawn in engineering contain many features (lines, holes, etc.) that cannot be seen when the object is viewed from a particular angle. These hidden details are normally required on the drawing to show the true shape of the object. Hidden lines are used to illustrate hidden detail.

Hidden lines consist of short, evenly spaced dashes. In CAD, hidden lines are given a different color and are generally assigned to a separate layer.

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How Many Views Do You Need?


Most products require three views to describe them fully. The decision as to the number of views involves a close study of the product. Use enough views to describe all the features and no more. Providing too much information can become confusing to the reader of the drawing.

One View Drawings

There are many products that can be described with one view and a note. A gasket or other thin, flat product can have a note giving the thickness, thus eliminating the need for all views except the front.

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Gasket

Two View Drawings

Products that are symmetrical, conical, or pyramidal in shape can usually be described in two views.

Two View Drawing of a Cap
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Three View Drawings

Most Products require three-view drawings.

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While the front, top, and right side views are most frequently used, any other regular orthographic views could be used instead. In the figure below, the front, right and top views are used.

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More Than Three Views

The designer can use any or all of the six normal orthographic views. The views used must present information that is not clearly shown by the other views. The object below (left) has hidden detail not seen from the front, top, or right. As a result, in addition to the traditional front, top and right views, a bottom view is needed to show the recesses.

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Pictorial View of Object
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Object rotated 180 degrees

4 View Orthographic Projection
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View Spacing &Alignment


For clarity and good appearance, the views should be well balanced on the drawing surface. In determining the alignment and spacing between views, the drafter must consider the size of the object to be drawn, the number of views, the scale of the printed drawing, and the space between views.

When determining the space between drawings, the drafter also needs to allow for the placement of dimensions (to be covered in a later unit).

Indicated below are 3 examples of incorrect spacing or alignment:

Views too close and not centered on page. Inefficient use of space.
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Views too far apart.
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Views not aligned
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Proper spacing and view alignment
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When laying out your views, view alignment is a must. Actually, view alignment is a natural by-product of proper drafting technique (to be demonstrated in the first guided activity in this unit).

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Notice that each view is perfectly aligned with the principal view (Front View).

Spacing, though important, need not be precise but should look balanced. Indicated below is one technique you may find helpful in spacing your views.

e.g. Consider the following drawing.

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Title Block Placement

When creating engineering drawings, the drafter needs to consider title block placement as well. Title blocks are acceptable in any corner of the drawing. When considering their placement, take into account corners of the drawing that are not heavily utilized (to avoid over crowding).

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Sample Projections


Examples of orthographic projection

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Examples of objects having hidden features
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Examples of objects having sloping surfaces
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Examples of objects having circular features
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Activities

Introduction


Everything you need to complete each drawings is provided. You must be precise in the construction of these drawings. All reference points can be derived mathematically. Do not eyeball the placement of anything.

In addition, you will be required to create a Layout for each drawing using the scale indicated for the project. The layout must contain a Title Block indicating: Title, Name, Scale, Units, Date, and Course Name.

You do not need to print a hard copy of the drawing. Only the electronic version will be marked.

Evaluation of your drawings will be based on:

Completeness

Correctness

Accuracy


Activity 4-1
(Guided)


Create a 3 View (Front, Top & Right views) orthographic projection of the following object. In addition, create a layout (scale 1:1) with title block.

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Units: inches

 


Activity 4-2


Create a 3 View (Front, Top & Right views) orthographic projection of the following object. In addition, create a layout (scale 1:1) with title block.

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Units: mm

Save the drawing as "mv2" (multiview) inside your Unit4 folder.


Activity 4-3


Create a 3 View (Front, Top & Right views) orthographic projection of the following object. In addition, create a layout (scale 1:1) with title block.

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Units: inches

Save the drawing as "mv3" (multiview) inside your Unit4 folder.


Activity 4-4


Create a 3 View (Front, Top & Right views) orthographic projection of the following object. In addition, create a layout (scale 1:1) with title block.

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Units: mm

Save the drawing as "mv4" (multiview) inside your Unit4 folder.