1 What is a sectional view and why is it necessary to draw s

1.      What is a sectional view and why is it necessary to draw sectional views?

2.      Define an auxiliary view and explain why a designer would select an auxiliary view in addition to regular view?

3.      Explain how an isometric projection differs from an oblique projection?

Solution

1.

INTRODUCTION

In engineering drawing, various objects have invisible or hidden interior features, which are represented by dotted lines in their projection views. But, when the features, are too many, the orthographic projections obtained get complicated and difficult to understand. In order to understand the interior view details, the object is cut an imaginary cutting plane called Sectional Plane. The part of the object between the cutting plane and the observer is assumed to be removed and view is then shown in section. The view thus obtained is called Sectional View.

The view obtained by cutting an object with an imaginary cutting plane is called Sectional View.

The surface produced by cutting the object by the section plane is called Section. It is indicated by thin section lines uniforemly spaced, generally at an angle of 45\'. As already imagined, a sectional view is a view seen when a portion of the object nearest to the observer is imagined to be removed by means of a cutting plane or planes, thus revealing the interior construction. The other views are not affected in any way always represent the entire object.

The sectional views are of mainly two types. These are dependent upon the number of cutting planes cutting the object.

NECESSITY OF SECTIONAL VIEWS:

Actually the sectional view showa and elaborates the internal construction of a machine, so that the drawing shows the components and parts that a machine consists of.

Actually the sectional view is an \"anatomy\" study of a machine. Designers use these view to establish a machine from scratch, and to modify the design of a machine.

When you become a designer, how can you design an assembled system of mechanical components ? certainly using one or more sectional views.

And for the second question, yes we could draw a sectional view in either way, but actually we do not need to. We just need the sectional view as it is to show and elaborate the internal construction. Orthographic and other views are artistic views not needed in mechanical design.

2. An auxiliary view is an orthographic view which is projected onto any plane other than the frontal, horizontal, or profile plane. An auxiliary view is not one of the six principal views. One of the principle reasons for drawing auxiliary views is to show a surface at true size and shape. This is the reason why engineers select auxiliary view in addition to regular view.

3.

An isometric projection is a technical way of representing an object in three dimensions and may include several oblique views of the object. It\'s used extensively in engineering and manufacturing to provide an accurate and detailed view of how an object is designed or put together.

Isometric drawings employ a modified type of perspective in which all sides are equally foreshortened, but without the use of converging lines (I.e., all planes are parallel to each other).

An isometric projection may be done with any number of values to enhance its three-dimensional appearance. Several wireframe views usually accompany it to show the front, top and bottom of the object from oblique angles.

An oblique view will always show the object as being perfectly flat with respect to the picture plane (I.e., that particular face of the object will have only two dimensions from the viewer\'s point of view).