ed ass 2013

بلقيهجفريکجروترأنمکتبMAKTAB KEJURUTERAAN JEFRI BOLKIAH

KUALA BELAITNEGARA BRUNEI DARUSSALAM

ASSIGNMENT 1SESSION 2012/2014

Please Tick ( ) First Attempt: Re-Do:

TITLE: ENGINEERING DRAWING FUNDAMENTAL,GEOMETRICAL CONSTRUCTION,

ORTHOGRAPHIC & PICTORIAL PROJECTIONS AND PATERN DEELOPMENT

UNIT TITLE: ENGINEERING DRAWING

NAME/ID CARD NUMBER: Abd Ammar Ar-rasyid bin Razali(01-061196)

GROUP/LEVEL: Diploma Year 1 Marine Engineering (A)

DATE GIVEN: 2013 DATE SUBMITTED:

MD.KHAIRUL SYAHRUDDIN, MRE C

Table of ContentsTable of Contents...................................................1

Introduction............................................................2

Engineering Drawing (used in communication)......3

Orthographic Projection..........................................4

Type of Lines used in Engineering Drawing............5

Pictorial Drawing....................................................7

Isometric Projection..............................................8

Oblique Projection................................................9

Perspective Projection........................................10

Conclusion............................................................11


IntroductionAn engineering drawing is a type of technical drawing and as well as

a graphical language used by those concerned with the constructive arts: in the manufacturing of machinery, structure, ships, aircraft and so on. Engineering drawings are often referred to as “blueprints” or “blue lines”. It is used to fully and clearly define requirements for engineered items and is usually created in accordance with standardized conventions for layout, nomenclature, interpretation, appearance, size and etc.

Its purpose is to accurately and unambiguously capture all the geometric features of a product or a component. The end goal of an engineering drawing is to convey all the required information that will allow a manufacturer to produce a specific component. In short, student like us has not only to write the language but also to read it. To ensure uniformity of interpretation the methods adopted for preparation of drawings have been standardized through various standards.

Find google, introduction of engineering drawing


Engineering Drawing (used in communication)

All forms of engineering and technical work require that a two dimensional surface (paper) be used to communicate ideas and the physical description of a variety of shapes. Here projections have been divided in to two basic categories; pictorial and multi view. This simple division separates single view projections (oblique, perspective and isometric) from multi view projections (orthographic). Theoretically, projections can be classified as convergent and parallel, or divided in to three systems of projection: perspective, oblique, and orthographic. Division of types based on whether the drawing is a one view or multi view projection sufficiently separate projection types in to those used for engineering working drawings (orthographic) and those used for display (architectural rendering, technical illustrations etc.)

In short, one of the best ways to communicate one's ideas is through some form of picture or drawing. This is especially true for the engineer. The purpose of this chapter is to give you the basics of engineering sketching and drawing. We will treat "sketching" and "drawing" as one. "Sketching" generally, means freehand drawing. "Drawing" usually, means using drawing instruments, from compasses to computers to bring precision to the drawings.


Orthographic Projection

Orthographic projection is the representation of a three-dimensional component on a flat surface (the drawing sheet) in two dimensional forms. This consists of a set of two or more separate views of component taken from different directions, generally at right angle to each other and arranged relative to each other in a definite way. Two methods of Orthographic Projection are used, First-angle projection and Third-angle projection. However, three views are shown in order to clarify internal and external detail. The views are known as:

FRONT VIEW TOP VIEW SIDE VIEW (left and/or right hand view) (And at times) BASE/SECTIONAL VIEWS

A comparisons of first angle projection and third angle projection

First angle Third angle The plan is BELOW the front view. The right-hand side view is on the

left-hand side of the front view. The left-hand side view is on the

right-hand side of the front view.

The plan view is ABOVE the front view. The right-hand side view is on the

right-hand side of the front view. The left-hand side view is on the left-

hand side of the front view.

Type of Lines used in Engineering Drawing


A variety of line styles graphically represent physical objects. Types of lines include the following:

Visible – are continuous lines used to depict edges directly visible from a particular angle.

Hidden – are short-dashed lines that may be used to represent edges that are not directly visible.

Center – are alternately long- and short-dashed lines that may be used to represent the axes of circular features.

Cutting plane – are thin, medium-dashed lines, or thick alternately long- and double short-dashed that may be used to define sections for section views.

section – are thin lines in a pattern (pattern determined by the material being "cut" or "sectioned") used to indicate surfaces in section views resulting from "cutting." Section lines are commonly referred to as "cross-hatching."

Phantom - (not shown) are alternately long- and double short-dashed thin lines used to represent a feature or component that is not part of the specified part or assembly. E.g. billet ends that may be used for testing, or the machined product that is the focus of a tooling drawing.

Lines can also be classified by a letter classification in which each line is given a letter.


Type A lines show the outline of the feature of an object. They are the thickest lines on a drawing and done with a pencil softer than HB.

Type B lines are dimension lines and are used for dimensioning, projecting, extending, or leaders. A harder pencil should be used, such as a 2H.

Type C lines are used for breaks when the whole object is not shown. They are freehand drawn and only for short breaks. 2H pencil

Type D lines are similar to Type C, except they are zigzagged and only for longer breaks. 2H pencil

Type E lines indicate hidden outlines of internal features of an object. They are dotted lines. 2H pencil

Type F lines are Type F[typo] lines, except they are used for drawings in electro technology. 2H pencil

Type G lines are used for Centre lines. They are dotted lines, but a long line of 10–20 mm, then a gap, then a small line of 2 mm. 2H pencil

Type H lines are the same as Type G, except that every second long line is thicker. They indicate the cutting plane of an object. 2H pencil

Type K lines indicate the alternate positions of an object and the line taken by that object. They are drawn with a long line of 10–20 mm, then a small gap, then a small line of 2 mm, then a gap, then another small line. 2H pencil.


Pictorial Drawing

Every person cannot understand the orthographic projection. Its execution requires a thorough understanding of the principles of projection and its reading requires a good practice of constructive imagination. We can describe the shape of a job by means of pictorial drawing also, which can be understood quite easily. Pictorial drawing is the drawing of a picture in graphic language of engineers, to represent a real thing by means of picture views. It shows the appearance of the object by one view only. Following three methods of pictorial projections are commonly used in engineering drawing:

(a) Isometric projection (b) Oblique projection (c) Perspective projection

Isometric, Oblique and Perspective Drawing


ISOMETRIC PROJECTIONA trained eye and good imagination will be able to understand the three dimensions of an object. Several orthographic views on different planes are to be drawn to understand fully an object. But in isometric projection, only one view on a plane is sufficient to represent an object in its realistic appearance. Anyone can understand by looking at a view what the job is by isometric projection.

Isometric Projection

Isometric projection is a type of pictorial projection. Isometric means equal measure. In this isometric projection, all the plane surfaces and the edges formed of these plane surfaces should be equally inclined to the metric plane. Metric plane is the same horizontal plane which is used in orthographic projection.

To represent the three dimensions (length, breadth and height) of the object, there are three axes known as ISOMETRIC AXES. To start an isometric drawing, a reference line (horizontal line) and the three axes (X, Y Z) are drawn by taking an angle of 30° from the reference horizontal line as drawn in Fig 7.2. Z axis is a vertical line to the horizontal line drawn from intersection point of X and Y axes.


OBLIQUE PROJECTIONOblique projection may be illustrated in different ways, according to the choice of axes, length of inclined side and direction of looking the side. As compared with isometric projection, in oblique projection, one side of the object is horizontal, second side is vertical and the third side is inclined at 30Oor 45O to the horizontal. The lengths of the horizontal and vertical sides are equal to the actual lengths, but the length of the inclined side is taken as three-fourth or half of the actual length.

In oblique projection, an object is placed with its front face parallel to a vertical plane of projection and the visual rays parallel to each other pierce the plane of projection obliquely (Oblique means inclined). The projection represents the front face of the object in its true shape and size. The rest of the object is not projected true in its shape and size. Both the isometric and oblique projections are the methods of representing the object pictorially. But the oblique projection is preferable to the isometric projection in representing the objects of circular shapes, because the front face is in actual shape and size. It is not distorted.

Oblique Projection

Third Axis of the Oblique Projection may be Inclined at 30O or 45O


Inclination of Inclined Axis Oblique projection of a cube

Perspective ProjectionPerspective projection or perspective drawing is the representation of an

object on a plane surface, called the picture plane, as it would appear to the eye, when viewed from a fixed position. It may also be defined as the figure formed on the picture plane when visual rays from the eye to the object cut the picture plane. Perspective is mainly used in architecture. By means of perspective, the architecture is able to show how an object would appear when constructed.


Conclusion

With my skills and what I have studied about engineering so far, I have finished all the drawings given neat and clean. I also did research on the internet to look for more information about engineering drawing. I used all my engineering materials such as pencils, tee-rule, Set Square, compass, drawing board and etc. It is a good engineering practice to review what we have studied before, there were so many difficulties, but in the end I encountered the problems through more research since we were given lots of time.


ed ass 2013

Documents

view ormulti view projection

plan view

pictorial drawing

drawing sheet

freehand drawing

oblique projection

perspective projection

type of technical drawing