Ed ass 2013


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Ed ass 2013

  2. 2. Table of ContentsTable of Contents ...........Error! Bookmark not defined.Introduction ..................Error! Bookmark not defined.Engineering Drawing (used in communication) ............. 2Orthographic Projection ....................................... 5Type of Lines used in Engineering Drawing ................. 6Pictorial Drawing ................................................ 8 Isometric Projection .......................................... 8 Oblique Projection ............................................ 9 Perspective Projection ..................................... 11Conclusion...................................................... 12MD.KHAIRUL SYAHRUDDIN, MRE C Page 2
  3. 3. Introduction An engineering drawing is a type of technical drawing and as well as agraphical language used by those concerned with the constructive arts: in themanufacturing of machinery, structure, ships, aircraft and so on. Engineeringdrawings are often referred to as “blueprints” or “blue lines”. It is used to fullyand clearly define requirements for engineered items and is usually created inaccordance with standardized conventions for layout, nomenclature,interpretation, appearance, size and etc. Its purpose is to accurately and unambiguously capture all the geometricfeatures of a product or a component. The end goal of an engineering drawing is toconvey all the required information that will allow a manufacturer to produce aspecific component. In short, student like us has not only to write the language butalso to read it. To ensure uniformity of interpretation the methods adopted forpreparation of drawings have been standardized through various standards.Find google, introduction of engineering drawingMD.KHAIRUL SYAHRUDDIN, MRE C Page 3
  4. 4. 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 asconvergent 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 ormulti view projection sufficiently separate projection types in to those used forengineering working drawings (orthographic) and those used for display (architecturalrendering, technical illustrations etc.) In short, one of the best ways to communicate ones ideas is through some form ofpicture or drawing. This is especially true for the engineer. The purpose of this chapter isto give you the basics of engineering sketching and drawing. We will treat "sketching" and"drawing" as one. "Sketching" generally, means freehand drawing. "Drawing" usually, meansusing drawing instruments, from compasses to computers to bring precision to thedrawings.MD.KHAIRUL SYAHRUDDIN, MRE C Page 4
  5. 5. Orthographic Projection Orthographic projection is the representation of a three-dimensional component ona flat surface (the drawing sheet) in two dimensional forms. This consists of a set of twoor more separate views of component taken from different directions, generally at rightangle to each other and arranged relative to each other in a definite way. Two methods ofOrthographic Projection are used, First-angle projection and Third-angle projection.However, three views are shown in order to clarify internal and external detail. The viewsare 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 plan view is ABOVE the front view. The right-hand side view is on the left- The right-hand side view is on the right- hand side of the front view. hand side of the front view. The left-hand side view is on the right- The left-hand side view is on the left-hand hand side of the front view. side of the front view.MD.KHAIRUL SYAHRUDDIN, MRE C Page 5
  6. 6. Type of Lines used in Engineering DrawingA variety of line styles graphically represent physical objects. Types of lines include thefollowing: 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.MD.KHAIRUL SYAHRUDDIN, MRE C Page 6
  7. 7. Lines can also be classified by a letter classification in which each line is given aletter. 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.MD.KHAIRUL SYAHRUDDIN, MRE C Page 7
  8. 8. Pictorial DrawingEvery person cannot understand the orthographic projection. Its execution requires athorough understanding of the principles of projection and its reading requires a goodpractice of constructive imagination. We can describe the shape of a job by means ofpictorial drawing also, which can be understood quite easily. Pictorial drawing is thedrawing of a picture in graphic language of engineers, to represent a real thing by meansof picture views. It shows the appearance of the object by one view only. Following threemethods of pictorial projections are commonly used in engineering drawing:(a) Isometric projection(b) Oblique projection(c) Perspective projection Isometric, Oblique and Perspective DrawingMD.KHAIRUL SYAHRUDDIN, MRE C Page 8
  9. 9. ISOMETRIC PROJECTIONA trained eye and good imagination will be able to understand the three dimensions of anobject. Several orthographic views on different planes are to be drawn to understand fullyan object. But in isometric projection, only one view on a plane is sufficient to representan object in its realistic appearance. Anyone can understand by looking at a view what thejob is by isometric projection. Isometric ProjectionIsometric projection is a type of pictorial projection. Isometric means equal measure. Inthis isometric projection, all the plane surfaces and the edges formed of these planesurfaces should be equally inclined to the metric plane. Metric plane is the samehorizontal 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 referenceline (horizontal line) and the three axes (X, Y Z) are drawn by taking an angle of 30° fromthe reference horizontal line as drawn in Fig 7.2. Z axis is a vertical line to the horizontalline drawn from intersection point of X and Y axes.MD.KHAIRUL SYAHRUDDIN, MRE C Page 9
  10. 10. 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 isometricprojection, in oblique projection, one side of the object is horizontal, second side isvertical and the third side is inclined at 30Oor 45O to the horizontal. The lengths of thehorizontal and vertical sides are equal to the actual lengths, but the length of the inclinedside 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 verticalplane of projection and the visual rays parallel to each other pierce the plane ofprojection obliquely (Oblique means inclined). The projection represents the front face ofthe object in its true shape and size. The rest of the object is not projected true in itsshape and size. Both the isometric and oblique projections are the methods ofrepresenting the object pictorially. But the oblique projection is preferable to theisometric projection in representing the objects of circular shapes, because the front faceis in actual shape and size. It is not distorted. Oblique Projection O O Third Axis of the Oblique Projection may be Inclined at 30 or 45MD.KHAIRUL SYAHRUDDIN, MRE C Page 10
  11. 11. Inclination of Inclined Axis Oblique projection of a cubePerspective Projection Perspective projection or perspective drawing is the representation of an object ona plane surface, called the picture plane, as it would appear to the eye, when viewedfrom a fixed position. It may also be defined as the figure formed on the picture planewhen visual rays from the eye to the object cut the picture plane. Perspective is mainlyused in architecture. By means of perspective, the architecture is able to show how anobject would appear when constructed.MD.KHAIRUL SYAHRUDDIN, MRE C Page 11
  12. 12. ConclusionWith my skills and what I have studied about engineering so far, I havefinished all the drawings given neat and clean. I also did research on theinternet to look for more information about engineering drawing. I used allmy engineering materials such as pencils, tee-rule, Set Square, compass,drawing board and etc. It is a good engineering practice to review what wehave studied before, there were so many difficulties, but in the end Iencountered the problems through more research since we were given lotsof time.MD.KHAIRUL SYAHRUDDIN, MRE C Page 12