Posted in Engineering Drawing

Method of Dimensioning & Arrangement of Dimensions

An engineering drawing, besides illustrating the shape of an object, must also show the size and any other relevant details essential for the construction of the object. Indicating on a drawing, the sizes of the object and other details essential for its construction and function using lines, numerals, symbols, notes, etc., is called dimensioning. The dimensions are given to indicate the sizes of various features of the object and their locations. Indicated dimensions of an object should not be mistaken as those which are required to make the drawing. The dimensions indicated on engineering drawings are those which are essential…

Posted in Engineering Drawing

Engineering Drawing Projection and Views

Introduction Engineers are confronted with the task of communicating the design, development and structures of machines to manufacturers and builders. The shape and size of various parts of a machine and its structure must be recorded on plane sheets in a systematic way for communication. The pictorial view of the object does not carry all the details, especially the inner details and correct shape of complicated parts. Different methods, therefore, are implied for describing the exact shape based on the ‘projectors’ drawn by engineers. Principle of Projection If straight lines are drawn from various points on the contour of an…

Posted in Engineering Drawing

Difference Between Engineering Drawing and Workshop Drawing

Introduction Engineering drawing is a language which is understood throughout the world by engineers and fabricators. Other languages may fail to describe the size, shape, physical aspects, inner details, finish, etc., but the engineers’ language known as ‘Engineering Drawing’ never fails. The most intricate assemblies with their various complicated parts can be easily represented by engineering graphics. There are various types of engineering drawings and all have one simple purpose, i.e.  the communication of ideas to others. The drawings used for communicating the ideas of the design engineer to the production engineer and technicians is known as ‘Workshop Drawing’. Engineering…

Posted in Engineering Drawing

Dimensioning and Layout Procedure in Engineering Drawing

Introduction A drawing of an object is prepared to define its shape and to specify its size. The shape description is based on projection and the size description on dimensioning.  Every drawing must give its complete size description stating length, width, thickness, diameter of holes, grooves, angles, etc. and such other details relating to its construction. To give all those measurements and information describing the size of the object in the drawing is called dimensioning. Placing of Dimensions Dimensions should be placed on the view, which shows the relevant features most clearly. The two recommended systems of placing the dimensions…

Posted in Engineering Drawing

Standard Conventions & Abbreviations Used in Engineering Drawing

Introduction Conventions make the drawing simple and easy to draw. But it is difficult for untrained eyes to understand it easily. Drafting time should be reduced to cut drafting cost. Time must be saved in drafting. It will take a lot of time to draw the actual shape, hence, some conventions are standardized and used in the drawing to save the time. In 1935 the American Standard Association issued the first American standards, entitled “Drawing and Drafting Room Practice”.  These standard advocated conventions in many ways, e.g. partial views, half views, symbols, lettering, lines, hatching lines, etc. These have been…

Posted in Engineering Drawing

Lettering Styles Used in Engineering Drawing

Introduction Writing of titles, dimensions, notes, and other important particulars on a drawing is called lettering. Lettering is an important part of a drawing. However accurate and neat a drawing may be drawn, its appearance is spoiled and sometimes, its usefulness is impaired by poor lettering.  Lettering should, therefore, be done properly in clear, legible and uniform style. It should be in plain and simple style so that it could be done free hand and speedily. Style of Lettering There are various forms of alphabets used in the art of lettering and each type is used for some particular purpose….

Posted in Engineering Drawing

Application of Geometry in Engineering Drawing

Introduction Engineering drawing is the application of the principles and methods of geometry.  Without the knowledge of geometry, it is difficult to prepare a drawing. All drawings have points, lines and angles. Geometrical drawing is the foundation of all engineering drawing. Accuracy, neatness and legibility are of great importance in engineering drawing. Geometrical drawing is the art of representation of geometrical objects such as square, rectangle, cube, cylinder, cone, sphere, etc. Geometrical drawing consists of: Plane Geometrical Drawing. It is the representation of objects on a drawing sheet, having two dimensions, i.e. length, breadth and radius such as square, rectangle,…

Posted in Engineering Drawing

Complete List of Instruments Used for Diagrams in Engineering Drawing

Introduction Engineering drawing is the language of engineers and technicians. The accuracy and neatness of engineering drawing depends on the quality of the instruments used.  With good instruments, the drawing can be prepared easily, quickly and accurately.  Therefore, the knowledge of different drawing instruments and materials, methods of using them and the preparatory works to be completed before commencing the drawing is very important. Instruments for Drawing The following drawing instruments are required for preparing a neat and correct drawing. (a) Basic Instruments (i) Drawing board (ii) Drawing sheet (iii) Drawing pencil (iv) Drawing clips or pins (v) Eraser (vi)…

Posted in Engineering Drawing

Introduction To Engineering Drawing

Introduction A drawing is a graphic representation of a real thing. To draw something as a figure by means of lines expressing some ideas on the paper is known as a drawing. The purpose of the drawing is to define and specify the shape and size of a particular object by means of lines and other information about the object. A good drawing gives full information about the object in the shortest and simplest way. A drawing worked out by an engineer, having engineering ideas, for engineering purpose, is known as Engineering Drawing. It is the universal graphic language of…

Posted in Engineering Drawing

Orthographic Projections

Introduction In the preceding chapters 1 to 4 plane geometry, where the constructions of the geometrical figures having only two dimensions are discussed, solid geometry is delt with in the following chapters. Engineering drawing, particularly solid geometry is the graphic language used in the industry to record the ideas and information necessary in the form of blue prints to make machines, buildings, structures etc., by engineers and technicians who design, develop, manufacture and market the products. Projection As per the optical physics, an object is seen when the light rays called visual rays coming from the object strike the observer’s…