• Engineering drawing

    Engineering drawing

    • An engineering drawing, a type of technical drawing, is used to fully and clearly define requirements for engineered items.

      Engineering drawing (the activity) produces engineering drawings (the documents). More than merely the drawing of pictures, it is also a language—a graphical language that communicates ideas and information from one mind to another. Most especially, it communicates all needed information from the engineer, who designed a part, to the workers, who will make it.

      Engineering drawing and artistic drawing are both types of drawing, and either may be called simply "drawing" when the context is implicit. Engineering drawing shares some traits with artistic drawing in that both create pictures. But whereas the purpose of artistic drawing is to convey emotion or artistic sensitivity in some way (subjective impressions), the purpose of engineering drawing is to convey information (objective facts). One of the corollaries that follows from this fact is that, whereas anyone can appreciate artistic drawing (even if each viewer has his own unique appreciation), engineering drawing requires some training to understand (like any language); but there is also a high degree of objective commonality in the interpretation (also like other languages). In fact, engineering drawing has evolved into a language that is more precise and unambiguous than natural languages; in this sense it is closer to a programming language in its communication ability. Engineering drawing uses an extensive set of conventions to convey information very precisely, with very little ambiguity. Engineering drawing is a type of technique which is used to fully and clearly defined requirements for engineered items. Engineering drawing is one of the best way to communicate one idea easily to other person.

      The process of producing engineering drawings, and the skill of producing those, is often referred to as technical drawing or drafting although technical drawings are also required for disciplines that would not ordinarily be thought of as parts of engineering (such as architecture, landscaping, cabinet making, and garment-making).

      Persons employed in the trade of producing engineering drawings were called draftsmen (or draughtsmen) in the past. Although these terms are still in use, the non-gender-specific terms draftsperson and drafter are now more common.

      • Geometry – the shape of the object; represented as views; how the object will look when it is viewed from various angles, such as front, top, side, etc.
      • Dimensions – the size of the object is captured in accepted units.
      • Tolerances – the allowable variations for each dimension.
      • Material – represents what the item is made of.
      • Finish – specifies the surface quality of the item, functional or cosmetic. For example, a mass-marketed product usually requires a much higher surface quality than, say, a component that goes inside industrial machinery.
      • 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.
      • 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 pencil.
      • Type C lines are used for breaks when the whole object is not shown. These are freehand drawn and only for short breaks. 2H pencil
      • Type D lines are similar to Type C, except these are zigzagged and only for longer breaks. 2H pencil
      • Type E lines indicate hidden outlines of internal features of an object. These are dotted lines. 2H pencil
      • Type F lines are Type F[typo] lines, except these are used for drawings in electrotechnology. 2H pencil
      • Type G lines are used for centre lines. These are dotted lines, but a long line of 10–20 mm, then a 1 mm 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. These 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. These are drawn with a long line of 10-
      • In first-angle projection, the projectors originate as if radiated from a viewer's eyeballs and shoot through the 3D object to project a 2D image onto the plane behind it. The 3D object is projected into 2D "paper" space as if you were looking at a radiograph of the object: the top view is under the front view, the right view is at the left of the front view. First-angle projection is the ISO standard and is primarily used in Europe.
      • In third-angle projection, the projectors originate as if radiated from the 3D object itself and shoot away from the 3D object to project a 2D image onto the plane in front of it. The views of the 3D object are like the panels of a box that envelopes the object, and the panels pivot as they open up flat into the plane of the drawing. Thus the left view is placed on the left and the top view on the top; and the features closest to the front of the 3D object will appear closest to the front view in the drawing. Third-angle projection is primarily used in the United States and Canada, where it is the default projection system according to ASME standard ASME Y14.3M.
      • it projects an image by intersecting parallel rays (projectors)
      • from the three-dimensional source object with the drawing surface (projection plan).
      • Smaller as their distance from the observer increases
      • Foreshortened: the size of an object's dimensions along the line of sight are relatively shorter than dimensions across the line of sight.
      • Drawing title (hence the name "title block")
      • Drawing number
      • Part number(s)
      • Name of the design activity (corporation, government agency, etc.)
      • Identifying code of the design activity (such as a CAGE code)
      • Address of the design activity (such as city, state/province, country)
      • Measurement units of the drawing (for example, inches, millimeters)
      • Default tolerances for dimension callouts where no tolerance is specified
      • Boilerplate callouts of general specs
      • Intellectual property rights warning
      • Black = object line and hatching
      • Red = hidden line
      • Blue = center line of piece or opening
      • Magenta = phantom line or cutting plane line
      • Basant Agrawal and C M Agrawal (2013). Engineering Drawing. Second Edition, McGraw Hill Education India Pvt. Ltd., New Delhi. [1]
      • Paige Davis, Karen Renee Juneau (2000). Engineering Drawing
      • David A. Madsen, Karen Schertz, (2001) Engineering Drawing & Design. Delmar Thomson Learning. [2]
      • Cecil Howard Jensen, Jay D. Helsel, Donald D. Voisinet Computer-aided engineering drawing using AutoCAD.
      • Warren Jacob Luzadder (1959). Fundamentals of engineering drawing for technical students and professional.
      • M.A. Parker, F. Pickup (1990) Engineering Drawing with Worked Examples.
      • Colin H. Simmons, Dennis E. Maguire Manual of engineering drawing. Elsevier.
      • Cecil Howard Jensen (2001). Interpreting Engineering Drawings.
      • B. Leighton Wellman (1948). Technical Descriptive Geometry. McGraw-Hill Book Company, Inc.
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    • Engineering drawing