EDP

• Engineering drawing – is a two dimensional representation of three dimensional objects. In

  general, it provides necessary information about the shape, size, surface quality, material, manufacturing process, etc., of the object. It is the graphic language from which a trained person can visualize objects.
• The Instruments and other aids used in drafting work are listed below:

  ➢ Drawing board

  ➢ Set squares

  ➢ French curves

  ➢ Templates

  ➢ Mini drafter

  ➢ Instrument box

  ➢ Protractor

  ➢ Set of scales

  ➢ Drawing sheets

  ➢ Pencils
• Drawing Board-Until recently drawing boards used are made of well seasoned softwood of about 25 mm thick with a working edge for T-square. Nowadays

  mini-drafters are used instead of T-squares

  which can be fixed on any board. The standard

  size of board depends on the size of drawing

  sheet size required.
• Mini Drafter- consists of an angle formed by two

  arms with scales marked and rigidly hinged to

  each other .It combines the functions of T-square,

  set-squares, scales and protractor. It is used for

  drawing horizontal, vertical and inclined lines,

  parallel and perpendicular lines and for measuring

  lines and angles.
• Instrument Box

  Instrument box contains :

  1. Compass

  2. Shapes and rulers

  3. Technical pens
• What is important is the position of the pencil lead with respect to the tip of the compass. It should be at least 1 mm above as shown in the fig. because the tip oes into the board for grip by 1 mm.
• Pencils-

  Pencils with leads of different degrees of hardness or grades

  are available in the market. The hardness or softness of the

  lead is indicated by 3H, 2H, H, HB, B, 2B, 3B, etc. The grade

  HB denotes medium hardness of lead used for general

  purpose. The hardness increases as the value of the numeral
• ➢ HB Soft grade for Border lines, lettering and free

  sketching

  ➢ H Medium grade for Visible outlines, visible

  edges and boundary lines

  ➢ 2H Hard grade for construction lines, Dimension

  lines, Leader lines, Extension lines, Centre lines,

  Hatching lines and Hidden lines.
• Drawing Sheets- is a white paper on which an object is

  drawn which is available in various sizes. The sheet used

  for engineering should be of good quality. It should be

  white in color with uniform thickness with must resist the

  easy torn of paper.
• Title Block- should lie within the drawing space at the bottom or at the right side of the drawing sheet providing the following information.

  ➢ Title of the drawing.

  ➢ Drawing number.

  ➢ Scale.

  ➢ Name of the firm, and

  ➢ Initials of staff, who have

  designed, checked and

  approved.
• Lines- In Engineering Graphics, the details of various objects are drawn by different types of lines. Each line has a definite meaning and sense to convey.
• DRAWING ANNOTATIONS

  1. Dimension lines and leaders

  2. Drawing

  3. Drawing Tags/ Marks and Drawing Title View
• Reducing Scale


  A scale of the reduction ratio, which is generally a fraction, used when the dimensions of large objects must be reduced to accommodate on a standard size drawing sheet
• Drawing scale


  • Represent something at a size other than their full size
  • Can represent things at either a large or a smaller scale than full size, depending on the size of the thing they are representing and the use to which the drawing will be put
• Drawing scale

  1. Illustrate items that it is not useful or convenient to draw at their actual size

  2. Drawing the item at full size would be unmanageable

  3. Drawing the item at full size would not easily fit on a single sheet of paper (such as building)

  4. Items need to be draws larger than adequately represent all the detail that needs to be communicated
• PHILIPPINE STANDARD UNIT OF MEASUREMENTMETRIC

  ➢ A number of units of measurement were used in the

  Philippines to measure variety of quantities including

  mass, are, and capacity. The metric system has been

  compulsory in the country since 1860, during the late

  Spanish colonial period. A mixture of Spanish units and

  indigenous units were used alongside American units in

  1900s
• Geometric Construction- is a procedure for drawing figures

  and shapes that requires only the tools of drafting, including

  traditional drawing instruments and equipment and the new

  tools of computer hardware and software. Regardless of the

  tools, geometric construction requires an understanding of

  geometric shapes and the mechanics of their construction, as

  well as the ability to solve problems visually.
• Geometric Construction-

  Emphasizes scale, uniformity of line works, and mooch

  joining of lines and curves when done manually including

  parallel lines, perpendicular lines, angles, circles, polygon,

  tangencies, tangent arcs, curves, conics, involutes,

  spirals, and helices
• Geometric Construction

  Objectives:Identify and specify basic geometric elements and

  primitive shapes.

  b. Select a 2D profile that best describes the shape of

  an object

  c. Identify mirrored shapes and sketch their lines of

  symmetry.
• Geometric Construction

  Objectives:

  1. Identify and specify basic geometric elements and

  primitive shapes.

  b. Select a 2D profile that best describes the shape of

  an object

  c. Identify mirrored shapes and sketch their lines of

  symmetry.

  d. Identify shapes that can be formed by extrusion and

  sketch their across sections.

  e. Identify shapes that can be formed by revolution

  techniques and sketch their profiles.

  f. The usage of drafting tools.
• PROJECTIONS OF PLANES

  • A plane of projection (i.e., an image or picture plane) is an

  imaginary flat plane upon which the image is

  projected. The projection is produced by connecting the points

  where the lines of sight pierce the

  projection plane. As a result, the 3D object is transformed into

  a 2D view.
• Orthographic View - If the distance from the observer to the

  object is infinite, then the projection lines are assumed to be

  parallel, and the projection is called a parallel projection.

  Parallel projection is orthographic if the plane of projection is

  placed

  between the observer and the object, and the plane is

  perpendicular to the parallel lines of sight.
• Multiview projections


  Projections of an object from multiple viewpoints
• Plane of projection


  • Can be oriented to produce an infinite number of views of an object
  • The most common views are the six mutually perpendicular views
• main principles of creating multiview projections

  • Front view
  • Left side view
  • Right side view
  • Top view
  • Bottom view
  • Rear view
• Front view


  The one that shows most features or characteristics
• Left side view


  Shows what becomes the left side of the object after establishing the front view position
• Right side view


  Shows what becomes the right side of the object after establishing the front view position
• Top view


  Shows what becomes the top of the object once the position of the front view is established
• Bottom view


  Shows what becomes the bottom of the object once the position of the front view is established
• Rear view


  Shows what becomes the rear of the object once the position of the front view is established
• Conventional view placement


  Generally, three views of an object are enough, however, a drawing must contain as many views as necessary to illustrate the part, usually at right angles to one another
• Frontal plane of projection


  • In Multiview projection, the object is viewed perpendicular to the main faces, so that only one face of the object is depicted in each view
  • The frontal plane of projection is the plane onto which the front view of a multiview drawing is projected
• Front view


  In the front view you can see height and width of the object, but you cannot see its depth
• Horizontal plane of projection


  • The top view is projected onto the horizontal plane of projection, which is plane suspended above and parallel to the top of the object
  • The top view of an object shows the width and depth dimensions
• Right side and left side view


  • The right side view is the standard side view, projected onto the right profile plane of projection, which is a parallel to the right side of the object
  • You can also use the left side view if it is more descriptive and informative
  • The side view of an object shows the depth and height dimensions
• Three-view multiview

  is the standard used in engineering and technology, because often the other three common views are mirror images and do not add to the knowledge about the object
• Building Symbols- All engineering drawings include a

  particular way of representation. The representation can be

  done by using specific symbols representing the element to be

  built in that particular place or area. These symbols provide a

  visual model of the structure to be constructed.
• Architectural Symbols:

  Like other engineering drawings, Architecture drawings

  also include some symbols

  that help give an easy presentation of the project to nontechnical

  persons or clients.

  These architectural symbols are necessary and must be

  included in the architectural

  drawing as they are easy to understand.
• LEVEL OF DESIGN (LOD) DRAWINGS : TRADITIONAL