Drawing Standards and Scales Quiz

Type X (A0~A4)

• Type X refers to the sheet sizes A0 through A4.
• The minimum border width "c" is 10mm for all sizes except A1 and A0, where it is 20mm.
• The minimum border width "d" is 25mm for all sheet sizes.
• The drawing space is the area within the borders.
• The title block should be placed below the drawing space.

Type Y (A4 only)

• Type Y refers to specific drawing requirements for A4 sheet size only.
• The title block is placed below the drawing space.

Drawing Scales : Definition

• Scale is the ratio between the linear dimension of a drawn representation of an object and the actual object.
• Drawing scale is commonly found in the title block.

Drawing Scales : Designation

• Designating a scale consists of the word "SCALE" followed by its ratio.
• For full-size drawings, the scale is "SCALE 1:1”.
• For enlarged drawings, the scale is "SCALE X:1" where X is greater than 1.
• For reduced drawings, the scale is "SCALE 1:X" where X is greater than 1.

Drawing Scales : Notes

• Dimension numbers shown in a drawing represent the true size of an object, independent of the drawing scale used.

Drawing Scales : Standard scales

• Standard reducing scales are: 1:2, 1:5, 1:10, 1:20, 1:50, 1:100
• Standard enlarging scales are: 2:1, 5:1, 10:1, 20:1, 50:1, 100:1

Lettering : Recommendation

• Text on drawings should have uniform shape, size (text height), and thickness of stroke, with appropriate space between letters and words.

Lettering : Style (this course)

• Gothic vertical style.
• Begin the sentence, phrase, or word with a capital letter.
• Text height should be 2-3 mm.
• Spacing between adjacent contours depends on the shape of the letters:
  • Straight-straight: II, IN, IM, IP etc.
  • Straight-curve (or curve-straight): IO, QR etc.
  • Straight-slant (or slant-straight): IV, IW etc.
  • Curve-curve: OO, OG etc.
  • Slant-curve (or curve-slant): VO, WG, VC etc.
  • Slant-slant: VW, VX etc.
• Leave the space between words equal to the space required for writing a letter "O".

Line Types : Basic Line Types & Name according to application

• Visible line: Continuous line, thick. Represents features that can be seen in the current view.
• Hidden line: Dash line, thin. Represents features that cannot be seen in the current view.
• Dimension line: Continuous line, thin. Indicates the sizes and locations of features.
• Extension line: Continuous line, thin. Extends from the object to the dimension line.
• Leader line: Continuous line, thin. Connects a dimension or note to a specific feature.
• Center line: Chain line, thin. Represents symmetry, path of motion, centers of circles, and axis of axisymmetrical parts.

Elements of a Drawing

• Engineering drawings require both graphics and word languages.
• Graphics describe the object's shape primarily.
• Word language describes the exact size, location, and specification of the object.
• Text on drawings includes dimensions, notes, and the title block.

Knowledge and Skills Require : Engineering Drawing

• Graphics language:
  • Geometric construction
  • Projection method
  • Using line types
• Word language:
  • Dimensions & Notes
  • Visualization

Drawing Sheet : Standard size (JIS)

• Standard sheet sizes are A0, A1, A2, A3, and A4.
• Dimensions are in millimeters:
  • A4: 210 x 297
  • A3: 297 x 420
  • A2: 420 x 594
  • A1: 594 x 841
  • A0: 841 x 1189

Drawing Sheet : Orientation & Margin

• Orientation refers to the layout of the drawing on the sheet.
• Margin refers to the blank space around the drawing area.
• The sheet should be oriented with the longer side as the vertical direction.
• Margins are used for binding, folding, and leaving space for notes and other information.

Definition and Necessity

• Drawing standards are a set of rules that govern how technical drawings are represented.
• They ensure drawings convey the same meaning to everyone who reads them.

Standard Code

• Different countries have different standard codes:
  • USA: ANSI (American National Standard Institute)
  • Japan: JIS (Japanese Industrial Standard)
  • UK: BS (British Standard)
  • Australia: AS (Australian Standard)
  • Germany: DIN (Deutsches Institut für Normung)
  • International: ISO (International Standards Organization)

Pictorial Projection

• Pictorial projections are used to represent three-dimensional objects on a two-dimensional plane.
• Two main types: Axonometric and Oblique projections.
• Axonometric projection: parallel lines of sight are normal to the picture plane.
• Oblique projection: parallel lines of sight are oblique (not normal) to the picture plane.

Axonometric Projection

• All parallel lines in space remain parallel in the projection.
• The projection is determined by the angle between the line of sight and the picture plane.

Types of Axonometric Projection

• Isometric: All three angles are equal.
• Dimetric: Two of the three angles are equal.
• Trimetric: All three angles are unequal.

Oblique Projection

• Oblique drawing angle is the angle between the line of sight and the picture plane.
• Two main types: Cavalier and Cabinet.
• Cavalier: full scale in all directions.
• Cabinet: full scale in one direction, half scale in the other.

Isometric Projection

• Regular isometric: View point is looking down on the top of the object.
• Reverse isometric: View point is looking up on the bottom of the object.
• Long axis isometric: View point is looking from the right (or left) of the object.
• Isometric lines are parallel to any of the isometric axes.
• Nonisometric lines are not parallel to any of the isometric axes.
• In an isometric drawing, a circle appears as an ellipse.
• Isometric drawings are used for a variety of purposes, including technical drawings, architectural plans, and product design.

Isometric Sketching

• Sketch from an actual object: Place the object in a position where its shape and features are visible. Define an isometric axis. Sketch the enclosing box (or cylinder). Estimate the size and relationship of each detail. Darken all visible lines.
• Sketch from a multiview drawing: Interpret the meaning of lines/areas in the multiview drawing. Locate the lines or surfaces relative to the isometric axis.
• Hidden lines in isometric sketches/drawings are omitted unless absolutely necessary.

Oblique Sketching

• Complex features are placed parallel to the frontal plane.
• The longest dimension of an object should be parallel to the frontal plane.

Orientation of Isometric Axes

• Isometric axes can be arbitrarily oriented to create different views of a single object.

Distance in Isometric Sketch

• True-length distances are shown along isometric lines.

Isometric Projection vs. Isometric Drawing

• Isometric projection (true projection): the projection is a true representation of the object, but it is not full scale.
• Isometric drawing (full size): it is a full-scale representation of the object, but it is not a true projection.
• Isometric drawing is a full-size, full-scale representation of an object, but it is not a true projection.
• Isometric projection is a scaled representation of an object.