Alphabet of Lines

• What is a line defined as mathematically?

  An imaginary path of moving points
• Why are lines important in drafting?

  Lines structure and articulate drawings
• What are the conventional symbols for lines called?

  The alphabet of lines
• Why do we study lines in drafting?

  Each type of line has a precise symbolic meaning
• How does line thickness affect a drawing?

  It expresses contrast and importance
• What is the purpose of line symbols in engineering and design?

  To express features of designed products clearly and accurately
• What are the key characteristics of object lines?

  • Thick full line
  • Represents all visible edges of objects
  • Also known as visible lines
• What defines hidden lines in drafting?

  • Medium short dashed lines
  • Used to represent hidden or unseen edges of objects
• What is the center line?

  • Thin line with long and short dashes
  • Indicates axis or centers of holes or symmetrical objects
• What is a dimension line?

  • Thin, fine, dark solid line
  • Terminated by arrowheads at both ends
  • Shows the size of the part of the drawing
• What is the purpose of an extension line?

  • Thin, dark solid line
  • Extends from a point on the drawing to a point of measurement
  • Shows the starting and ending of dimension
• What is a cutting plane line?

  • Extra thick line
  • Shows cutaway views or plane of projection
  • Indicates direction of view
• What is a leader line used for in drafting?

  • Thin straight line
  • Comes from a dimension value or explanatory note
  • Points to an area of a drawing requiring a note for explanation
• What is the purpose of a short break line?

  • Visible irregular curve drawn in freehand
  • Shows that an area or part of an object is shortened
• What does a long break line represent?

  • Thin line drawn in succession with breaks
  • Shows that the object has been cut
  • Used if the drawing is too long for the drawing paper
• What are section lines used for?

  • Show the cut surface of the section views
• What is a phantom line used to indicate?

  • Long line followed by two short dashes
  • Shows alternate position of a moving part
• What is the purpose of a construction line?

  • Very light and thin line
  • Used to construct layout work