working drawings - part 2

• What are dimension and projection lines compared to drawing lines?

  They are thinner than the drawing lines.
• How should dimension lines connect to projection lines?

  With a small filled-in arrowhead at each end.
• Where should the shortest dimensions be placed in a drawing?

  Closest to the drawing.
• In what unit are measurements usually written in dimension lines?

  Millimeters (mm).
• How should measurements be positioned on dimension lines?

  In the middle, readable from bottom or right.
• What prefix is used for the radius in dimensioning?

  R.
• What symbol is used for diameter in dimensioning?

  Ø.
• What does the arrowhead in dimensioning indicate?

  It points towards or away from the centre.
• What is the purpose of symbols in mechanical features?

  To advise manufacturers on required features.
• What does the abbreviation CL stand for?

  Centre line.
• What does the abbreviation DIA represent?

  Diameter in a note.
• What does the abbreviation Ø indicate?

  Diameter preceding a dimension.
• What does the abbreviation AF stand for?

  Across flats.
• What is the purpose of the surface finish symbol?

  To advise on the machined finish required.
• What is the surface finish symbol for 'material removal not allowed'?

  Specific symbol not provided in material.
• Where is machining information located in relation to the surface finish symbol?

  Around the symbol.
• What type of line represents hidden detail in orthographic drawing?

  Hidden line.
• What are the different types of mechanical features symbols used in drawings?

  • Chamfer
  • External thread
  • Internal thread
  • Straight knurling
  • Diamond knurling
  • Through hole
  • Blind hole
  • Countersink
• What are the standard abbreviations used in drawings according to British Standard BS 8888?

  • AF: Across flats
  • CL: Centre line
  • DIA: Diameter in a note
  • Ø: Diameter preceding a dimension
  • DRG: Drawing
  • MAT: Material
  • SQ: Square in a note
• What are the types of lines used in orthographic drawing?

  • Dimension lines
  • Projection lines
  • Hidden lines
  • Leader lines