Dimensioning Rules: ISO 129-1:2004 == UNE 1039:1994

  • Elements of dimensioning should be drawn with finer(thinner) lines than the edges of the object (thicker)
  • It is not necessary to dimension all the edges of an object (the minimum number of dimensions required to understand the drawing).
    Elements of dimensioning:
    • Dimension:
    • It is the number that show the real measurement of the object.
    • Normally in millimetres.
    • Must be in the centre (middle) of, and parallel to the dimension line.
    • Must be above horizontal dimension lines and left of vertical dimension lines.
    • If there is not space on the dimension line to put the dimensions, they can be placed on a leader line.
    • Dimension lines:
    • Must be parallel to and the same length as the edge (side) of the object.
    • Must be placed outside of the object.
    • If there is a smaller object inside the main one you can put dimension lines inside the object.
    • We cannot use the edges of the object as dimension lines.
    • Dimension lines should not cross other lines.
    • Dimension lines should be situated at least 8 mm away from the edge of the object.
    • The following dimension lines should be situated at least 5 mm away from other.
    • Symbols at the end of the dimension lines:
    • They are usually arrowheads or oblique stroke (slashes) or if there is not space to put arrowhead dots.
    • If the arrows or dimensions do not fit on the dimensiones line, they should go outside the line.
    • Extension lines;
    • It is a line perpendicular to the dimension line.
    • Extend for 2mm on each side of the dimension lines.
    • Leader lines;
    • This shows a note, a number, data related to the object.
    • Symbols;
    • Before the dimension number.
    • Radius: R Diameter: ∅ Square: □ Sphere: radio SR diameter S∅
  • Angles are dimensioned with arcs.
  • Radii and diameters can be dimensioned inside a circle or indicated by an arrow at the point of contact with the circumference.