DIMENSIONING:BASIC RULES

• Use enough dimensions to show the size of all object features.

• Do not repeat dimensions if you already have them or they can be worked out from others you have on the drawing.

• Place dimensions in the clearest possible way.• All dimensions will be written using the same unit.

Stand-alone numerical values mean millimeters.• Dimensions should be read from the bottom

(horizontal lines) or right hand side (vertical lines)• Dimension values must be placed above and parallel

to dimension line.

Dimensioning: General rules

2 mm.

7 mm.

59

Dimension line Arrows ValueExtension lines

Dimensioning: Items

Dimension line must be kept apart at least 7 mm from the drawing.

Extension lines must exceed dimension line about 2 mm.

Dimensioning: Edges

Dimension lines can not match any edge...

...nor prolong any edge...

...nor match any axis

Dimension lines do not cross each other, nor cross any other line or item of the drawing.

Dimensioning: Edges

Dimension lines must be placed at the same level

Chain Dimensioning

Parallel Dimensioning

Dimension lines do not cross each other, nor cross any other line or item of the drawing…

Thus, using parallel dimensioning: The smaller is a dimension value, the closer we place it in the drawing

45 156 5035

If line is too small, place arrows outside the extension linesIf room is too small, place value outside, on the right

If arrows can not be placed outside, place a point instead......and write value using an auxiliary line, same oriented.

Dimensioning: Small edges

35

Dimensioning: Diameters

3030

•Dimension lines must not match any symmetry axis.

•Use diameter values for arches higher than 180º

•Two dimension lines sharing same center must be placed using different slopes.

Dimensioning: Diameters

45

65

25O

•In case you have concentric circumferences, do not place more than 2 dimension lines in the same part of the drawing.

•Add the diameter symbol “Ø” before the numeric value to clarify an unclear diameter.

•Dimension line must not match any symmetry axis.

•Use diameter values for arches higher than 180º

•Two dimension lines sharing same center must be placed using different slopes.

Dimensioning: Radius

•Use radius values for arches equal to or lower than 180º.

20

60

•If room is too small, place arrow and value outside

R 9

0

•If center is located beyond the scope of the drawing, add the radius symbol “R” before the numeric value…

… and this unfinished dimension line must follow the same radius direction.