1. Dimensioning Working document
Ø 8
FACING Ø14 X 3 DEEP 80 50 45
40° 13 20 40
Technical drawings must not only faithfully reproduce the shape of objects, but also serve as a guide to their construction or manufacturing.
Dimensioning an object means giving all the necessary dimensions to build a technical object.
Working document
Linguistic review

2. Dimensioning
Ø 8
FACING Ø14 X 3 DEEP 80 50 45
40° 13 20 40

3. Dimensioning
Lines
To enter dimensions and specify their place we use a fine line, called a dimension line, ending in arrows.
The dimension is placed in the center of the dimension line.
Its value is given in millimetres.
Units are not shown. 36
The extension line is a fine line that connects the measured part of the object to the dimension line.

4. Dimensioning Drawing the dimensions
approx.
10 mm
The distance between the object and the dimension line or between two dimension lines is about 10 mm.
The dimension line touches the extension line.
approx.
2 mm
approx.
1 mm
The extension line extends past the dimension line.
The extension line does not touch the object.

5. Dimensioning Dimensioning includes two stages:
The first defines the overall shapes of the object using general dimensions.
Dimensions shown include the object’s length, width and height.

6. Dimensioning
The second stage is used to specify the placement of different parts of the object by adding in position dimensions.

7. Dimensioning Basic rules for dimensioning
Line up the position of dimensions.
Do not indicate dimensions for hidden feature lines.
If necessary, indicate outside the extension lines.

8. Dimensioning Dimensioning cylindrical shapes
Objects with rectangular shapes are dimensioned differently than those with cylindrical shapes.
The shapes of rectangular objects are dimensioned in relation to surfaces.
Round or cylindrical shapes are located in relation to their center.

9. Dimensioning Basic rules for dimensioning
If possible, group all dimensions between or above views.
Place the dimension where the shape best describes the object.

10. Dimensioning Basic rules for dimensioning
Place the shortest dimension lines close to the object to be measured
In a series of dimensions, one of the ends of the series is not indicated.

11. Dimensioning Dimensioning cylindrical shapes
Objects with rectangular shapes are dimensioned differently than those with cylindrical shapes.
The shapes of rectangular objects are dimensioned in relation to surfaces.
Round or cylindrical shapes are dimensioned in relation to their center.

12. Dimensioning Dimensioning cylindrical shapes
The leader line may be drawn at 30º, 45º or 60º.
The line touches the circle and points to the center.
Ø 25
DIA 25
The Ø symbol or abbreviation DIA precedes the diameter to be dimensioned.
Ø 20
R18
Cylindrical holes are dimensioned by a note specifying the diameter and depth, if necessary.
Curves composed of arcs of a circle are dimensioned by their radius.

13. Dimensioning Summary Ø 8 Leader line FACING Ø14 X 3 DEEP80 50 45
Ø 8
FACING Ø14 X 3 DEEP
40° 13 20 40
Shape dimension
Position dimension
Dimension
Extension line
Dimension line

14. Dimensioning example for an object that includes cylindrical shapes
Ø5 - 2 HOLES R5

15. Dimensioning Bibliography Working document
GIESECKE, Frederick E., MITCHELL, Alva, SPENCER, Henry Cecil, HILL, Ivan Leroy, GYGDON, John Thomas et NGUYEN, Dinh N. « Dessin technique », Montréal, Éditions du Renouveau Pédagogique inc., 1982, 769 p.
JENSEN, C.H. « Dessin industriel », Montréal, McGraw-Hill, 1972, 752 p.
STIRLING, Norman. « Éléments de dessin industriel », Montréal, HRW, 1979, 372 p.
Working document