PRACTICAL HINTS ON DIMENSIONING

 1) Dimension lines should be drawn at least 8 mm away from the outlines and from each other.

2) Dimensions in a series may be placed in any one of the following two ways:

a) Continuous or Chain dimensioning:

Dimensions are arranged in straight line. An overall dimension is placed outside the small dimension. Least important dimensions is generally omitted.

b) Progressive or parallel dimensioning:

All dimensions are calculated from a common base line. Cumulative error is avoided by this method. This method is preferable compared to other.

3) Smaller dimensions should be placed nearer the view and the larger further away that so that further away so that extension lines do not cross dimension lines. Extension lines may cross each other or the outlines.

4) When a number of parallel dimension lines are to be shown near each other, the dimensions should be stagged.

5) Dimension should be placed where the shape is easily identified.

PLACING OF DIMENSIONS

          It is necessary to indicate the size, and other details of the object for the construction and function, using lines, numerals, symbols, notes etc, we indicate the details in a drawing by proper dimensioning. Dimensions are written either above the dimension lines or inserted at the middle by breaking the dimension lines.

Normally dimensions are placed according to either of the following two systems:

1) Aligned System and

2) Unidirectional system

1) Aligned system:

          In Aligned system, the dimension is placed perpendicular to the dimension line in such a way that it may be read from the bottom edge or the right-hand edge of the drawing sheet. The dimension should be placed near the middle and above, clear of the dimension lines.

2) Unidirectional system:

          In unidirectional system, all the dimensions are placed in one direction such that they can be read from the bottom of the drawing. In this system, the dimension lines are broken near the middle for inserting the dimensions. This system is mainly used on large drawings -- as of automobiles etc., where it is inconvenient to read dimensions from the right-hand side.