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4.5 Execution of Dimensions

Projection and dimension lines as a thin continuous line. Projection lines should extend
slightly beyond the respective dimension line. Projection lines should be drawn

perpendicular to the feature being dimensioned. If the space for dimensioning is

insufficient, the arrow heads may be reversed and the adjacent arrow heads may be
replaced by a dot. However, they may be drawn obliquely, but parallel to each other in

special cases such on tapered feature.

Figure 4.9 : Dimensioning in narrow space and a tapered feature

4.5.1 Extension and dimension line

Projection or extension and dimension line should be drawn according to the

standards of practices in engineering drawing. The standard practices are :

• Always leave a visible gap (≈ 1 mm) from a view centre lines before start

drawing a line.
• Extend the lines beyond the (last) dimension line 2-3 mm.

Figure 4.10 : Extension line