Dimension, Extension, and Leader lines

Dimension, extension, and leader lines play crucial roles in providing essential measurements, indicating features, and directing attention to specific areas of interest. Understanding these lines is vital in the interpretation and creation of technical drawings.

Dimension Lines

Dimension lines are used to indicate the size and location of features in an engineering drawing. They provide measurements that define the length, width, height, or diameter of objects, allowing for accurate replication and manufacturing. Dimension lines are drawn as continuous, thin lines with arrowheads at each end. If there is space available, the arrows should be placed within the dimension. The numerical value representing the measurement is placed in line with the dimension line.

Extension Lines

Extension lines are used to indicate the boundaries of a feature to which a dimension is applied. They extend from the edges of the object or feature being measured and intersect with the dimension lines. Extension lines help define the specific area or section to which the dimension applies, ensuring clarity and eliminating ambiguity. These lines are drawn as thin, unbroken lines and should not touch the object being dimensioned. By providing clear references, extension lines contribute to accurate and standardized measurements in engineering drawings.

Leader Lines

Leader lines are used to direct attention to specific areas or features on an engineering drawing. They are typically utilized when pointing to notes, labels, or callouts that provide additional information about a particular object or detail. Leader lines are drawn as straight lines (but not horizontal or vertical) that originate from a specific location and end with an arrowhead or a dot. A short horizontal portion should extend to the first or last letter of the note. The arrowhead or dot indicates the precise location being referenced. Leader lines help draw attention to critical details, annotations, or dimensions, enhancing the overall clarity and comprehensibility of the drawing.