What type of lines connect the ends of a dimension line to a part feature?

Extension lines connect the ends of a dimension line to a specific part feature. These lines are used in technical drawings to clarify the limits of the dimension they represent. They help ensure that the measurement is accurately associated with the specific feature, such as an edge or hole, that is being dimensioned.

Extension lines are typically drawn as thin, solid lines and are positioned at a slight distance from the part feature to avoid confusion. Their primary purpose is to guide the viewer’s attention from the dimension to the relevant feature in the drawing, promoting clarity and understanding in the communication of measurements.

In contrast, leader lines are used to indicate a specific note or dimension that points to a feature, center lines denote symmetry and axis of rotation, and construction lines are used primarily as guides for layout purposes during the drafting process. These differences highlight the unique role extension lines play in the context of dimensioning in technical drawings.