What is the main purpose of extension lines in technical drawings?

Extension lines are used in technical drawings primarily to indicate the starting and ending points of a dimension. They extend from the object outlines to the dimension line, helping to clarify the specific areas of measurement without cluttering the drawing itself. This makes it easier for anyone interpreting the drawing to understand precisely where the measurements are being taken.

The use of extension lines is essential for accurate communication in construction and manufacturing processes, as they help to eliminate ambiguity regarding what is being measured. By clearly marking dimension points, extension lines ensure that the correct dimensions are communicated and can be accurately reproduced in physical form. This function is crucial for achieving proper assembly and construction based on the provided specifications.