A hidden line, also known as a hidden object line is a medium weight line, made of short dashes about 1/8” long with 1/16”gaps, to show edges, surfaces and corners which cannot be seen. Sometimes they are used to make a drawing easier to understand.

What is the difference between a construction line and a hidden line?

Construction Line: Very lightly drawn lines used as guides to help draw all other lines and shapes properly. Hidden Line: Lines used to show interior detail that is not visible from the current outside view of the part.

A drafter—in deciding whether a line in a view should be represented as hidden or as visible—relies on the fact that in third-angle projection the near side of the object is near the adjacent view, but in first-angle projection the near side of the object is remote from the adjacent view.

What is the purpose of hidden lines and centerlines?

Hidden lines show edges of details that are not visible from the point of view shown in the drawing. Center lines define the center of arcs, circles, or symmetrical parts.

also called visible lines, are used to show the main outline of the building, including exterior walls, interior partitions, porches, patios, driveways, and walls. These lines should stand out on a drawing. Thin unbroken lines that show the width or size of objects.