What type of lines are used to indicate cutting or viewing planes in a drawing?

• A. Thin dashed lines
• B. Heavy solid lines
• C. Freehand zigzag lines
• D. Medium phantom lines

Answer: (B)

The indication of cutting or viewing planes in a drawing is typically represented by heavy solid lines. These lines stand out prominently in a technical drawing, making it clear where the section view or cut is taking place. The use of heavy solid lines helps to convey critical information about the geometry of the element being represented, allowing engineers and mechanics to understand the internal features and dimensions once the object is cut along that plane. This visual distinction is essential for interpreting how parts fit together and function in the assembly.

Options suggesting thin dashed lines or medium phantom lines do not adequately convey the necessary clarity for cutting or viewing planes, as dashed or phantom lines serve different purposes in technical drafting. Freehand zigzag lines are often used to represent irregular surfaces or to depict specific types of contours, rather than to indicate cutting planes, which require a clear definition that heavy solid lines provide. The emphasis on heavy solid lines is aligned with standard drafting practices, ensuring consistency and effectiveness in communication among engineers and mechanics.