What is the primary tool used for cutting straight lines in lumber?

The primary tool used for cutting straight lines in lumber is a circular saw. This tool is designed specifically for making long, straight cuts across a variety of materials, including wood, and is effective for swiftly cutting through large sheets of lumber or thick boards. The blade of a circular saw rotates at high speeds, allowing it to maintain a straight cut along a marked line, which is essential for precise carpentry work.

While other tools, such as a jigsaw and hand saw, can also cut through lumber, they are generally more suited for curved cuts or softer materials, rather than the clean, straight lines that a circular saw is optimized for. A miter saw excels at making angled cuts and crosscuts, but it does not serve the purpose of long, straight cuts in the same way a circular saw does. Therefore, the circular saw stands out as the ideal choice for tasks requiring efficient and accurate straight cuts in lumber.