Which tool is best suited for vertical plumbing to locate points?

The plumb bob is specifically designed for establishing a true vertical line, making it the best choice for plumbing tasks where precision in vertical alignment is crucial. A plumb bob consists of a weight attached to a string. When suspended, the weight pulls the string down to align perfectly with the force of gravity, indicating a vertical point. This is especially useful in construction and plumbing to ensure that pipes, walls, or fixtures are perfectly upright, aligning them accurately in relation to one another.

On the other hand, tools like the portable circular saw, portable electric drill, and portable jigsaw are primarily designed for cutting materials and do not serve the purpose of determining vertical alignment. They may assist in various woodworking and construction tasks, but none of them are intended to locate points in a vertical manner like the plumb bob can. Thus, for tasks requiring precise vertical measurement and alignment, the plumb bob is the most appropriate tool.