What is a Plumb Bob?
A plumb bob is a weighted object connected to a string that can be used to establish a vertical line. That weighted object can be as simple as a rock or as elaborate as the brass plumb bob shown. Some are bullet- or cone-shaped, but in the DIY world they’re often in the guise of a chalk box or chalk line.
Plumb bobs have been around a long time. Egyptians used them to build the pyramids and builders throughout the ages have used them to determine if walls are “plumb” or perfectly vertical. They’re ideal for tasks like centering lights over a kitchen island, determining the proper spacing of recessed lights or framing basement walls.