How Does a Plumb Bob Work?
What Is a Plumb Bob? A plumb bob is a humble tool consisting of a weight at the end of a string. “Plumb” comes from the Latin term “plumbum” for the element lead, indicating a lead slug tied to a string. One end of the string is affixed at a point above the floor or ground, and the weight is allowed to hang free until it stops moving. This shows the user “true vertical.” With a plumb bob, anyone can measure or draw a line parallel to Earth’s gravity. Plumb bobs often have carefully machined brass or bronze weights with points on the end and cotton or water-resistant nylon string. The point represents the spot directly below the origin of the string. Aside from modern plumb bobs using newer manufactured materials, the plumb bob has not changed in millennia. Use in Construction From surveying to masonry to interior design, plumb bobs are a useful tool for all phases of construction, even in the age of electronic and laser-guided tools. Lasers send a true straight line but do so in any di
