Sign In to join the community | Help
Tools & Hardware

What In The World Is a Plumb Bob?

plumb bob is a precisely machined weight, usually with a pointed tip on the bottom, suspended from a string and used to create a vertical reference line, or plumb line. In construction, all walls or columns must be plumb or true vertical to the world.

Brass Plumb Bob

Plumb bobs were used by artisans in ancient Egypt to create some of the greatest structures in the world. Surveyors use plumb bobs to pinpoint a precise spot on the ground to use as a reference point for determining land elevations and marking property lines.

These precise marks known as datum marks are used to pinpoint datum lines for building measurements. Builders would place a plumb line on the scaffolding with the plumb bob centered over the datum mark as the construction proceeded the scaffolding was raised higher and the datum line raised to assure accuracy of the wall. Many cathedral domes and towers still have brass datum marks inlaid into their floors, which signify the center of the structure above. The early skyscrapers used heavy plumb-bobs, hung on wire in their elevator shafts too assure the accuracy of their construction.

I recently used a plumb bob to mark the center of my cook top on the ceiling, as I installed my new island range hood. This allowed me to precisely center the hood over my cook top.

The next time you need to assure the accuracy of any vertical surface, use plumb bob, a very simple device that uses gravity to make precise measurements.


Mike, The Home Depot Answer Man

Not what you were looking for ? Try posting a question
Posted 2019-01-22T02:11:01+0000  by Mike_HD_OC Mike_HD_OC