Plumb to measure, which one to buy and how to use it?

November 2, 2021

The plumb bob is usually a weight made of lead, although it can be made of any other metal of similar density. It is shaped like a cylinder or prism , while its lower part is shaped like a cone. The upper part usually has a hole from which a string or string emerges from where the plumb bob hangs vertically.

This plumb line can also be called a nautical probe, since it determines the depth in a body of water; while in architecture (the other area where it is used) it has the role of designating the verticality of a surface.

Main uses of the plumb bob for measuring

Using gravity as the main ally, the plumb line can be in charge of determining what things are really vertical in a construction, being used mostly with walls, walls and other types of surfaces that require this type of verification.

When determining how vertical a wall or wall is, it is checked how stable it is and if it distributes the weight in the correct way in the structure, also ensuring that said construction can be precisely the same as the plan and / or scale model made on it. expected result.

The use of the plumb line is very important, marking a difference between the collapse of a structure and its full resistance . If the check is not carried out with the plumb line, there is a risk that the wall, wall or any surface ends up giving way due to not having a correct distribution of the weight or the necessary resistance.

On the other hand, when used in its role as a marine probe, the plumb line uses its weight (usually considerable) to reach the bottom of the body of water, while holding its line on the surface. When the plumb bob hits the bottom, a slight vibration can be felt in the string, signaling that the bottom point can be marked for accurate measurement.

In this area, the plumb line eliminates inaccuracy and inefficiency, since its weight allows gravity to push it to the bottom without being pushed or pulled by the current.

Parts of the plumb bob for measuring

The plumb bob has three specific and invariable parts, which are:


It weighs exactly 500 grams , being made mostly of lead, bronze or steel, to ensure that it is compact but heavy . It is shaped like a cylinder or prism in many cases and its lower part more closely resembles a cone or pyramid (which is ideal when used as a marine probe).

Tent, thread or rope

This is the string that holds the weight . It is responsible for the weight to hang, holding it in a hole or slot in the upper part of the plumb line. Its length can vary, being even in the case of the nautical probe, long enough to give a measurement of several meters.


It is located in the upper part of the weight, having the same diameter as this, although it is made of magnetic metal or wood. In this part the hole or slot that connects the string to the rest of the plumb line is located.

Calibrate the plumb to measure

Before being used, the plumb bob must be calibrated to ensure accuracy and precision in the results obtained. The first thing to do for calibration is to check that the groove or hole of the finger is the same size as it; This check ensures that small errors and variations in results are avoided.

A supplement of between 1 and 2 millimeters must be glued on one side of the walnut, with that a slight separation of the weight is achieved to take a measurement. If the pendulum were to stick, the result would be wrong, the same thing happening if it moves further than necessary.

It must be checked that both the nut and the weight share the same diameter ; As long as both are perfectly aligned, the results obtained will be accurate; When this is not the case and they are misaligned, by sheer inertia the plumb bob begins to rotate on its grip, causing its fibers to separate.

You can check the calibration of the plumb bob before using it, solving any unforeseen and inconvenient that may arise before doing so.

How to use the plumb bob?

Although the process of using the plumb line may seem simple and does not require a lot of effort, the following steps are necessary to ensure a good result.

  1. Stretch the handle and release it from the nut.
  2. Support the nut on the surface to be plumbed (wall, wall, etc).
  3. Slide the touch until the plumb bob is at the lowest point of the surface, allowing it to swing freely (consider that the supplement that separates the weight and the nut will determine the precision; more separation is greater accuracy in the result than will be obtained).
  4. When the weight stops swinging , its position is compared to obtain a plumb result.
  5. The result is correct when the plumb line is resting on the object without touching it directly (with a more or less one millimeter of separation), meaning that the surface is completely vertical.
  6. If the plumb bob is further away from the surface, its position must be corrected, bringing it closer to the weight, the opposite being the case when the plumb bob rests completely on it.

Types of plumb to measure

The variety of plumb bobs is defined according to their weight, although they do not have explicit categories.

In the first place, the plumb bobs are defined according to the field in which they are used and their materials, the smallest being between 30 and 40 grams , while the largest are between 400 and 600 grams.

The smallest type is usually used in medicine (physiotherapy and osteopathy), while the larger ones are used in construction and navigation . It should be noted that all plumb bob models are very accessible, regardless of their characteristics.

Plumb bobs for measuring are quite an important element in architecture and construction, which is why knowing how to handle them in the correct way, as well as the type that is most recommended for these areas, makes a difference in any job and its performance.

Dr. Loony Davis5
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Born and raised in Brussels in an English family, I have always lived in a multicultural environment. After several work experiences in marketing and communication, I came to Smart Water Magazine, which I describe as the most exciting challenge of my career.
I am a person with great restlessness and curiosity to learn, discover what I do not know, as well as reinvent myself daily, someone who is curious about life and wants to know. I enjoy sharing knowledge.
This is my personal project but I also collaborate in other blogs, it is the case, the most important web on water currently exists in the US, if you are interested you can read my articles here.

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