Imagine, you have to build a wall which is very tall, you can lay brick upon brick to build higher and higher but eventually, you will realize that your wall has leaned at least a little to one side of your structure; it is imperfect.
The human eye cannot be precise enough to build structures which will be perfectly vertical to the ground. It is even more difficult where the ground itself is not level and, unfortunately, most of the exposed ground in the world is not level. If your structure fails to balance itself properly, it will lean and eventually fall.
But the tall buildings of this world are all perfectly balanced and they don’t fall, rather, their mighty height has given them the stature of Sky-Scrapers! Their construction was possible because of one simple tool; Plumb-Bob.
So, we are going to discuss why you too need one and how you can get the best plumb-bob from the market.
- What is a Plumb-bob?
- How Does a Plumb-Bob Work?
- Best Plumb Bob Reviews
- What Does It Mean by Something to Be Plumbed?
- How to Buy the Best Plumb-Bob?
- How to Use a Plumb-Bob Step by Step Guide
- Final verdict
What is a Plumb-bob?
According to Wikipedia, ‘A plumb-bob, or plummet, is a weight, usually with a pointed tip on the bottom, suspended from a string and used as a vertical reference line, or plumb-line’. 
This is a tool used all over the world by mechanics, building workers, civil engineers, and many other professionals. It is basically a simple weight hung from a wire. The basic principle is that gravity pulls any object vertically towards earth. A bob hanging from a thread will eventually create a perfectly vertical line from any height.
This instrument has been in use almost from the beginning of our civilization. Even, the ancient people from Mesopotamia used to use it. The plumb-bob has changed very little from its early days; it has only become more precise.
How Does a Plumb-Bob Work?
A plumb-bob gets its name from Plumbum which is the Latin name for lead because, in the past, plumb-bobs used to be made from lead. It was heavier than other metals and cheaper too. The basic working principle is simple. The bob hangs on a thread from any reference object and the line it creates, marks the exact line which will be vertical to Earth.
The tip of this instrument is pointy and the workmen can mark a point on the ground which will work as a reference point for the zenith of the point it was hung from.
Modern plumb-bob sometimes uses electronics and scales to accurately measure the slope of any surface.
Best Plumb Bob Reviews
To make life a bit easier for you, we have added some reviews of some products
1. Tajima PZB-400G Plumb-Rite
The plumb-bob is made by the Japanese and the quality lives up to their mark. The tool has a steel bob hanging from a wire just like a traditional plumb-bob but there are some very useful features.
The thread is reeled in a pack and it has a simple mechanism that allows you to pull down the string for higher measurements and simply pull up for retracting the string. You don’t have to reel it in. There are different settings on the tool for different weights.
The top part of the tool has a sharp pin which can be driven into wood. The pin is very pointy so it does not do much damage to the surface. The company asks the users not to pull the pin out but to twist it before to loosen it up a little.
The side that touches the wall also has a magnet attached to it. This allows you to stick it up on a metal surface and it will hang from there. This makes it even more convenient.
There is a very clever feature; there is a hook at the bottom of the magnet. When the string hangs from the tool, it hangs two inches away from the wall. Sometimes you will need it to be hanging just over the edge. This hook can be used for it; you just have to hook the thread into it.
The bob has a sharp edge and to protect its accuracy the tool comes with a cap on it.
Altogether, this is a very useful tool and it is used worldwide by professionals.
2. Stanley 47-974 16 oz Brass Plumb-bob
This tool is a pretty useful tool for everyday use. The plumb-bob is simple and does not have many features.
The tool does not come with a string. You will have to manage it yourself. The bob is made of brass and it is heavy; 1.15 pounds to be precise. It has a pointy tip and it is made of hardened steel. This bit of the machinery is replaceable.
Sometimes, you may accidentally drop it on metal or slab and break the tip. In that case, it must be replaced.
The tool does not have many features but has a limited lifetime warranty.
3. General Tools 790-8 Hexagon Steel Plumb-bob
This one is also a very simple tool. The bob is made of steel and it looks like a fat pencil. The tool is small and lightweight. This allows better mobility.
The tool comes with a 10-foot long cord which is braded. This ensures that the plumb-bob will not spin while operating.
This is very useful for indoor work but for outdoors, the wind will mess with its accuracy.
The tool is very cheap comparing to the others;
4. AWF-Pro Plumb-bob Kit
This plumb-bob tool comes with a package which actually has another bob in it. The small nylon bag contains two carpenter’s pencils and a sharpener. There is a retractable reel in it for the thread.
The kit is useful for two reasons. The first one is that it has two bobs of different weight. This is handy when you are working in various spots. The bigger bob allows better precision. On the other hand, the smaller one is for the tight spaces.
It is useful but the price is a bit more than expected. Though, you have to keep in mind that the bobs which are made of brass, do cost more than those which are made of steel.
5. IRWIN Tools Hexagonal Plumb-bob
This is plumb-bob for everyday use. Though the steel made bob will not ensure precision, it is precise enough for household garage works. The professionals might choose other products over it because there are very little that it offers. The beginners might choose it because it is cheap and it gets the job done.
The metal body is corrosion resistant so you won’t have any problem while working on a rainy day.
What Does It Mean by Something to Be Plumbed?
When somebody says that something is plumbed what they actually mean is that the object in question is placed on the ground in a way that the center of gravity of that object is resting in between the support legs or edges. And, the weight is equally distributed among the support legs or edges.
This sounds a bit too technical but if we put it in simple terms, something is plumbed when it is either properly vertical or for compound structures, it is balanced or leveled. So, we can say that a wall is plumbed when it is at 90° angle from the horizontal line. And, for a compound structure, a dome perhaps, it is plumbed when the peak of that dome is just above the center of the bottom circle.
The point is, when something is plumbed, it will not tip over.
How to Buy the Best Plumb-Bob?
Before rummaging through the market, you need to know what to look for in your plumb-bob tool.
To ensure that you are buying the best plumb-bob for yourself, some points are to be considered.
The first thing you should keep in mind is why you need a plumb-bob. If you are a civil engineer and your neighbor is a building worker then the two of you will need two different kinds of plumb-bobs.
Being a civil engineer, you will need more precision while you can ignore the size or price of the tool. Your neighbor, on the other hand, will need to consider the size and weight of the tool because he will have to carry this around.
Material of the Bob
The material for a plumb-bob is usually metal. The heavier ones are made of brass and the lighter ones are made of steel.
Usually, the heavier ones are good for outdoors where the breeze can sway the lighter ones very easily. For indoors, the lighter ones take less time to settle and they can be easily carried in a tool-box.
The thread used for a plumb-bob is important because if it is too stretchy the accuracy of the tool will be hampered. If it absorbs too much moisture from the atmosphere it will stretch. If the thread is made of twisted ropes then it will spin. If the line is too stiff, the vertical line will be bent a little.
Usually, if you are buying a cheap version, your thread will be troublesome.
The tool is simple and there are little reasons for buying a costlier one when you can get your work done with something much cheaper.
How to Use a Plumb-Bob Step by Step Guide
Using a plumb-bob looks very easy but actually, it takes some experience to do it properly.
You just let your bob hang from a piece of wire and it the wire will work as a reference for a perfectly vertical line.
Carpenters use it to fit doors, windows or stair-railings. You have to hang the bob from a piece of the nail if you want to use it this way. Then measure the distance of the knot on the nail from the wood surface and again at the bottom. This time do not measure from the actual bob, measure it from the wire. If it is the distance far from the wood then you have a plumbed workpiece. This is especially useful for door and window fitting.
While working with metals, you might need a magnet. Some tools come with a magnet stuck to them. Others don’t have that so you have to improvise. You can use duct tape to hold it in position or you might just put the thing on to the bar and let the string hang from one edge.
After you have decided how to attach it to surfaces, the first thing you need to know that the plumb-bob is basically a pendulum which you are trying to keep steady. This is especially hard when you are working outside and the wind just sways the thing again and again.
A simple fix is to use your hand to make a shelter for the bob. This will decrease the wind effect and reduce fluctuations. The other thing is to use a finger or two to keep it steady. This will require patience. Once you have an accurate point, you drop the tip on the surface. This will keep it steady. You will also have to mark the spot for future use.
How to tie a plumb-bob?
This is an important question because tying the thread wrong will result in a tilted bob. This will harm the accuracy of the measurement.
Most of the plumb-bobs in the market have the hook at the end and you just have to make a knot on the ring-shaped hook. Make sure that the knot is not too tight. If the knot is loose, it will move as you hang the bob so it gets along the vertical line. It is important that it is not tight.
What does it mean for a wall to be plumbed?
A wall is plumbed when it is vertical to the horizon. Notice that it is not vertical to the ground because the ground itself can be sloped. A wall is plumbed when its center of gravity is at the center of its width. This way, the weight of the wall will be carried by the lowest bricklayer and it will stand balanced on its foot.
Would a plumb-bob work on an airplane determine a level horizon?
It will work only if the airplane is going at a straight line and at a constant speed. These are hardly the situations with airplanes. Fluctuations of speed and constant turning make it very difficult for plumb-bobs to work on an airplane.
They will only work properly in a real world situation, when the plane is on the ground, not moving.
From the list of five products that we have reviewed, the Tajima PZB-400G is the best plumb-bob for a professional. Though it costs more than the others, its adaptability to different situations makes it a versatile tool for any workman.
The engineers can use it for accurate measurements and also a carpenter can use it for fitting wooden panels or doors.
The tool provides a wide range of features and the Japanese have truly done an excellent job at producing it. The built quality is very impressive.
If you are new at your line of work then you should not be wasting money on a precision tool, rather, you can use the General Tools 790-8 Hexagon Steel Plumb-bob. Though it is simple, it is very reliable.
Though the plumb-bob is old equipment, it has lived through the passage of time. The people have used to make the pyramids with it in the past. Now they are being used to build sky-scrapers. It has helped build our modern cities and proven its worth countless times.
It is cheap, reliable and simple. It also lasts a very long time. A plumb-bob is a tool which has shaped the era of tall and mighty buildings and you can own one; it is a symbol of perfection and precision.
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