Precise levelling is important while building a strong and dependable construction. A dumpy level is a simple yet effective equipment employed in building and surveying to measure height variations between locations. It helps in ensuring that roads, buildings, and other constructions have been erected on a level ground.
Brick & Bolt achieves precision and quality in all its projects by employing effective tools such as the dumpy level. In this article, we will discuss the uses, applications, and why a dumpy level is required in construction.
What is a Dumpy Level?
A dumpy level, also called an automatic level or builder’s level, is a tool used to measure the height of land. It may look difficult to use, but once you learn how to set it up and take measurements, it becomes easy to use.
William Gravatt invented it in 1832. It uses a telescope and a bubble level to determine the correlation between two or more points on a level surface. A dumpy level can be accurate up to 1:4000 for every 100 meters. It helps to find the height and distance between different points on the land.
Components of a Dumpy Level
The components of a dumpy level are as follows:
Telescope in Dumpy Level
The telescope in a dumpy level helps to see far objects in a straight line. It stays fixed to the vertical spindle and moves with it.
Parts of the Telescope
- Eye Piece – The observer looks through it to see objects. It has a magnifying glass for clear readings.
- Objective Lens – It is at the front of the telescope and has curved lenses that show an upside-down image.
- Diaphragm – It is in front of the eyepiece and has crosshairs to help with precise viewing.
- Focusing Screw – It helps to make the image and crosshairs clear.
- Ray Shade – It blocks sunlight and other bright light from disturbing the view.
Bubble Tubes
There are two bubble tubes, longitudinal and cross, to check if the instrument is level. The instrument is level when both bubbles are in the centre.
Compass
A circular compass under the telescope shows the magnetic direction of a line. The pointer is set to zero when facing north.
Vertical Spindle
This part is at the centre of the instrument and lets the telescope rotate sideways. It also connects the instrument to the tripod.
Tribrach
A plate that runs parallel to the levelling head is called a tribrach. Levelling screws adjust it to keep the instrument horizontal.
Foot Screws
These screws adjust the tribrach plate to make the instrument level.
Leveling Head
Also called a trivet, it has two parallel triangular plates with grooves for foot screws. It helps in leveling.
Tripod
The tripod holds the instrument with three adjustable legs. The legs can be solid or hollow. Steel shoes at the bottom keep the instrument stable on the ground.
How to Set Up a Dumpy Level?
First, secure the dumpy level on the tripod using clamp screws. To get a convenient height, space out the tripod legs. Level the third leg until the bubble in the bubble tube is central after firmly attaching the other two legs to the ground. This ensures that the instrument is properly levelled for accurate measurements.
How to Use a Dumpy Level for Land Surveying?
To conduct a dumpy level survey, the following tools are needed:
- Dumpy Level
- Tripod
- E-meter staff or English staff
An assistant is also needed to help with the survey. Once everything is ready, follow these steps:
1. Set Up the Tripod
- Adjust the tripod height until it reaches eye level.
- Move the tripod legs to a balanced position for stability.
- Press the tripod legs into the ground to keep them firm.
2. Fix the Dumpy Level on the Tripod
- The dumpy level should be placed on top of the tripod.
- Tighten it using the foot screw to secure it.
- Be careful, as the level head is very sensitive.
3. Level the Dumpy Level
- Use the foot screws (levelling screws) to adjust the instrument.
- Keep adjusting until the bubble in the alignment marker is in the centre.
4. Take Measurements
- The operator looks through the telescope’s eyepiece.
- The assistant holds the E-meter staff vertically at the point being measured.
- The staff has both imperial and metric units. The “E” shape marks five centimeters.
5. Record Elevations
- The instrument helps measure the height of different points.
- The survey usually starts from a benchmark (a point with a known height) or an arbitrary point (a point with an assumed height).
These recorded readings are known as field measure data, which are essential for ensuring precision in levelling and further calculations during site planning.
Applications of Dumpy Level in Construction
Some uses of dumpy level in construction are as follows:
- It helps to find the height of different points in surveying.
- It is used in construction to position structures correctly.
- Surveyors use it to make land surfaces level.
- It helps build roads, pipelines, railways, and drainage systems.
- The built-in compass helps find directions.
Advantages of Using a Dumpy Level
Several benefits of using a dumpy level are as follows:
- The dumpy level is easy to use.
- It is cheaper than the theodolite and total station.
- It needs very few adjustments to set up.
- It has strong optical power.
- It gives very accurate readings.
- The bubble can be adjusted from any side using any three screws.
- Auto levels have a built-in system that automatically adjusts the line of sight when needed.
Disadvantages of Using a Dumpy Level
Some limitations of using dumpy level include:
- It cannot measure vertical angles, only the horizontal plane. Horizontal angles are not very accurate.
- It requires two people—one to look through the lens and another to hold the measuring staff.
- Using a dumpy level needs math skills to calculate ratios and offsets. The accuracy depends on the person doing the calculations.
- It only works in good lighting conditions. It cannot be used at dusk or in dark areas.
- If not maintained properly, it can become inaccurate. Regular calibration and servicing are needed.
- It is less flexible than laser levels. It does not work with machines and can measure only one point at a time. However, laser levels can be used by many people at the same time.
Conclusion
A dumpy level is essential for guaranteeing accuracy in building projects. It is a necessary instrument for high-quality work since it assists surveyors and builders in creating sturdy, level constructions. At Brick & Bolt, we believe the best equipment and methods should be used to create sturdy, long-lasting structures. Gaining a knowledge of how a dumpy level operates will enable you to recognise the significance of accurate levelling for every construction project.