Bevel Protractor Definition | Parts | Working, application, Uses |

what is bevel protractor ?

A bevel protractor is a precision measuring instrument used for measuring and marking angles. It consists of a circular protractor dial with a graduated scale ranging from 0 to 360 degrees. The dial is attached to a base plate that can be swiveled and locked at any desired angle.

Bevel Protractor

The bevel protractor is primarily used in engineering, metalworking, and woodworking applications. It is commonly employed for tasks such as setting and measuring angles for machining operations, layout work, inspection, and quality control.

To use a bevel-protractor, the base plate is positioned on the surface to be measured, and the dial is rotated to align with the reference angle. The locking mechanism is then engaged to secure the protractor in place, allowing for accurate angle measurements.

Some bevel-protractors also feature a vernier scale, which provides additional precision by allowing readings to be taken to a fraction of a degree.

Overall, It is a versatile tool that enables accurate angle measurements and helps ensure precise and consistent results in various industries.

Must Read : Types of Shafts

parts of bevel protractor

It consists of several parts that work together to accurately measure angles. Here are the key components of a bevel protractor based on the information provided in the article:

Parts of bevel protractor
  1. Swivel Plate:
    The swivel plate is a rotating component that houses the vernier scale. It allows the user to adjust and set the desired angle for measurement.
  2. Magnifying Glass:
    A magnifying glass is integrated into the swivel plate, specifically on the vernier scale. It aids in better visibility and precise reading of angle values on both the main scale and the vernier scale.
  3. Vernier Scale:
    The vernier scale is attached to the swivel plate and moves along with it. It provides additional accuracy to angle measurements by indicating the remaining angle in minutes. The Vernier scale consists of 12 divisions on each side of the zero mark, with each division representing 5 minutes. This results in a total of 60 minutes on each side of the zero mark.
  4. Angle Locking Screw:
    The angle locking screw is used to secure the bevel protractor at a fixed angle. By tightening this screw, the swivel plate is held in place, ensuring that the desired angle can be measured without any movement or disturbances.
  5. Dial:
    The dial serves as the base of the bevel protractor, providing stability and support for the other components. It is on this dial that the main scale, or dial scale, is marked.
  6. Dial Scale:
    The dial scale is a crucial part of it. It is marked with angle graduations from 0 degrees to 360 degrees. Every tenth degree is indicated on the dial scale, and it is divided into four sections of 90 degrees each.
  7. Blade:
    The blade is made of high carbon steel and is a thin, elongated piece. It can be either 150 mm or 300 mm in length, depending on the specific bevel protractor. The blade is used to establish contact with the workpiece and enables angle measurements. One end of the blade is angled at 45 degrees, while the other end has a 30-degree angle, allowing for direct measurement of those angles.
  8. Blade Lock Screw:
    The blade lock screw is used to secure the blade at a fixed position. It ensures that the blade remains in place when determining the required length along the surface of the workpiece.
  9. Stock:
    The stock is an integral part of the bevel protractor and serves as one of the contact surfaces during angle measurement. It is connected to the dial and rotates along with it as the angle is adjusted. When measuring angles, one side of the workpiece is placed in contact with the stock, while the other side is in contact with the blade. The blade fits into a slot in the stock, allowing for precise and stable measurements.

working of bevel protractor

Firstly, the workpiece, whose angles are to be determined, is positioned between the blade and the stock of the bevel protractor. One side of the surface, which measures the angle, is placed in direct contact with the blade, while the other sides make contact with the stock.

Once the workpiece is properly aligned with the blade and the blade is correctly positioned on the workpiece, it is secured by tightening the blade locking screw. Subsequently, when the measured surface fully aligns with the stock and blade, the angle is fixed by tightening the angle locking screws.

Now, let’s observe the values on the main scales that align with the zero point on the Vernier scale. The value we read from the main scale provides the angle in degrees. More precisely, the angle on the main scale appears just before the zero points on the Vernier scale.

To achieve a more accurate measurement of the angle, we will now determine the remaining angle in minutes. To accomplish this, we examine the Vernier scale and locate the line that perfectly aligns with the line on the main scale.

Once we have identified that line, we note its position on the Vernier scale. The measurement in minutes for the angle is calculated by multiplying the position of the corresponding line on the Vernier scale by five.

Finally, we record the measured angle in degrees and minutes, using the bevel protractor. In this manner, we are able to obtain a highly precise measurement of the angle using a bevel protractor.

how to use bevel protractor step by step

The working of a bevel protractor involves a simple and straightforward process. Here are the steps involved:

  1. Set the Base Plate: Place the base plate of the bevel protractor on the surface or workpiece where you want to measure or set an angle. Ensure that the base plate is stable and securely positioned.
  2. Align the Blade: Rotate the blade or arm of the bevel protractor to the desired angle. This is typically done by loosening the locking mechanism, adjusting the blade to the required position, and then tightening the lock to secure it in place.
  3. Read the Angle Measurement: Look at the circular protractor dial of the bevel protractor. The dial is marked with a graduated scale ranging from 0 to 360 degrees. Read the angle measurement indicated by the aligned blade or arm.
  4. Vernier Scale (if applicable): If the bevel protractor has a vernier scale, which provides finer subdivisions of the main scale, you can use it to obtain more precise readings. Align the vernier scale with the main scale and note the additional measurement indicated by the vernier.
  5. Magnifying Lens (if applicable): Some bevel protractors have a magnifying lens built into the dial. If necessary, use the lens to enhance the readability of the scale, especially when dealing with smaller graduations.
  6. Lock the Measurement: Once the desired angle is read and recorded, you can lock the blade or arm in place using the locking mechanism. This ensures that the angle remains fixed and prevents accidental movement during further measurements or operations.

It’s important to handle the bevel protractor with care, ensuring that it is positioned correctly and that the blade or arm is aligned accurately. Any misalignment or errors in reading or locking the angle can affect the measurement accuracy. Regular calibration and maintenance of the bevel protractor can help maintain its accuracy over time.

vernier bevel protractor least count

The least count of a Vernier bevel protractor refers to the smallest angle that can be accurately measured using the instrument. It represents the degree of precision or resolution of the protractor’s measuring scale.

In the case of a Vernier bevel protractor, the least count is determined by the division on the Vernier scale that aligns with a division on the main scale or dial scale. The Vernier scale typically has divisions that are smaller than those on the main scale, allowing for more precise angle measurements.

To calculate the least count of a Vernier bevel protractor, you need to consider the division size on both the Vernier scale and the main scale. Let’s assume that on the Vernier scale, each division represents 5 minutes (1/12th of a degree), and on the main scale, each division represents 1 degree.

To find the least count, you divide the smallest division on the main scale by the total number of divisions on the Vernier scale. In this case, since the Vernier scale has 12 divisions, the least count would be:

Least Count = Smallest Division on Main Scale / Total Divisions on Vernier Scale
= 1 degree / 12 divisions
= 1/12 degree or 5 minutes

Therefore, the least count of this particular Vernier bevel protractor would be 1/12th of a degree or 5 minutes. This means that the instrument can measure angles with a precision of 5 minutes, allowing for more accurate angle measurements compared to a protractor without a Vernier scale.

How to read bevel protractor by example

How to read bevel protractor

Sure! Here’s a simplified version:

In the figure, we can see that the main scale aligns with the 0 line on the vernier scale, and it shows 80 degrees.


Main Scale Reading = 80 degrees

Now, if we look closely, we can see that the 7th line on the vernier scale matches with a line on the main scale.

Each line on the vernier scale represents 5 minutes.


Vernier Scale Reading = 7 lines × 5 minutes = 35 minutes

To get the final reading, we add both values together.

Vernier Bevel-Protractor Reading = 80 degrees + 35 minutes

Vernier Bevel-Protractor Reading = 80 degrees + (35/60) degrees

Vernier Bevel-Protractor Reading = 80.58 degrees

To take care of the Vernier bevel-protractor:

  1. Always clean it before using it.
  2. After use, store it in a safe place with a thin coating of oil.

In summary, we discussed the parts of a vernier bevel protractor, how to calculate its least count, and how to read the measurements. We also covered some care and maintenance tips.

I hope you found this topic enjoyable and informative!

bevel protractor is used for

A bevel protractor is primarily used for measuring and setting angles accurately. It is commonly used in various industries, including metalworking, woodworking, engineering, and construction.

  1. Angle Measurement: The main purpose of a bevel protractor is to measure angles with high precision. It allows users to determine the angle between two surfaces or the inclination of an object.
  2. Layout and Marking: It often used for layout and marking tasks. They can help in marking angles on workpieces or transferring angles from one object to another for accurate cutting, drilling, or machining.
  3. Tool Setup: It is useful for setting up tools and machinery at specific angles. They enable precise adjustment of saw blades, milling cutters, drill bits, and other cutting or shaping tools to achieve the desired angle of operation.
  4. Inspection and Quality Control: In industries where angle measurements are critical for quality control, It is used to verify the accuracy of manufactured parts or components. They help ensure that angles meet the required specifications and tolerances.
  5. Angle Alignment: It can assist in aligning objects or structures at specific angles. This is useful in applications such as aligning machine parts, aligning surfaces for welding, or setting up architectural features.
  6. Educational and Training Purposes: these are commonly used in educational settings, such as technical schools and vocational training programs, to teach students about angle measurement and geometric principles.

Overall, It is a versatile tool that enables accurate angle measurement and facilitates various tasks that require precise angular positioning or alignment.

applications of bevel protractor

Bevel protractors find applications in various industries and fields. Some common applications of bevel protractors include:

  1. Engineering and Machining: It frequently used in engineering and machining industries to measure and set precise angles for tasks such as milling, drilling, lathe operations, and metal fabrication. They ensure accurate alignment of workpieces and tools, leading to quality machining results.
  2. Woodworking and Carpentry: In woodworking and carpentry, It is used to measure and mark angles for cutting, joinery, and furniture making. They help ensure precise angle cuts for miters, bevels, and compound angles, enabling accurate assembly and fitting of wooden components.
  3. Quality Control and Inspection: It is utilised in quality control and inspection processes to verify the accuracy of machined or manufactured parts. They allow inspectors to measure and confirm angles specified in blueprints or design requirements, ensuring compliance and precision.
  4. Layout and Construction: In construction projects, bevel protractors assist in layout work, where precise angles need to be marked or transferred onto building materials. They are used for tasks such as setting roof pitch angles, aligning walls, and determining angles for staircases.
  5. Education and Training: It is commonly used in technical education and training programs to teach students about angles, geometry, and precision measurement. They help students understand and practice concepts related to angles and their applications in various fields.
  6. Metalworking and Welding: It is valuable tools in metalworking and welding applications. They aid in measuring and setting angles for accurate welding joint preparation, pipe fitting, and structural fabrication.
  7. Automotive and Aerospace: In automotive and aerospace industries, bevel protractors are employed for tasks such as aligning and adjusting engine components, measuring suspension angles, and setting up precise angles for aerodynamic surfaces.

These are just a few examples of the applications of bevel protractors. Their versatility, accuracy, and ease of use make them essential tools in many industries that require precise angle measurements and markings.

advantages of bevel protractor

Bevel protractors offer several advantages that make them valuable tools for various applications. Here are some of the advantages of using a bevel protractor:

  1. Accurate Angle Measurement: It provide precise measurements of angles. With a graduated scale and often a vernier scale, they allow for accurate readings to a fraction of a degree, ensuring high measurement accuracy.
  2. Versatility: It is versatile tools that can measure and set angles in a wide range of applications, including engineering, machining, woodworking, construction, and more. They can be used for both internal and external angle measurements.
  3. Easy to Use: It is relatively simple to use. They have a straightforward design and intuitive operation. Users can easily position and lock the protractor at the desired angle, making it convenient for quick and efficient measurements.
  4. Portable and Compact: It is typically compact and lightweight, making them easy to carry and transport. Their portable nature allows for convenient on-site measurements in different locations or work environments.
  5. Durable Construction: It is often made from robust materials, such as stainless steel or hardened steel, ensuring their durability and longevity. They can withstand rugged working conditions and repetitive use without compromising accuracy.
  6. Precise Angle Settings: The locking mechanism in bevel protractors enables precise angle settings. Once the desired angle is set, the locking mechanism securely holds the position, preventing any accidental movement or changes during measurement.
  7. Magnifying Lens: Many bevel protractors feature a magnifying lens that enhances the readability of the scale and vernier. This makes it easier to read and interpret measurements, especially when dealing with smaller graduations.
  8. Educational Value: It is commonly used in educational settings to teach students about angles, geometry, and measurement principles. They help students develop a better understanding of angles and their applications.

Overall, the advantages of bevel protractors include their accuracy, versatility, ease of use, portability, durability, and educational value. These factors contribute to their widespread use in various industries and their effectiveness in achieving precise angle measurements.

disadvantages of bevel protractor

While bevel protractors offer several advantages, there are also some limitations or disadvantages associated with their use. Here are a few disadvantages of bevel protractors:

  1. Limited Range: It has typically have a limited range of measurement. The circular scale usually ranges from 0 to 360 degrees, which may not be sufficient for measuring larger or unconventional angles that fall outside this range.
  2. Restricted Access in Confined Spaces: The size and design of bevel protractors may limit their use in tight or confined spaces. The base plate and blade may obstruct access to certain areas, making it challenging to measure angles in such conditions.
  3. Reliance on Visual Alignment: It rely on visual alignment for accurate measurements. While they often have clear markings and a magnifying lens, human error in aligning the protractor with the reference angle can introduce slight inaccuracies.
  4. Limited Precision: While bevel protractors offer reasonably accurate measurements, they may not provide the same level of precision as more specialized tools, such as digital angle finders or precision squares. The graduations on the scale and vernier may have limitations in achieving extremely precise measurements.
  5. Limited Functionality: It is primarily focus on measuring and setting angles. They may lack additional features or capabilities found in other measuring tools. For example, they may not have built-in levels for checking flatness or inclination.
  6. Vulnerability to Damage: Although bevel protractors are often made from durable materials, they can still be susceptible to damage if mishandled or subjected to excessive force. Accidental drops or impacts can affect the accuracy and functionality of the protractor.
  7. Cost: Depending on the quality and features, bevel protractors can vary in price. Higher-quality models with advanced features may be relatively expensive, which could be a disadvantage for those on a tight budget or with limited resources.

It’s important to consider these limitations and factors specific to bevel protractors when choosing the appropriate measuring tool for a particular task or application. In some cases, alternative measuring instruments may be more suitable for achieving specific requirements or higher levels of precision.

Source : Wikipedia

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