Vernier Calipers

Vernier Calipers

Vernier calipers are precision measuring instruments used in engineering workshops to measure internal dimensions, external dimensions, and depths of objects. They provide greater accuracy than ordinary measuring scales and are widely used in fitting shops, machine shops, and inspection departments.

Principle of Vernier Calipers

The vernier caliper works on the principle of the Vernier scale. The Vernier scale allows accurate measurement by comparing two scales: the main scale and the vernier scale. The difference between one main scale division and one vernier scale division gives the least count of the instrument.

Construction

The vernier caliper is usually made from stainless steel to ensure strength and accuracy. It consists of a fixed main scale and a sliding vernier scale attached to movable jaws.

Main Parts

• Main Scale: The fixed scale graduated in millimeters or inches.
• Vernier Scale: A sliding scale that provides fractional measurement.
• Outside Jaws: Used for measuring external dimensions.
• Inside Jaws: Used for measuring internal dimensions.
• Depth Rod: Used to measure the depth of holes and slots.
• Locking Screw: Used to lock the movable jaw in position.

Graduations

The main scale is graduated in millimeters (metric) or inches (English system). The vernier scale is divided into equal parts, allowing measurements up to a least count of 0.02 mm in metric instruments.

Reading a Vernier Caliper

• Note the main scale reading just before the zero of the vernier scale.
• Find the vernier scale division that coincides with a main scale line.
• Multiply that number by the least count.
• Add this value to the main scale reading.

Uses

• Measuring external diameters.
• Measuring internal diameters.
• Measuring depth of holes or slots.
• Inspection work in machine shops.

Care and Maintenance

• Clean the instrument after use.
• Avoid dropping the caliper.
• Keep measuring surfaces free from dirt.
• Store it in a protective case.
• Apply light oil to prevent rust.

Vernier Bevel Protractor

A vernier bevel protractor is a precision instrument used to measure angles accurately. It is widely used in machine shops, tool rooms, and inspection departments.

Construction

The instrument consists of a circular scale, a movable blade, a vernier scale, and a locking mechanism. The blade rotates and can be fixed at a particular angle.

Graduations

The main scale is graduated in degrees from 0° to 360°. The vernier scale allows readings up to 5 minutes of an angle.

Reading

• Note the main scale degree reading.
• Identify the vernier division that coincides with a main scale line.
• Add the vernier reading to the main scale reading.

Uses

• Measuring angles of machine components.
• Checking angular accuracy.
• Setting angles during machining.

Care and Maintenance

• Handle carefully to avoid damage.
• Keep scales clean and free from scratches.
• Store in a protective case.

Dial Vernier Caliper

The dial vernier caliper is an improved version of the standard vernier caliper. Instead of reading a vernier scale, the measurement is shown on a dial indicator, making the reading process easier and faster.

Features

• Dial indicator for easy reading.
• Measures external, internal, and depth dimensions.
• Higher accuracy compared to ordinary calipers.

Uses

• Precision measurement in workshops.
• Quality inspection of components.

Care and Maintenance

• Avoid shocks to the dial mechanism.
• Keep the instrument clean.
• Store properly after use.

Digital Vernier Caliper

A digital vernier caliper is a modern measuring instrument with an electronic display that shows measurement values directly. It eliminates manual reading errors and provides faster measurements.

Features

• Digital LCD display.
• Metric and inch conversion.
• Zero-setting function.
• High precision measurement.

Advantages

• Quick and accurate readings.
• Easy to use.
• Reduces human error.

Care and Maintenance

• Keep the display clean.
• Replace batteries when needed.
• Avoid moisture and dust.
• Store safely in a case.

Vernier Height Gauge

A vernier height gauge is a precision measuring instrument used for marking and measuring vertical heights of objects. It is commonly used with a surface plate for accurate measurement and layout work.

Material

Vernier height gauges are generally made from hardened steel or stainless steel to ensure strength, durability, and resistance to wear.

Construction

The height gauge consists of a heavy base that rests on a surface plate, a vertical graduated scale, and a sliding vernier scale attached to a scriber.

Main Parts

• Base
• Main Scale
• Vernier Scale
• Slider
• Scriber
• Fine Adjustment Screw
• Locking Screw

Graduations (English and Metric)

The main scale may be graduated in millimeters (metric system) or inches (English system). The vernier scale allows precise measurement of fractional values.

• Metric least count: usually 0.02 mm
• English least count: usually 0.001 inch

Uses

• Measuring vertical height of components.
• Marking lines parallel to a surface plate.
• Inspection and layout work.
• Checking height differences between parts.

Care and Maintenance

• Always use the gauge on a clean surface plate.
• Keep the base and scriber clean.
• Avoid dropping the instrument.
• Apply oil to prevent rust.
• Store properly after use.