How to Read Vernier Caliper Measurement?

To read vernier caliper measurements in millimeters or inches, you need to know some basic reading steps. Before moving ahead, I hope you know what is cm, mm, or inch. However, zero figure readings like 25 mm, 50 mm, or 100 mm are fine.

But, when you get 25.3 mm or 100.2 mm, it becomes important for you to know how to read 0.2 or 0.5 mm or similar measurements on a Vernier Caliper.

Verniers are an essential tool for obtaining accurate measurements in mechanical engineering and other fields that require precision. Below is a very easy guide on how to use a vernier caliper effectively:

How to Use a Vernier Caliper?

Vernier caliper image

Vernier calipers have two main scales:

  • Main Scale: The main scale is marked in millimeters (mm), or inches.
  • Vernier Scale: There is a secondary scale that slides along the main scale, and provides you with more accurate measurements (0.1, 0.2 to 0.9).

A caliper has two sets of jaws and a depth probe:

  • Outer Jaws: The outer jaws measure the outside dimensions of any object (e.g., diameter, thick, or width).
  • Inner Jaws: The inner jaws measure inside dimensions (e.g., hole diameter).
  • Depth Probe: Measure the depth of a hole or recess. You have to move the Vernier jaw to measure with the depth probe.

How to Read Vernier Caliper Measurement?

First, you need to read the measurement of the main scale of the vernier caliper, it can be in mm or inches. If you find the measurement a little higher than the mark then check on the vernier scale at which specific point it touches.

In the above vernier caliper image, each division on the vernier scale represents 0.2 mm. However, on some vernier divisions may be 0.1 mm.

To read vernier caliper measurements, you need to follow the steps given below:

1. Outer Measurements:

Before taking measurements, make sure the Vernier is calibrated. Close the jaws gently and check whether the zero on the main scale aligns with the zero on the vernier scale. Also, clean both the caliper and the object, as this can help obtain an accurate measurement.

  1. Open the outer jaws and place the object between them.
  2. Close the jaws gently until they touch the object.

Note: Avoid excessive force, which can distort the object or the caliper, and make sure the object is aligned perpendicular to the jaws of the caliper to avoid skewed readings.

2. Inner measurements:

The inner jaws are used to measure the inside diameter of any object.

  • Open the inner jaws slightly less than the inner diameter of the object.
  • Insert the jaws into the hole and open them gently until they touch the inner surfaces.
  • Make sure the jaws are correctly aligned within the hole so that no errors occur.

3. Depth Measurement:

Advance the depth probe from the end of the caliper.

  • Insert the depth probe into the hole and make it contact the bottom.
  • The main part of the caliper must be perpendicular to the surface for accurate readings.
Main Scale Reading:

Look at the main scale and identify the last whole millimeter mark before the zero of the vernier scale. This is the main scale reading.

Vernier Scale Reading:

Find a line on the vernier scale that aligns exactly with a line on the main scale. The number of this aligned line on the vernier scale gives the additional fraction of a millimeter to add to the main scale reading.

Combine Readings:

Add the main scale reading and the vernier scale reading to get the total measurement (see reading example).

Reading Example

Suppose the main scale reading is 25 mm and the 6th line on the vernier scale is aligned with a line on the main scale. If each division on the vernier scale represents 0.02 mm, the vernier reading is:

6 × 0.2 = 0.12

The total measurement is – (25 mm + 0.12) = 25.12 mm

Digital Vernier Caliper

There are many types of verniers, but the digital vernier caliper is easier to read than others.

Digital Vernier caliper image

It has an electronic display that provides a digital readout of the measurement. So, it is more accurate and easier to use than a traditional vernier caliper with manual readings.

Tips for Accurate Measurements

Apply constant and light pressure to avoid deforming the object or the caliper while measuring. Make sure the caliper is properly aligned with the object. Misalignment can lead to significant errors.

  • Readability: Use good lighting and, if necessary, a magnifying glass to read the scale accurately.
  • Calibration: Calibrate your caliper regularly, if it is subjected to heavy use or falling.

By following the steps above, you can use a vernier caliper to read measurements with high precision. Proper operation and regular practice will increase your accuracy and confidence in using this essential tool.

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