Even if the Vernier caliper has various multiple uses to measure a range of diverse dimensions, it’s the method by which Vernier caliper reading is analyzed which always remains consistent throughout the measurement process.
The reading on a Vernier caliper is an combination of the value obtained from the main scale and the value evident on the moving Vernier scale.
Step 1 – LOOK AT MAIN SCALE
While undertaking a measurement, you must first analyze the reading on the main scale i.e. the immovable primary scale. Type of Vernier calipers such as Metric and Imperial scales have its own least count. Read more about Calculation of Least Count in Metric & Imperial Scales
The reading on the main scale is the number just before 0 division of the Vernier scale. For example in below image of Vernier Caliper, the main scale reading will be 27 mm.
Step 2 – DEDUCE READING AT VERNIER SCALE
Now, see at the given Vernier scale just after taking the main scale reading.
The Vernier scale of a metric or imperial caliper has again different least counts depending on the type of the Vernier Caliper. It is important to resolve the least count of the Vernier scale. Once the least count is resolved, see the division of the Vernier Scale actually coinciding Main scale Division. Read more about Vernier Caliper – Working, Calculation Of Least Count & Zero Error
The only division of the Vernier scale that actually coincides the Main scale marking is the actual reading of the Vernier Scale. In the image discussed above, the division count coinciding with the Main scale reading is 30 i.e. 6 marking of the Vernier scale. The least count of the scale discussed in example is 0.02. Therefore the Vernier scale reading is equal to the product of least of Vernier Caliper and the Division Coinciding the Main scale. Therefore 30 x 0.02 is 0.6 mm, which is the Vernier scale reading.
STEP 3 – SUM OF MAIN SCALE READING & VERNIER SCALE READING
In order to obtain total reading, put in together the value from the main scale reading and the final reading Vernier scale and add them together.
i.e. 27 + 0.6 = 27.60 mm
Therefore, the distance showed by the Vernier caliper is 27.60 mm in this example.
Also learn about Vernier Caliper Standard Practices for Reading its Scales & Vernier Caliper Practice for Finding Cylinders’ Dia & Volume