What is a vernier caliper?
A vernier caliper is a measuring device used to precisely measure linear dimensions.
It is a very useful tool to use when measuring the diameter of a round objects like cylinders because the measuring jaws can be secured on either side of the circumference.
Vernier calipers have both a fixed main scale and a moving vernier scale.
The main scale is graduated in either millimetres or tenths of an inch.
The vernier scale allows much more precise readings to be taken (usually to the nearest 0.02mm or 0.001 inch) in comparison to a standard ruler (which only measures to th nearest 1mm or 0.25 inch).
The vernier scale was invented by French mathematician Pierre Vernier in 1631.
As part of the vernier caliper, it is used together with the main scale, and helps to provide very precise measurements.
Vernier calipers usually show either imperial or metric measurements, but some measure in both.
The range (sometimes called maximum capacity) of a vernier caliper is the difference between the largest value and the smallest value that the caliper can measure. It is equal to the length of the main scale.
Most vernier calipers have a range of 6 inches (300mm), although calipers with smaller and larger ranges are also available.
Resolution (vernier reading)
The resolution (or vernier reading) of a vernier caliper is the smallest distance that the caliper can measure.
The resolution of imperial vernier calipers is usually 0.001 in, whereas the resolution of metric calipers is either 0.05mm or 0.02mm.
A caliper's resolution is indicated at the end of the vernier scale.
Instrument error or tolerance
Instrument error refers to how accurate a vernier caliper is.
Vernier calipers, like micrometers, are tools used for low tolerance measuring. Low tolerance measuring tools provide very accurate measurements, with a small margin for error.
The instrument error of most vernier calipers is +- 0.03mm (+- 0.0015 in), making the tool very useful if you are looking for a high level of precision in your measurements.
Most verniers are capable of measuring outside dimensions, inside dimensions and depth.
Some calipers, which incorporate quadri feature, can also be used to take step measurements.
What is the difference between a dial caliper and a vernier caliper?
Dial calipers and vernier calipers provide measurements of the same accuracy. The primary difference between the two tools is the way these measurements are displayed.
The dial on the dial caliper makes it an easier tool to read. However, many people are used to the more traditional vernier scale and so prefer to use the vernier caliper.