Vernier Caliper: What Is It And What Is It For?

The caliper or caliper is a measuring tool that is used to obtain very precise measurements, both from its internal and external faces. Usually, it is used for mechanical work to know the exact size of some parts such as screws, shafts or gears. Let’s see what a gauge is and what it can be used for.

Mechanics and craftsmen, who have to perform precision work, will know well what a caliper or caliper is. These tools allow very precise measurements to be obtained , since they have several millimeter rulers on the inside and also on the outside.

In this sense, the caliper, also called caliber or vernier, has two sets of calipers, some on the inside and others on the outside. Each one has a different use, for example, those at the back are used to measure interiors, while the front ones, somewhat larger, are used to measure outside diameters. On the other hand, among the parts of the caliper, a depth probe stands out, with which very precise measurements of blind holes, cavities or grooves can be obtained.

It will be better to go in parts, let’s start at the beginning.

What is a vernier caliper?

The caliper, vernier or caliper, is a very precise measuring tool, which has a pattern to compare with the object that needs to be measured. Usually, it is used to obtain the measurements of the diameters, both exterior and interior of the pieces, with a precision greater than that of a common rule.

How accurate is a gauge?

The caliper or caliper has a precision of one tenth of a millimeter , that is, it can divide a millimeter into ten parts. In this sense, it is almost 100 times more accurate than a common tape measure . On the other hand, the digital vernier caliper can reach a precision of one twentieth of a millimeter, that is, it can even divide a millimeter into 20 parts.

Where does the name caliper come from?

Before the advent of the metric system, measurements were taken in feet, spans, or cubits. This system had a problem and that is, how long is a foot? Well, as you can imagine, the feet did not measure the same in England as in Spain, in the same way that the feet of two different people do not measure the same. It was for this reason that the measurement of the king’s foot of each country was used as a reference , that is: a royal foot.

On the other hand, if you need to go from foot to meter and you wonder how much a foot is currently; the answer is that a foot would be about 0.3048 meters.

What is a gauge for?

As we have already mentioned, its most basic use is to measure diameters and depth , usually in mechanical parts and other types of objects that require great precision.

In this sense, it is important that the objects to be measured are rigid, since the measurements are taken with its two sets of pliers. If the object is soft or moldable, the measurements will not be accurate, as the object is deformed . For this reason, some of the most common uses for a vernier caliper is to measure the diameter of a tapping screw, find the inside diameter of a nut, or measure the depth of an engine cylinder.

Although a ruler could be used to obtain the diameter or depth of these parts, the gauge is a tool that offers much higher precision. This is very important, since an error of two tenths of a millimeter in these parts could cause serious problems during assembly or even serious accidents.

In short, it is a highly appreciated tool for machining jobs, both for the lathe and for the milling machine, as well as for automotive mechanics.

What are the parts of the vernier caliper?

The caliper or caliper is made up of a fixed part and a moving part. It also has an inner jaw, with which the outer diameters are measured, and an outer one, with which the inner diameters are measured. Finally, between the parts of the foot, we find that in the rear part it has a depth probe, with which the blind holes are measured.

Fixed part parts:

  • Main scale of measurements, which can appear in millimeters, inches, or both.
  • The fixed mouth of both sets of jaws.
  • In the digital caliper there is also the LCD screen in which the measurements are displayed.

Moving part parts:

  • The movable jaws of the two sets of jaws.
  • Depth probe.
  • Nonio the auxiliary scale.
  • Brake to block the caliper opening.

How to use the gauge

If you want to find out how the gauge works, you should know that it is a very simple tool, since the gauges have two sets of tweezers of different sizes, as well as a depth probe. The larger set of clamps is used for external measurements, while the smaller ones are for internal measurements, and the probe for depth.

In this sense, to measure with the large calipers, the object must be positioned on the inside and not at the ends, which have a bevel. This is because the bevel can distort the measurement. On the other hand, the interior measurements are taken with the small tweezers, which must be placed between the two interior walls and open until they rest on the inside of the object.

Also, the small calipers can be used to find step measurements. To do this, the caliper should be supported on the upper part of the step and opened, until the clamp is flush with the descending part.

Finally, to measure the depth, simply rest the lower part of the gauge on the hole and open the probe until it touches the lower part.

On some occasions, when making a measurement, you will find a certain lag between the main measurement and the one that appears on the vernier. If this happens, you will only have to add the lag between the two measurements to obtain a verification measurement. That is, if the main measurement is 9 mm and that of the vernier is 0.8 mm, the precise result will be 9.8 mm.

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