# The Components of the Caliper and Their Functions

The caliper is a type of measuring instruments that works to determine the diameter, depth, and thickness of an object. It has an accuracy of up to 0.1 mm. This measuring instrument can function properly because it consists of various components that support each other with their respective functions. The following is a picture of a caliper and the names of the components.

The picture above is a vernier caliper. It is not enough just to know the name of the components, let alone the name on the picture. Down below is a complete explanation of the components of the caliper.

1. Vernier Caliper Main Base

The main base vernier caliper is the main component of the caliper to which all the other parts of the caliper are attached. If vernier caliper is a house, this main base is the foundation.

2. Main Scale

The main scale is a scale that is the main reference in reading the measurement results. In another sense, the main scale becomes the starting point of measurement. Usually, the main scale is expressed in units of cm.

In taking measurements with a caliper, this section is major concern before looking at the vernier scale. However, the accuracy of this scale is only up to 1 mm. For this reason, the measurement results become more accurate as it is necessary to look at the vernier scale when using the caliper.

It should be noted that there are other types of calipers that have two main types of scales, namely the units of cm and inches. In this article, the caliper in the picture contains only one unit.

3. Nonius Scale

The nonius scale or the vernier scale is a scale that is of secondary concern after seeing the main scale. After getting the initial number from the main scale reading, the nonius scale will read the decimal value from the measurement results with an accuracy of up to 0.1 mm. Both of these scales need to be considered and should not be reversed. The nonius scale will only be obtained if the main scale has been found.

Similar to the main scale, there are other nonius scales in the caliper that have two types of nonius scales, namely the units of mm and inches. The determination of the unit depends on the user of the caliper whether they want to use mm or inches.

4. Slider

A slider is a component of the caliper that works to move the caliper’s jaws so that they can widen or narrow according to the object being measured. It can be seen clearly in the picture that the slider is directly connected to the main base and there is a nonius scale in the slider.

5. Finger hook

You can see in the picture that the finger hook is shaped like a semicircle connected to the slider. This section serves as a place to move the slider. As the name implies, you can use it is enough with the help of one finger (thumb) to rotate the finger hook and result in shifting the slider.

6. Lock Screw

The lock screw works to hold the slider movement after a shift is made according to the size of the object. This means that after the slider is shifted and it is ensured that it matches the object’s size, it won’t budge. This way, an accurate reading can be made.

7. Fixed Inner Jaw (Rahang Dalam Tetap)

Rahang dalam tetap adalah bagian rahang yang terletak pada tempatnya, yang tidak dapat digerakkan karena menyatu dengan main base. Fungsi rahang ini adalah untuk mengukur diamater dalam suatu benda.

8. Moveable Inner Jaw

A sliding inner jaw is a jaw that can be shifted according to the size of the object. This jaw is attached to the slider so that it can be shifted wider and narrower for measurement needs. The sliding inner jaw works to measure the inner diameter of an object. This jaw works in conjunction with the fixed inner jaw.

9. Fixed Outer Jaw

The fixed outer jaw remains attached to the main case along with the fixed inner jaw. This jaw serves to measure the outer diameter of an object.

10. Moveable Outer Jaw

Similar to the moveable inner jaw, the moveable outer jaw is a jaw that can be shifted wider and narrower for measurement purposes. This jaw serves to measure the outer diameter of an object that works in conjunction with a fixed outer jaw.

11. Depth Rod

The depth rod is in the form of a long rod that is embedded in the main case so that only the ends are visible in the image. This section is directly connected to the slider so that the shift of the slider also affects the depth rod position.

When the jaw is closed, which means that the slider moves closer to the fixed jaw, this part will only show the edges, as in the picture. But when the jaw is opened, the depth rod will be more visible. The wider it is, the longer the depth rod appears. Depth rod is used to measure the depth of a hollow object/tube.

The components of the caliper need to be known, especially for those who frequently use them. They have their respective functions and an error in understanding their function when using the tool will result in measurement errors.

In addition, the components of the caliper above are not always exactly the same as other types of calipers. Given that there are different types of calipers, there may be a slight difference in the names of the components.