What Are Inside Vernier Calipers?
Inside Vernier Calipers are calipers specially designed to measure inside diameters. They are used in the same way as regular calipers, but they do not have a function for measuring external dimensions.
Analog calipers are read using a vernier scale, while digital calipers are the same as regular calipers in that the numerical value is directly displayed.
The feature of these calipers is that the jaws for measuring the inside diameter are longer, allowing the jaws to be inserted deeper into holes and tubes. Some manufacturers offer groove and point calipers that can measure stepped inside diameters and narrow grooves.
Uses of Inside Vernier Calipers
Inside Vernier Calipers are used to measure the inside diameter of holes and pipes.
Since the starting base point for measurement is not zero, it is necessary to create a base point using an inside width or ring gauge combined with a block gauge. position. Some digital Inside Vernier Calipers have an offset function, which allows the encoders base point to be adjusted freely, so the starting position can be set as desired.
Principle of Inside Vernier Calipers
The principle of Inside Vernier Calipers is similar to that of calipers for measuring inside diameters. As with ordinary calipers, the analog type reads the position where the main scale and the vernier scale coincide as a decimal point, while the digital type directly displays the numerical value of the scale attached to the main scale by means of an encoder.
Since measurement is often made by placing the jaw on the arc portion, it is necessary to pay attention to the pitching and yawing inclination of the scale. Tilting of the caliper or jaw can cause errors.
It should also be noted that calipers are not measuring instruments that follow the Abbe’s principle, so if the measuring pressure is too strong, the jaws will open in a “C” shape, making it impossible to read the correct value.
When measuring a wall with a small radius of curvature, the corner of the jaw will hit the inner wall and the tip will be separated from the inner wall, which may cause an error. If this kind of phenomenon occurs, the inside caliper cannot solve the problem, so another measuring device will be used.