No construction or even minor repairs is possible without measuring instruments. Traditionally, they are roulettes or rulers.
However, situations often arise when you just can’t do it. For example, when it is required to measure the inner diameter of a hole or pipe, the outer size, the depth of the hole, etc., especially if high accuracy is required. Or how to find out the diameter of the drill if the markings on it are erased from time to time? There is nothing left but to measure its diameter with a vernier caliper.
The caliper was invented more than a hundred years ago and is still a popular measuring device. To determine how to properly measure with a caliper, you need to understand its structure.
Vernier caliper scale
The basis of this device is a ruler bar.
The main and auxiliary scales are applied to the caliper body. To get the exact size, the readings of both scales must be added up.
Entire millimeters are counted from left to right, the start is the zero mark of the vernier.
If it is necessary to find fractions of a millimeter, then you need to find that stroke of the nonius, which coincides with the stroke of the main scale. Then we multiply its serial number by the price of scale division.
As a result, we get the sum of two parameters - whole millimeters and fractions.
How to measure with a caliper
Before starting measurements, check the device for possible damage. If the calipers are skewed or worn, then they should not be used, since the results will be distorted.
Before measuring with a caliper (0.05 is the division value, for example), the lips of the device should be firmly pressed to the measured surfaces, avoiding distortions and pressing not too much. There should be no gaps between the part and the jaws.
To measure the depth of the hole, the depth gauge rod must be installed perpendicular to it, at the edge of the hole, pushing it all the way.
When measuring rounded parts, it is necessary to monitor the perpendicularity of the frame with respect to the part.
After measurement, the fixing bolt is tightened and the instrument reads.
To measure the diameter of the hole, the sponges are placed inside the measured hole at the maximum possible distance. This is achieved using a bar scale.
When working with a caliper, it is necessary to constantly monitor the coincidence of the zero mark on the vernier with the zero mark on the bar itself. If this cannot be achieved, then the device is clearly not suitable for operation.
When measuring the dimensions of soft parts on a caliper, it is useful to have a special trimmer screw. It allows you to bring the jaws to the part slowly, without clamping the surface.
Professional masters, speaking about the use of the caliper, do not cease to repeat that its accuracy is no worse than the classical tools used by their rulers and tape measures. How to measure with a caliper if the master is used to his line and trusts only her? Of course, we mean high-quality tools, issued exclusively at the factory, that have passed an accurate check for compliance with the standards of measuring instruments.
Roulettes, compasses and corners sold in the construction markets are unlikely to allow high-quality measurements. They can be used when not requiring high precision work.
Caliper device
Using a caliper, you can measure sizes from 0 to 15 cm. The accuracy of measuring the depth of the holes is 0.05 mm.
Designations:
- Measuring sponges for external dimensions - in addition to simple measurements, with the help of these sponges it is possible to lay a number of parallel lines.
- Measuring jaws for internal dimensions - with a bend outward.
- Sponges for marking.
- The frame is a rather complicated design, which consists of several parts. In order to reduce the backlash, a spring is located inside it. The adjusting screw achieves a smooth ride. In addition, on the frame there is a scale - auxiliary or nonius. The division price of most calipers is 1.9 mm. But this scale is not intended for direct measurements.
- Bar scale - marking in increments of 1 millimeter. The rod line is the body of the device itself. Usually in length is 150 millimeters. Made of alloy steel, it must be resistant to corrosion.
- Depth gauge - extendable bar.
- Nonius - a scale for measuring fractions of millimeters.
Sponge types
Most calipers have scissor lips. The question arises of how to measure the internal size with a caliper. The required size is determined directly on the scale, without additional calculations.
There are also stepped sponges. How to measure with a caliper with such features? In this case, if holes and grooves are measured, then their size should be added to the obtained sizes.
Design features of vernier calipers
Particularly noteworthy are devices with a dial gauge. For example, how to measure the diameter of the reinforcement with a caliper with a normal scale, if the operator has low vision? With the help of a device with a dial, you do not have to scrupulously deal with the combination of scales and calculate the fractions of millimeters.
The measurement results are immediately visible on the dial. This is especially convenient when you need to find the answer to the question of how to measure the diameter with a vernier caliper.
Different models may have different nonius values. Other design changes are possible. In any case, to obtain the correct values, the device must be kept clean and in good condition. In addition, it is necessary to constantly monitor the condition of the lubricant and do not forget to update it on time.
All measurements are, of course, carried out mechanically. And it is advisable to use calipers made at specialized manufacturers.
General recommendations when using the device
- It is possible to measure the size of round billets.
- Internal measurements with a caliper are much more accurate than the data of all other measuring instruments.
- The depth of the hole or groove is very easy to measure using the depth gauge available in the caliper. It is pushed out of the housing and measured.
- The ledges are also not difficult to measure with high accuracy using a combination of jaws of the device.
Narrow calipers
In addition to universal calipers, there are many special, narrow-profile devices.
For example, a fine adjustment device can be added to a simple vernier caliper. This significantly improves the accuracy of measurements. The presence of a tuning screw indicates a higher class of the device.
There are calipers with a longer depth gauge and a different shape of sponges.
In most cases, for homework and use in private workshops, it is enough to have a universal caliper.