Sometimes, when working, it may be necessary to accurately determine the size of any part. For this purpose, a universal tool is intended - a micrometer, with which the outer dimension of the part is determined with an accuracy of 2 μm (0.002 mm). Next, consider and give an example of how to use a micrometer.
The device of a mechanical micrometer
There are two types of micrometers: mechanical and electronic.
The device of a mechanical micrometer assumes the presence of the following parts:
- heel - fixed stop;
- micrometric screw;
- Stem stem with threaded bush;
- a drum rigidly fixed on the screw;
- ratchet;
- a ring nut;
- two scales.
The screw rotates in the threaded bush of the stationary stem. With the help of the drum, the screw is unscrewed. It is possible to fix the screw in any position with a ring nut.
Two scales, which are located on the device, are arranged as follows. The first is on the stem and has a division price of 1 mm. This scale is divided into two parts, with the lower part offset from the top by 0.5 mm. This arrangement facilitates the measurement process. On the rotating drum there is a second scale, which has 50 divisions with a price of 0.01 mm.
How to use the micrometer correctly?
Since during use, the scale is knocked down periodically, it is recommended that the instrument be calibrated before each application. It is carried out in the following way: the screw is fully twisted and verified that the horizontal risk on the stem coincides with the zero mark on the drum. In case of mismatch, the stem is twisted with a special key.
In order to use the micrometer for the purpose of measuring the part, the screw is twisted by rotating the drum a distance that will slightly exceed the size of the part. The part to be measured is clamped between the heel and the screw. To prevent damage to the part, it is clamped with a ratchet. In this case, the ratchet generates a distinctive sound when triggered. Then tighten the ring nut.
To determine the size of the part, add together the readings of two scales (two parts of the first scale on the stem and one scale on the drum). On the upper part of the scale of the stem, we look at the number of complete mm. If the risk on the lower part of the scale of the stem is to the right, then to the value of the upper part of the scale it is necessary to add 0.5 mm. To the obtained value, we add the readings from the scale on the drum, with the division price 0.01 mm.
How to use the micrometer correctly - an example of a measurement
Consider an example of an accurate measurement of the drill diameter, whose nominal size is 5.8 mm. The drill is clamped between the fixed stop and the screw using a ratchet. Further, the readings of the device are made.
Look at the top of the scale on the stem. Its value will be 5 mm. We determine the position of the visible risks of the lower part of the stem scale. It will be to the right, so we
Next, look at the scale on the drum, which shows us the value of 0.28 mm. Add these data to the scale of the stem and get 5.5 mm + 0.28 mm = 5.78 mm.
The exact diameter of the drill will be 5.78 mm.
Thus, the device micrometer will help you to measure an object or part with maximum accuracy. If you do not have enough of the sizes that you can get with a ruler or caliper , you have the opportunity to conduct a measurement using a micrometer and obtain dimensions with an accuracy of 0.002 mm.