Micrometer - a very high precision instrument for measuring the size of parts. It is used where there is a need for scrupulous compliance with the dimensions in the manufacture of products. The accuracy of its measurements is one thousandth of a millimeter (micrometer or micron), and the error is only 2 to 50 microns. This is much more accurate than that of the same calipers. To imagine such quantities more clearly, it should be recalled that the thickness of a human hair is about 40 microns, and the erythrocyte diameter is 7 microns.
The principle of the micrometer
The movable focus of the device is a micrometer screw. A stopper is used to clamp it in the desired position. A drum is placed on the stem, which is a conical surface, divided by strokes into 50 equal parts and put on the stem. One revolution of the micrometer screw, and consequently of the drum, leads to displacement along its axis by 0.5 mm. Thus, one turn of the drum per division is 1/50 of 0.5 mm or 0.01 mm. To avoid deformation of the part, a ratchet is used to limit the pressure on the micrometer screw.
How to use a micrometer when performing measurements
A detail, the dimensions of which need to be measured, is placed between the heel and the micrometer screw. Rotating the drum, set the spindle as close to the part as possible.
- Carefully slide the spindle until it touches the part to be measured. Twisting should be done only by holding on to the thread placed on the end of the rotating drum. When the measuring face rests against the part, the scrolling part of the drum will sound (click) on the way. After the third click, the rotation should be stopped.
- Using a vernier measure the parts in millimeters, which is read by a horizontal index stroke located on the stem scale.
- Determine the overall dimensions of the measured part.
- Release the part by rotating the drum in the reverse direction.
At the conclusion of the article on how to use a micrometer, it should be noted that using this simple but reliable instrument is not difficult, and the ability to determine the exact dimensions of particularly small parts can sometimes be very useful.