Measuring tool knowledge: principle and use of spiral micrometer

April 26, 2021

Principle and use of spiral micrometer

The spiral micrometer is made according to the principle of spiral amplification, that is, the screw rotates in the nut for one week, and the screw advances or retreats by a pitch distance along the rotation axis. Therefore, a small distance moving in the direction of the axis can be expressed by the reading on the circumference. The precision thread of the spiral micrometer has a pitch of 0.5mm, the movable scale has 50 equal division scales, and the movable scale rotates one revolution. The micrometer screw can advance or retreat by 0.5mm, so each small index is rotated, which is equivalent to measuring The micro screw advances or pushes back 0.5/50 = 0.01 mm. It can be seen that each small scale of the movable scale represents 0.01mm, so the spiral micrometer can be accurate to 0.01mm. Since it can be re-estimated, it can be read into the millimeter of millimeters, so it is also known as the micrometer.

When measuring, when the small anvil and the micrometer screw are close together, if the zero point of the movable scale coincides with the zero point of the fixed scale, the micrometer screw is screwed out, and the surface of the small anvil and the micrometer screw just touch the two lengths to be tested. End, pay attention to the forceless rotation or the measurement is not accurate. When you touch the measuring surface, slowly rotate the small knobs on the left and right sides until the sound of the sound is heard. Then the distance that the micro screw moves to the right is the measured length. The entire millimeter of this distance is read on a fixed scale and the fractional part is read by a movable scale.

Tag: Helical Micrometer Screw Measuring Tool Scale Pitch

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