1. Observe the eyepiece. There is a scale in the lens. Rotate the drum on one side of the reading microscope to align the vertical line in the lens with the zero scale line on the scale.
2. Place the zeroed reading microscope above the indentation to be measured and ensure that the indentation is located in the center of the microscope field of view.
3. Move the microscope so that the vertical line is tangent to the right edge of the indentation. Press and hold the bottom of the reading microscope, turn the drum and move the vertical line so that the vertical line is tangent to the right edge of the indentation.
4. Read the integral part (unit: mm) of the indentation diameter from the scale center on the horizontal line, and then read the decimal part (two digits, accurate to 0.01mm) of the indentation diameter from the drum on one side of the reading microscope.
5. Rotate the indentation 90 ° and measure it again (because the indentation is usually irregular, rotate the workpiece 90 ° and measure it again to take the average value). Take the average value of the two results to obtain the diameter of the indentation, which will be more accurate.
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