1. Look into the ocular and turn the rotational barrel dial to make the vertical lens line aligned with the "0" scale of the horizontal line, meanwhile look at the barrel outside, the long black scale mark should rest on "0" scale of the rotational drum dial.
2. Put the reading microscope on the test piece to locate the indentation in the centre of the viewing field of the microscope. Move the microscope to make the vertical line tangential to the left edge of the indentation. Press the bottom of the reading microscope firmly, turn the rotational drum dial and make the vertical line tangential to the right edge of the indentation.
3. Read the integer part (mm) of the indentation diameter from the horizontal scale mark, then read the 2-digit decimal part of the indentation diameter from the rotational drum, accurate to 0.01mm.
4. In routine use, when you look into the ocular, let the vertical line is aligned with the "0" scale mark of the horizontal line, but in the outside barrel if the "0" scale mark of the rotational drum dial does not align with the long black scale mark, it means the microscope is inaccurate. Adjustment should be made as follow:
a. Make the vertical lens line aligned with the "0" scale mark of the horizontal line.
b. Loosen the three screws on the rotational drum dial.
c. Make the "0" scale mark on rotational drum dial exactly aligned with the long reading mark.
d. Fasten the three screws.
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