Use method:
after loosening the screws, pull the hen the "0" line on the cursor is aligned with the "0" line on the main scale, it means that the measuring surface A is parallel to the datum level and the datum level, B is perpendicular to the datum level.
1) when the cursor "0" the right of the line in the main dial "0" line, degree, with cursor "0" read scores with the right of the cursor "0" line scale reading (reading the same as the vernier caliper) read out the degrees (°), A and B measurement plane counterclockwise (') said the turning Angle.
When the cursor "0" line in the main scale "0" line left, the degree is still read with the cursor "0" line, the score with the cursor "0" line left scale read. Read out the degrees (°), the (')
A and B measure the clockwise rotation Angle of the surface.
(3) adjust the Angle to the target value and tighten the rench