(A) Align the plate vial in parallel with a line joining any two of the levelling screws.
Then, adjust the two screws to centre the bubble in the plate vial.
- Turn two levelling screws in an opposite direction mutually in a way that the bubble moves from the side of the plate vial to the centre.
(B) Rotate the total station 90°.
- Use the remaining screw to centre the bubble in the plate vial.
- Rotate the instrument by 90° and 180° and confirm the position of the bubble in the plate vial. At this time, it is not necessary to adjust it if the bubble of the plate vial is in the vicinity of the centre.