45
③
Turn around the instrument by 90°again. Repeat the
process in ○1 and ○2 until the bubble remains centered (leveled)
at all sites.
4.2.2 Using centering device to centre
1) Set up the tripod
①
Open the tripod. Make sure that the three feet of the
tripod are approximately equal in distance from the center and
that the top is leveled. Screw up the three locking screw.
②
Make sure that the center of the tripod top is right
above the station.
③
Stamp one foot on the ground with your feet.
2) Install the instrument gently on the top of the tripod and
screw up the screw connection. Open the laser plumb through
) key to aim at the station precisely.
3)Using circular level to level the instrument coarsely
4)Using tubular level to level the instrument precisely
5) Precise centering and leveling