NA720/NA724/NA728/NA730-1.0.1en
Checking and adjusting
21
Checking and adjusting of the line-of-sight
With the circular bubble centred
and adjusted, the line of sight
should be horizontal.
Checking (see example):
1. Choose a distance of appr.
30 m within a gentle terrain.
2. Set up a staff at both final
points (A, B).
3. Set up the instrument at point
I
1
(halfway between A and B,
just pass it down) and centre
the bubble.
4. Read both staffs.
reading on A
= 1.832 m
reading on B
= 1.616 m
∆
H = A - B
= 0.216 m
5. Set up the level about 1 m
from staff A
6. Read staff A (eg.: 1.604 m)
7. Find nominal reading B;
eg.: Reading A -
∆
H =
1.604 m - 0.216 m = 1.388 m
8. Read staff B, compare
nominal-/actual- reading.
When the difference
nominal-/actual- reading
is more than 3 mm the line of
sight must be adjusted.
1. Turn the allen key until the
middle hair gives the required
reading (eg. 1.388 m).
2. Check line of sight again.
NA-33
NA-38
NA-34
I
1
B
A
H=1.832
H=1.616
B
A
I
2
d
d
∆
H
∆
H
δ
δ
δ
actual =1.604
nominal
=1.388
