Bosch BL 130I PROFESSIONAL Instructions D'emploi page 18

bl130i_bu_1609929F17_t.fm Seite 5 Montag, 21. April 2008 4:22 16
Levelling Accuracy
Influences on the Accuracy
The largest influence is exerted by the ambient tem-
perature. Especially temperature differences occurring
from the ground upwards can deflect the laser beam.
The deviations are significant at a distance of approx.
20 m and can double or quadruple at a distance of
100 m.
Since the temperature gradient near the floor is the
greatest, a tripod should always be used when work-
ing at distances over 20 m. In addition, the unit
should always be set up in the middle of the working
area.
Accuracy Check of the Unit
In addition to external influences, specific unit influenc-
es can also lead to deviations. Therefore, check the
accuracy of the unit each time before beginning work.
For this purpose, a unobstructed measuring path of
20 m on firm ground between two walls A and B is
necessary. A transit measurement in the horizontal po-
sition over both X and Y axes (each positive and neg-
ative) must be performed (four complete measurement
procedures).
– Place the unit in the horizontal position on a firm,
level base or on a tripod (accessory) near the wall
A and switch on.
– After the levelling, aim the laser beam in point op-
eration at the near wall A. Mark the middle point of
the laser beam on the wall (I).
– Turn the unit by 180°, let it level and mark the mid-
dle point of the laser beam on the distant wall B
(II).
1 609 929 F17 • (04.05) T
– Place the unit – without turning it – near the wall B,
switch on and allow to level.
– Adjust the unit in height (with the aid of the tripod
or by placing an object underneath) so that the
middle point of the laser beam is exactly at the
previously marked point II on the wall B.
– Turn the unit by 180° without changing the height,
allow to level and mark the middle point of the la-
ser beam on the wall A (III).
– The difference d between the two marked points I
and III on the wall A gives the actual unit deviation
for the measured axis.
Repeat the measurement procedure for the other
three axes. For this purpose, turn the unit by 90° each
time before beginning the measurement procedure.
For the measured distance of 2 x 20 m = 40 m, a de-
viation of ±4 mm is acceptable. Therefore, the highest
and the lowest marks may be 8 mm apart.
Should the unit exceed the maximum deviation for one
of the four measurement procedures, it is to be takes
to the Bosch customer service.
English–5