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To tilt an axis with au-
tomatic levelling
switched off, press
the slope button (14)
while the menu for manual operating mode
is displayed.
If automatic leveling is only switched off for
one axis, it will only be possible to change the
slope of that axis. When manually operating
both axes, it is possible to switch between the
axes by pressing the slope button (14) again.
The symbol for the axis whose slope can be
changed will flash.
Tilt the selected axis using the ▲ (4) or ▼ (3)
buttons until the required position is reached.
Manual operation in the vertical position
(for GRL4000-80CHV only).
To switch off automatic leveling
for the X-axis, press the manual
operation button (13) once. (The
Y-axis cannot be leveled when in
the vertical position.)
To tilt the X-axis without using au-
tomatic leveling, press the slope
button (14) while manual operat-
ing mode is indicated on the dis-
play. The symbol for the X-axis
will flash on the display.
Tilt the X-axis using the ▲ (4) or ▼ (3) buttons
until the required position is reached.
To rotate the Y-axis, press the
slope button (14) again while
manual operating mode menu is
displayed. The symbol for the Y-
axis will flash on the display.
Rotate the Y-axis using the ▲ (4) or ▼ (3) but-
tons until the required position is reached.
Accuracy Check of the
Laser level
The following tasks should be performed only
by well-trained and qualified persons. The le-
galities with regard to performing an accuracy
check or calibration of a laser level must be
known.
Influences on Accuracy
The largest influence is exerted by the ambi-
ent temperature. In particular, temperature
differences that occur from the ground up-
wards can refract the laser beam.
Since the temperature stratification is great-
est at ground level, you should always mount
the laser level on a tripod for measuring dis-
tances of 65.6 ft or more. In addition, posi-
tion the laser level in the center of the work
surface, wherever this is possible.
The deviations have an impact on measuring
distances of approx. 65.6 ft (20 m) or more,
and at 300 ft (100 m) the deviation can easily
be two to four times larger than that at 65.6
ft (20 m).
In addition to external influences, device-spe-
cific influences (e.g. falls or heavy impacts)
can also lead to deviations. For this reason,
check the leveling accuracy each time before
beginning work.
If the laser level exceeds the maximum devia-
tion for the measuring procedures described
below, perform a calibration (see “Calibrat-
ing the laser level”, page 29) or have the laser
level checked by a Bosch customer service
agent.
Checking the leveling accuracy in a horizon-
tal position
For this check, you will need a free measuring
distance of 100 ft on firm ground in front of
a wall. You need to complete the entire mea-
surement process for the X and Y-axis respec-
tively.
– Mount the laser level in a horizontal position
100 ft from the wall on a tripod, or place it
on a firm, level surface. Switch on the laser
level.
100 ft (30 m)
– Once leveling is complete, mark the center
of the laser beam on the wall (point I).
180°
d
