Operating Modes; Automatic Levelling; Accuracy Check Of The Measuring Tool - Bosch GCL 25 Professional Manual Original

14 | English
To deactivate the automatic shut-off function, hold down the
laser mode button (2) for at least 3 s (with the measuring
tool switched on). If the automatic shut-off function is deac-
tivated, the laser beams will flash briefly as confirmation.
To activate the automatic shut-off function, switch the meas-
uring tool off and on again.

Operating Modes

The measuring tool has several operating modes, which you
can switch between at any time:
– Cross-line and point mode: The measuring tool generates
one horizontal and one vertical laser line pointing for-
wards, two vertical point beams (one pointing upwards
and one downwards), and three horizontal point beams
(one pointing forwards and one to either side).
– Five-point mode: The measuring tool generates two ver-
tical point beams (one pointing upwards and one down-
wards), and three horizontal point beams (one pointing
forwards and one to either side).
– Horizontal line mode: The measuring tool generates a ho-
rizontal laser line pointing forwards.
– Vertical line mode: The measuring tool generates a ver-
tical laser line pointing forwards.
All point beams run at a 90° angle to each other and the laser
lines intersect at a 90° angle.
Once switched on, the measuring tool is in the cross-line and
point mode. To change the operating mode, press the laser
mode button (2).
All operating modes can be selected with both automatic lev-
elling or the pendulum lock.

Automatic Levelling

Working with automatic levelling (see figures A–C)
Position the measuring tool on a level, firm surface or attach
it to the universal holder (14) or the tripod (15).
For work with automatic levelling, slide the on/off switch (4)
to the " On" position.
The automatic levelling function automatically levels irregu-
larities within the self-levelling range of ±4°. The levelling is
finished as soon as the laser points and/or laser lines do not
move any more.
If automatic levelling is not possible, e.g. because the sur-
face on which the measuring tool stands deviates by more
than 4° from the horizontal plane, the laser beams begin to
flash. This alarm is deactivated within 10 s after switching
on, in order to allow the measuring tool to be adjusted.
Place the measuring tool in a horizontal position and wait for
self-levelling to take place. As soon as the measuring tool is
within the self-levelling range of ±4°, the laser beams will
light up continuously.
In case of ground vibrations or position changes during oper-
ation, the measuring tool is automatically levelled again.
Upon levelling, check the position of the laser beams with re-
gard to the reference points to avoid errors arising from a
change in the measuring tool's position.
1 609 92A 7SD | (25.07.2022)
Working with a pendulum lock (see figure D)
For work with the pendulum lock, slide the on/off switch (4)
to the " On" position. The laser beams flash continuously.
For work with the pendulum lock, automatic levelling is
switched off. You can hold the measuring tool freely in your
hand or place it on a sloping surface. This means that the
laser beams are no longer levelled and no longer necessarily
run perpendicular to one another.

Accuracy Check of the Measuring Tool

Influences on Accuracy
The largest influence is exerted by the ambient temperature.
In particular, temperature differences that occur from the
ground upwards can refract the laser beam.
In order to minimise thermal influences resulting from heat
rising from the floor, it is recommended that you use the
measuring tool on a tripod. In addition, position the measur-
ing tool in the centre of the work surface, wherever this is
possible.
In addition to external influences, device-specific influences
(e.g. falls or heavy impacts) can also lead to deviations. For
this reason, check the levelling accuracy each time before
beginning work.
If the accuracy of the horizontal point beams is within the
maximum permitted deviation, this means the accuracy of
the vertical point beams and the laser lines has also been
verified.
Should the measuring tool exceed the maximum deviation
during one of the tests, please have it repaired by a Bosch
after-sales service.
Checking the horizontal levelling accuracy of the
longitudinal axis
For this check, you will need a free measuring distance of
20 m on firm ground between two walls (designated A
and B).
– Mount the measuring tool close to wall A on the holder
(14) or a tripod, or place it on a firm, level surface.
Switch on the measuring tool and select five-point mode
with automatic levelling.
A
20 m
– Aim the horizontal laser beam that runs parallel to the lon-
gitudinal axis of the measuring tool at the closer wall A
and allow the measuring tool to level in. Mark the centre
of the laser point on the wall (point Ⅰ).
B
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