Bosch Professional GLL 3-50 Original Instructions Manual page 16

16 | English
Receiver Mode
Receiver mode must be activated when working with the
laser receiver (23), regardless of which operating mode is
selected.
In receiver mode, the laser lines flash at a very high fre-
quency, enabling them to be detected by the laser receiver
(23).
To switch on receiver mode, press the receiver mode button
(3). The receiver mode indicator (2) will light up green.
When receiver mode is switched on, the laser lines are less
visible to the human eye. Therefore, switch receiver mode
off by pressing the receiver mode button (3) again to work
without a laser receiver. The receiver mode indicator (2) will
go out.
Automatic Levelling
Working with Automatic Levelling
Position the measuring tool on a level, firm surface or attach
it to the rotating platform (16) or the tripod (21).
For work with automatic levelling, slide the on/off
switch (12) 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 beams stop flashing.
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 will begin
to flash quickly.
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 re-levelling, check the position of the horizontal or ver-
tical laser line with regard to the reference points to avoid er-
rors by moving the measuring tool.
Working with the pendulum lock
For work with the pendulum lock, slide the on/off
switch (12) to the " On" position. The laser lines continu-
ously flash slowly when working with the pendulum lock.
For work with the pendulum lock, the 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 lines 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-
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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.
First check the height accuracy and levelling accuracy of the
horizontal laser line, then the levelling accuracy of the ver-
tical laser line.
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 Height Accuracy of the Horizontal Line
For this check, you will need a free measuring distance of
5 m on firm ground between two walls (designated A and B).
– Mount the measuring tool close to wall A on a tripod, or
place it on a firm, level surface. Switch on the measuring
tool. Select cross-line mode with automatic levelling.
A
5 m
– Aim the laser at the closer wall A and allow the measuring
tool to level in. Mark the middle of the point at which the
laser lines cross on the wall (point I).
A
180°
– Turn the measuring tool 180°, allow it to level in and mark
the point where the laser lines cross on the opposite wall
B (point Ⅱ).
– Position the measuring tool – without rotating it – close to
wall B, switch it on and allow it to level in.
B
B
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