Bosch GPL 3 Professional Original Instructions Manual page 11

OBJ_BUCH-807-005.book Page 11 Wednesday, February 10, 2016 4:07 PM
If the automatic levelling function is not possible, e.g. be-
cause the surface on which the measuring tool stands devi-
ates by more than 5° or 3° from the horizontal plane, the laser
beams flash rapidly. In this case, bring the measuring tool to
the level position and wait for the self-levelling to take place.
As soon as the measuring tool is within the self-levelling range
of ±5° or ±3° respectively, all laser beams light up continu-
ously again.
In case of ground vibrations or position changes during oper-
ation, the measuring tool is automatically levelled in again. To
avoid errors by moving the measuring tool, check the position
of the laser beams with regard to the reference points upon
re-levelling.
Levelling Accuracy
Influences on Accuracy
The ambient temperature has the greatest influence. Espe-
cially temperature differences occurring from the ground up-
ward can divert the laser beam.
As thermal fluctuation is largest close to the ground, the
measuring tool, if possible, should be mounted on a commer-
cially available tripod and placed in the centre of the working
area.
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 be-
ginning work.
Should the measuring tool exceed the maximum deviation
during one of the tests, please have it repaired by a Bosch af-
ter-sales service.
Checking the Horizontal Levelling Accuracy
A free measuring distance of 20 m on a firm surface between
two walls A and B is required for the check.
– Mount the measuring tool onto the holder or a tripod, or
place it on a firm and level surface close to wall A. Switch
the measuring tool on.
A
20 m
– Direct the horizontal laser beam against the close wall A
and allow the measuring tool to level in. Mark the centre of
the laser beam on the wall (point I).
Bosch Power Tools
A
180˚
– Turn the measuring tool around by 180°, allow it to level in
and mark the centre point of the laser beam on the oppo-
site wall B (point II).
Without turning the measuring tool, position it close to wall B.
Switch the measuring tool on and allow it to level in.
A
– Align the height of the measuring tool (using the tripod or
by underlaying, if required) in such a manner that the cen-
tre point of the laser beam is projected exactly against the
previously marked point II on wall B.
A
d
B
– Rotate the measuring tool by 180° without changing the
height. Allow it to level in and mark the centre point of the
laser beam on wall A (point III). Take care that point III is
as vertical as possible above or below point I.
– The difference d of both marked points I and III on wall A
indicates the actual height deviation of the measuring tool.
On the measuring distance of 2 x 20 m = 40 m, the maximum
allowable deviation is: 40 m x ±0,3 mm/m = ±12 mm.
Thus, the difference d between points I and III may not ex-
ceed 12 mm (max.).
Checking the Vertical Levelling Accuracy
For this check, a free measuring distance of approx. 5 m be-
tween floor and ceiling on a firm surface is required.
– Draw a straight line on the ceiling.
English | 11
B
B
B
180˚
1 609 92A 261 | (10.2.16)