Bosch GRL 400 H Professional Notice Originale page 22

OBJ_BUCH-1179-004.book Page 22 Monday, December 7, 2015 5:49 PM
22 | English
Levelling Accuracy of the Rotational Laser Level
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.
The deviations play a role in excess of approx. 20 m measur-
ing distance and can easily reach two to four times the devia-
tion at 100 m.
Because the largest difference in temperature layers is close
to the ground, the measuring tool should always be mounted
on a tripod when measuring distances exceeding 20 m. If pos-
sible, also set up the measuring tool in the centre of the work
area.
Accuracy Check of the Measuring Tool
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.
A free measuring distance of 20 m on a firm surface between
two walls A and B is required for the check. A reversal meas-
urement must be carried out over both axes X and Y (each
positive and negative; 4 complete measurements).
– Mount the measuring tool onto a tripod, or place it on a firm
and level surface close to wall A. Switch the measuring tool
on.
A
20 m
– After the levelling, mark the centre of the laser beam on
wall A (point I).
A
180°
– Rotate the measuring tool by 180°, allow it to level in and
mark the centre point of the laser beam on the opposing
wall B (point II).
1 609 92A 264 | (7.12.15)
– 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 propping), so that the centre of the laser beam runs ex-
actly against the previously marked point II on wall B.
A
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
amounts to the actual deviation of the measuring tool for the
measured axis.
– Repeat the measuring procedure for the other three axes.
For this, turn the measuring tool prior to each measuring
procedure by 90°.
The maximum permitted deviation over the measuring sec-
tion of 2 x 20 m = 40 m is as follows:
40 m x ±0.08 mm/m = ±3,2 mm.
The difference d between points I and III must therefore be
B
maximum 6,4 mm in each of the four measuring procedures.
If the measuring tool should exceed the maximum deviation in
any one of the four measuring procedures, have it checked at
a Bosch after-sales service agent.
B
B
180°
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