Bosch GRL 400 H Professional Manual Original página 22

OBJ_BUCH-1179-006.book Page 22 Wednesday, February 1, 2017 10:13 AM
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).
– Without turning the measuring tool, position it close to
wall B. Switch the measuring tool on and allow it to level in.
1 609 92A 1XU | (1.2.17)
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
– Rotate the measuring tool by 180° without changing the
height. Allow it to level in and mark the centre point of the
B
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
maximum 6. 4 mm in each of the four measuring procedures.
B
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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