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OBJ_BUCH-847-002.book Page 16 Friday, May 16, 2014 7:10 AM
16 | English
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.
Apart from exterior influences, device-specific influences
(such as heavy impact or falling down) can lead to deviations.
Therefore, check the accuracy of the measuring tool each
time before starting your work.
Should the measuring tool exceed the maximum deviation
during one of the tests, please have it repaired by a Bosch
after-sales service.
When the levelling accuracy of the horizontal laser beams is
within the maximum allowable deviation, then the levelling
accuracy of the crossed laser lines (vertical axis) is thus also
checked.
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 a tripod, or place it on a firm
and level surface close to wall A. Switch the measuring tool
on.
A
20 m
– Direct a horizontal point beam against (the closer) wall A.
Allow the measuring tool to level in. Mark the centre of the
laser beam on the wall (point I).
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.
1 609 92A 0KY | (16.5.14)
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
– 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.
B
– The difference d of both marked points I and III on wall A
results in the actual height deviation of the measuring tool
for the first point beam.
Repeat the measuring procedure for both other point beams.
For this, turn the measuring tool by 90° each time before
starting the measuring procedure.
On the measuring distance of 2 x 20 m = 40 m, the maximum
allowable deviation is: 40 m x ±0.2 mm/m = ±8 mm.
Consequently, the difference d between points I and III for
each of the three individual measurements may not exceed
8 mm.
Working Advice
For marking, always use only the centre of the laser
B
point or the laser line. The size of the laser point as well as
the width of the laser line change with distance.
Working with the Laser Target Plate
The laser target plate 14 increases the visibility of the laser
beam under unfavourable conditions and at large distances.
The reflective part of the laser target plate 14 improves the
visibility of the laser line. Thanks to the transparent part, the
laser line is also visible from the back side of the laser target
plate.
B
B
180˚
Bosch Power Tools
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