Accuracy Check Of The Measuring Tool; Working Advice - Bosch GRL 250 HV Professional Originalbetriebsanleitung

Now check the position of the laser beam at a reference
point and, if necessary, correct the height or alignment of
the measuring tool.
When, after the shock-warning function has actuated, the
function is not restarted by pressing the shock-warning
button (2) on the measuring tool or the shock-warning reset
button (22) on the remote control, the laser is automatically
switched off after 2 minutes and the measuring tool after
2 hours.
Switching off the shock-warning function: Press the
shock-warning button (2) once or, when the shock warning
has actuated (shock-warning indicator (1) flashing red),
press it twice. When the shock-warning function is switched
off, the shock-warning indicator goes out.
Note: The shock-warning function cannot be switched on or
off with the remote control; it can only be restarted after
having actuated.

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-
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.
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 Levelling Accuracy in a Horizontal Position
For a reliable and precise result, it is recommended that you
check the levelling accuracy on a free measuring distance
of 30 m on firm ground in front of a wall. Carry out a com-
plete measuring procedure for each of the two axes.
– Mount the measuring tool in a horizontal position 30 m
from the wall on a tripod, or place it on a firm, level sur-
face. Switch on the measuring tool.
30 m
– Once levelling is complete, mark the centre of the laser
beam on the wall (point Ⅰ).
Bosch Power Tools
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– Rotate the measuring tool 180° without changing its posi-
tion. Allow it to level in and mark the centre point of the
laser beam on the wall (point Ⅱ). Note that point Ⅱ should
preferably be positioned vertically above or below point Ⅰ.
The discrepancy d between the two marked points Ⅰ and Ⅱ
on the wall reveals the actual height deviation of the measur-
ing tool for the axis being measured.
Repeat the measuring process for the other axis. To do this,
turn the measuring tool by 90° before beginning the meas-
urement.
The maximum permitted deviation on the 30 m measuring
distance is as follows:
30 m × ±0.1 mm/m = ±3 mm. The discrepancy d between
points Ⅰ and Ⅱ must therefore amount to no more than 6 mm
for each of the two measuring processes.

Working Advice

Only the centre of the laser point or laser line must be
u
used for marking. The size of the laser point/the width of
the laser line changes depending on the distance.
Working with the Laser Target Plate (see figure C)
The laser target plate (41) improves visibility of the laser
beam in unfavourable conditions and at greater distances.
The reflective surface of the laser target plate (41) improves
visibility of the laser line. The transparent surface enables
the laser line to be seen from behind the laser target plate.
Working with the Tripod (Accessory)
A tripod offers a stable, height-adjustable support surface
for measuring. Place the measuring tool with the 5/8" tripod
mount (15) on the thread of the tripod (32). Tighten the
measuring tool using the locking screw of the tripod.
On a tripod featuring a measuring scale on its extender, you
can set the height deviation straight away.
Roughly align the tripod before switching on the measuring
tool.
Working with the WM 4 wall mount (accessory)
(see figure D)
You can also mount the measuring tool on the wall mount
with the alignment unit (36). For this, screw the 5/8"
screw (38) of the wall mount into the tripod mount (15) of
the measuring tool.
Mounting on a wall: Wall-mounting is advisable, for ex-
ample for work performed above the maximum extension
height of tripods, or for work on unstable surfaces and
without tripods.
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1 609 92A 7AR | (07.02.2022)