Bosch GLL 50 Operating/Safety Instructions Manual page 22

In addition to external influences, device-specific influences (e.g. falls
or heavy impacts) can also lead to deviations. For this reason, check
the leveling accuracy each time before beginning work.
First, check both the height as well as the leveling accuracy of the hori-
zontal laser line, then the leveling accuracy of the vertical laser line.
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 Height Accuracy of the Horizontal Line
For this check, a free measuring distance of 16 ft (5 m) on a firm sur-
face between two walls A and B is required.
– Mount the measuring tool onto a tripod or place it on a firm and level
surface close to wall A. Switch on the measuring tool. Select cross-
line operation with automatic leveling.
– Direct the laser against the close wall A and allow the measuring
tool to level in. Mark the center of the point where the laser lines cross
each other on the wall (point I).
A
B
16 ft (5 m)
– Turn the measuring tool by 180°, allow it to level in and mark the
cross point of the laser lines on the opposite wall B (point II).
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