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Checking the Leveling Accuracy in the
Horizontal Position
An unobstructed area of 100 ft (30 m) on a
firm surface in front of a wall is required for the
check. A complete accuracy check must be
carried out for the X- and Y-axis.
– Mount the laser tool in the horizontal position
onto a tripod or place it on a firm and level
surface at a distance of 100 ft (30 m) to the
wall. Switch the laser tool on.
– After the leveling, mark the center of the laser
beam on the wall (point
I
).
– Rotate the laser tool by 180°, allow it to level
in and mark the center point of the laser
beam on the wall (point
II
). Make sure that
point
II
is as vertical as possible above or
below point
I
.
– The difference d of both marked points
I
and
II
on the wall results in the actual
height deviation of the laser tool for the
measured axis.
Repeat the procedure for the other axis. For
this, turn the laser tool by 90° before starting.
The maximum permitted deviation over the
recommended distance of 100 ft (30 m) is as
follows:
For GRL800-20HV:
100 ft x ±3/16 in = ±3/16 in
(30 m x ±0.15 mm = ±4.5 mm)
For GRL900-20HV and GRL1000-20HV:
100 ft x ±1/8 in = ±1/8 in
(30 m x ±0.10 mm = ±3.0 mm)
The difference d between points I and II
must therefore be maximum 3/8 in (9mm) for
GRL800-20HV and ¼ in (6 mm) for GRL900-
20HV and GRL1000-20HV in each of the two
accuracy check procedures.
Checking the Leveling Accuracy in the
Vertical Position
An unobstructed area of 30 ft (10 m) on a firm
surface in front of a wall is required for the
check. Fasten a plumb bob rope to the wall.
– Mount the laser tool in the vertical position
onto a tripod, or place it on a firm and level
surface. Switch the laser tool on and allow it
to level.
– Align the laser tool such that the laser
beam impinges centrally on the plumb bob
rope at the upper end. The difference d
between laser beam and plumb bob rope
at the bottom end of the rope results in the
deviation of the laser tool to the vertical line.
The maximum permitted deviation over a 30 ft
(10 m) distance is as follows:
For GRL800-20HV:
30 ft x ±3/16 in = ±1/16 in
(10 m x ±0.15 mm = ±1.5 mm)
For GRL900-20HV and GRL1000-20HV:
30 ft x ±1/8 in = ±3/64 in
(10 m x ±0.1 mm = ±1 mm)
The difference d must therefore be a maximum
of 1/16 in (1.5 mm) for GRL800-20HV and 3/64
in (1 mm) for GRL900-20HV and GRL1000-
20HV.
GRL800_900_1000 10-18.indd 16
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