The maximum permitted deviation over the mea-
suring distance of 2 × 16 ft = 32 ft (2 × 5 m = 10
m) is as follows:
GLL50-20: 32 ft x ±0.0098 in/ft = ±5/16 in (0.312
in) (10 m × ±0.8 mm/m = ±8 mm). The discrep-
ancy d between points I and III must therefore
amount to no more than 8 mm.
GLL50-20G: 32 ft x ±0.0078 in/ft = ±1/4 in (0.25
in) (10 m × ±0.7 mm/m = ±7 mm). The discrep-
ancy d between points I and III must therefore
amount to no more than 7 mm.
Checking the Level Accuracy of the
Horizontal Line
For this check, you will need a free area of 16 ×
16 ft (5 × 5 m).
— Mount the measuring tool in the middle be-
tween walls A and B on a tripod , or place it
on a firm, level surface. Turn the measuring
tool on the magnetic rotating mount 4 so that
the laser outlet aperture 2 is not obstructed.
Switch the measuring tool on and allow it to
level in.
— At a distance of 8 ft (2.5 m) from the measur-
ing tool, mark the center of the laser line on
both walls (point I on wall A and point II on
wall B).
A
— Set up the measuring tool at a 5 m distance
and rotated by 180° and allow it to level in.
A
14
160992A8JG GLL50-20 G 202306.indd 14
Operation
B
B
— Align the height of the measuring tool (using
the tripod or by placing objects underneath
as required) so that the center of the laser
line exactly hits the previously marked point
II on wall B.
— Mark the center of the laser line on wall A as
point III (vertically above or below point I).
— The discrepancy d between the two marked
points I and III on wall A reveals the actual
horizontal deviation of the measuring tool.
The maximum permitted deviation over the mea-
suring distance of 2 × 16 ft = 32 ft (2 × 5 m = 10
m) is as follows:
GLL50-20: 32 ft x ±0.0098 in/ft = ±5/16 in (0.312
in) (10 m × ±0.8 mm/m = ±8 mm). The discrep-
ancy d between points I and III must therefore
amount to no more than 8 mm.
GLL50-20G: 32 ft x ±0.0078 in/ft = ±1/4 in (0.25
in) (10 m × ±0.7 mm/m = ±7 mm). The discrep-
ancy d between points I and III must therefore
amount to no more than 7 mm.
Checking the Level Accuracy of the
Vertical Line
For this check, you will need a door opening (on
solid ground) which has at least 8 ft (2.5 m) of
space either side of the door.
— Place the measuring tool 8 ft (2.5 m) away
from the door opening on a firm, flat surface
(not on a tripod). Turn the measuring tool on
the magnetic rotating mount 4 so that the la-
ser outlet aperture 2 is not obstructed. Switch
the measuring tool on and allow it to level in.
— Mark the center of the vertical laser line on
the floor of the door opening (point I), 16 ft (5
m) away on the other side of the door opening
(point II) and on the upper edge of the door
opening (point III).
6/9/23 9:46 AM