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Checking the calibration
The LA-4P four-point laser has been designed for building site use and leaves our
factory perfectly calibrated. As with any precision instrument, however, its calibra-
tion must be regularly checked. The unit should be checked before starting any
new tasks, particularly when the unit has been exposed to strong vibrations. After
an impact, the unit should be checked throughout its whole self-levelling range.
Checking plumb
1.
Switch the unit on ( button 1)
1
Place the laser so that its down beam
2.
is over a reference mark on the floor.
Locate the position of the up beam
3.
on the ceiling and make a mark.
4.
Rotate the laser 180° and realign the
down beam over the reference mark
on the floor.
5.
Locate the position of the up beam on
the ceiling, which will be twice the
actual error, and make a mark.
6.
Measure the difference between the two
marks on the ceiling, which will be twice
the actual error.
The difference may not be greater than:
3/16" in 25 ft (6mm in 7.5 m),
< 6mm
< 3 /16"
7,5m / 25 ft
4
Checking level
Two parallel wall surfaces at least 20 ft ( or 6m) apart are required for the
horizontal check.
Set the four-point laser on a flat surface, or mount it on a tripod, at a distance
1.
of 2" to 3" ( 50 to 75mm) from a wall A, with its front sidefacing the wall.
2.
Switch the unit on ( button 1)
3.
Mark the position of the visible laser dot on the wall (point 1)
4.
Turn the complete unit 180° without altering the height of the laser.
5.
Mark the position of the visible laser dot on the wall (point 2).
6.
Now move the unit directly in front of wall B
7.
Set the unit's height so that the laser dot's height matches that of point 2.
8.
Without changing the height of the laser, rotate it 180° to place the beam near
the mark on the first wall (step 3 / point 1 ).
Measure the vertical distance between the
beam and the mark made in step 3.
The difference may not be greater than:
S
Measured Value
20 ft
/ 6m
1/8 inch
3.0 mm
40 ft
/12m
1/4 inch
6.0 mm
60 ft
/18m
5/16 inch
8.0 mm
80 ft
/24m
7/16 inch
11.0 mm
5
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