David White 4200H - ACCURACY CHECK; Checking the Leveling Accuracy

-13-
ACCURACY CHECK
The ambient temperature has
the greatest influence. Especially
temperature differences occurring
from the ground upward can divert
the laser beam. The deviations play a
role in excess of approx. 65-ft (20m)
measuring distance and can easily
reach two to four times the deviation
at 330-ft (100m). Because the largest
difference in temperature layers is
close to the ground, the instrument
should always be mounted on a
tripod when measuring distances
exceeding 65-ft (20m). If possible,
also set up the instrument in the
center of the work area.
Checking the Leveling Accuracy
Apart from exterior influences,
device-specific influences (such as
heavy impact or falling down) can
lead to deviations. Therefore, check
the accuracy of the instrument each
time before starting your work. A
free measuring distance of 165-ft
(50m) on a firm surface is required for
the check. A reversal measurement
must be carried out over both axes X
and Y (each positive and negative; 4
complete measurements).
– Mount the instrument in the
horizontal position onto a tripod or
place it on a firm and level surface
near wall. Switch the instrument
on. Position the X-axis to aim to a
wall or target plate.
165-ft (50 m)
H1
Y1
165-ft (50 m)
H1
H2
Y2
100-ft (30 m)
1.5-ft
(0.5 m)
A
H1
B
100-ft (30 m)
1.5-ft
(0.5 m)
A
H1
H2
B
100-ft (30 m)
1.5-ft
(0.5 m)
A
H1
D
H3
H2
B
100-ft (30 m)
1.5-ft
(0.5 m)
A
H1
H2
B
D
180°
165-ft (50 m)
H1
X1
165-ft (50 m)
H1
H2
X2
D
180°
180°
180°
180°
10°
45°
90°
RPM
4250HV
– After the leveling, mark the center of
the laser beam on wall (point H1).
– Rotate the instrument by 180°,
allow it to level in and mark the
center point of the laser beam on
the wall (point H2).
165-ft (50 m)
H1
Y1
165-ft (50 m)
H1
H2
Y2
100-ft (30 m)
1.5-ft
(0.5 m)
A
H1
B
100-ft (30 m)
1.5-ft
(0.5 m)
A
H1
H2
B
100-ft (30 m)
1.5-ft
(0.5 m)
A
H1
D
H3
H2
B
100-ft (30 m)
1.5-ft
(0.5 m)
A
H1
H2
B
D
180°
165-ft (50 m)
H1
X1
165-ft (50 m)
H1
H2
X2
D
180°
180°
180°
180°
10°
45°
90°
RPM
4250HV
– The difference D of both marked
points H1 and H2 on wall is the
actual deviation of the instrument
for the measured axis.
The value of D (deviation) should be
less than 5/16-in (8mm).