– Turn the measuring tool by 180°. Position it so that the centre
of the bottom laser point falls onto the marked point II. Allow
the measuring tool to level in. Mark the centre of the top laser
point (point III).
– The discrepancy d between the two marked points I and III on
the ceiling reveals the actual deviation of the measuring tool
from the vertical plane.
You can calculate the maximum permitted deviation as follows:
Doubled distance between floor and ceiling × 0.0084 in/ft (0.7
mm/m)
Example: At a floor-to-ceiling distance of 8 ft (2.5 m), the maxi-
mum deviation amounts to
2 × 8 ft x 0.0084 in/ft = 0.25"
(2 × 2.5 m × ±0.3 mm/m = ±1.5 mm)
The points I and III must therefore be no further than .25" (1.5
mm) from each other.
GPL100-30G 50G 11-20.indd 23
d
180°
-23-
4/23/21 5:27 PM