14) Mark point a2 on the wall A, in the middle of the side vertical
beam, near the point a1, and at the same height.
(see figure #13).
X
d1
15) Measure the distances:
16) The difference Δ from a1 to a2 should not be more than 3 mm,
otherwise, send the laser level to a qualified technician for
repairs.
17) Repeat the same procedure (1 – 16) to check the perpendicularity
between the other 2 vertical beams.
D
Figure # 13
Figure # 13
Δ = from a1 to a2
A
a1 X a2
X
X
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