Ironside Prolaser 3D All-Lines Mode D'emploi page 22

5) Rotate the laser 90° counterclockwise so that the cross beams
pass through c1 on the table, and the forward laser beam passes
through the marks a1 and b1 on the walls A and B respectively.
6) Mark as c3 the center of the side vertical beam on wall C, at the
same height as point c2. (see figure # 8 ).
22
102494