©2012 Johnson Level & Tool
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8. Self-Check & Fine Calibration
IMPORTANT:
It is the responsibility of the user to verify the
calibration of the instrument before each use.
Horizontal line accuracy (horizontal)
1. Place unit on a tripod approximately 5m from a wall. Secure the
instrument on the tripod.
2. Face the front of the instrument to the wall, unlock the
instrument, and power on the horizontal and vertical laser lines.
Make a mark on the wall where the cross-line is displayed. Label
this as ‘A’.
3. Make a mark 2.5m from A, along the horizontal laser line, and
label as ‘M’.
4. Turn the instrument until the vertical line meets ‘M’, and then
make a mark 2.5m from ‘M’, and 5m from ‘A’. Label this mark as
‘B’. Also make a mark on the vertical line where it meets ‘B’.
5. Measure the height distance between ‘M’ and where the
horizontal laser line currently sits.
6. If e>1mm, the instrument accuracy is out of tolerance, and cali-
bration is necessary.
Horizontal accuracy self-check (Vertical)
1. Stand up two straight poles/boards 5m from each other, or two
walls which are parallel and more than 5m distance.
2. Place the instrument on the tripod, and place in the center of
the poles/boards/walls, and level the instrument by adjusting
the tripod.
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