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©2009 Johnson Level & Tool
Y-Direction Accuracy Calibration
1. Turn the lock knob to the “OFF’ position.
2. Screw off the Y-direction self-calibration aperture bolt located
behind the handle. Adjust the weight screw inside the instru-
ment core with a flathead screwdriver.
3. If point C is above the point O, rotate the screw-
driver counterclockwise. If point C is under the
point O, rotate the screwdriver clockwise.
Note:
After the unit is checked in one direction, check
the other direction, until the accuracy of the two directions are both
within specification.
Note:
Install the self-calibration aperture screw and rubber stopper
after finishing the accuracy self-check and calibration.
Accuracy Self-check in vertical status
1. Follow the operations as shown above, and measure the distance
“H1” between the laser rotating plane and the platform surface.
2. Set the locking knob to “OFF” position, and place the instrument
in vertical position.
3. Rotate the vertical adjusting knob to center the bubble.
4. Measure the distance “H2” between the top laser beam and
the platform surface.
5. Mark E in the position that is equal to (H1-H2) under the point O.
H1
H2
E
30’ (10m)
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