Johnson Level & Tool Mfg. 40-6639 - Manual (Page 16)

16 ©2012 Johnson Level & Tool
8. Self-Check & Fine Calibration
IMPORTANT: It is the responsibility of the user to verify the
calibration of the instrument before each use.
Accuracy Check
1. Set the device on a platform, a minimum of 5 meters away from
an indoor wall, with laser squarely facing wall.
2. Turn the device on, and after it self-levels, make a mark on the
wall (Label this mark ‘A’), then draw a vertical line through ‘A’.
3. Turn the device 90°, and after it self-levels, make a mark at the
intersection of the laser line/vertical line. (Label this mark as ‘B’).
Do the same two more times, labeling the marks as ‘C’ and ‘D’.
4. Measure the distance between the two points with the greatest
distance among A, B, C, D. This will be measurement ‘h’. If
‘h’=2mm, the accuracy of the instrument is within spec.
If ‘h’> 2mm, the accuracy of the instrument is out of tolerance,
and adjustment is necessary.
Adjustment of Self-Calibration
According to the results of #4 above, mark ‘O’ at ‘h’/2. ‘h’/2 is the
center of the highest and lowest points among A, B, C, D.
1. Aim the self-calibration aperture 1 of instrument to the
wall, and adjust to make the laser line meet ‘O’.
2. Aim the self-calibration aperture 2 of instrument to the
wall, and adjust to make the laser line meet ‘O’.
6249H_Manuals 10/18/12 2:49 PM Page 16