Johnson Level & Tool Mfg. 40-6935 - Manual (Page 23)

©2011 Johnson Level & Tool 23
6. Self-Check & Fine Calibration
• Calibration should be carried out according to the following steps
because each step’s calibration is based on its former one’s result.
Disorder of the steps will default the calibration.
• Tighten the screw after calibration. Be careful not to over tighten
because excessive tightening will damage the thread.
• After calibration, repeat the inspection to make sure that the
calibration has been successful.
Check and Calibrate The Tubular Vial
Checking
• Attach the instrument to a tripod and rough level. Position the
tubular vial parallel to a line connecting any two of the three
leveling screws on the base. Adjust the two leveling screws so that
the tubular bubble is centered.
• Turn the instrument 180º and check if the bubble remains at center.
Calibrating
• If the bubble remains at the center, no adjustment is required.
Otherwise, perform adjustment as follows:
• Using the bubble adjustment screws and adjustment pin, move the
bubble towards the tube center for half of the error.
• Turn the leveling screw to correct the other half of the error so that
the bubble is centered.
4430H-English_Manuals 2/22/11 11:08 AM Page 23