Johnson Level & Tool Mfg. 40-6610 - Manual (Page 10)

10 ©2005 Johnson Level & Tool
4. Turn the unit 180°, have the cross located on staff B and note
the value of b1.
5. Move the tripod to
change the distance
between the unit and
staff A to 2 ft. (0.6m).
6. Repeat steps c, d and
note down a2, b2.
7. Calculate:
(a1-a2)-(b1-b2)=e
Note: If e>0.047" (1.2mm), the unit accuracy is beyond tolerance,
reference section 12 of this document.
Horizontal Line Accuracy Self-Check
1. Find a wall and set up the unit at 16 ft. (5m) away from the wall.
2. Set the bracket on the tripod or elevating pole, and put the unit
into the bracket and orient it at the wall.
3. Switch on front horizontal beam button H and front vertical beam
button V1, and take the cross on the wall as point A.
4. Mark out point A and point M
on the horizontal line, and the
distance between the two
points is about 8 ft. (2.5m).
5. Turn the unit to move the cross to point B that is 16 ft. (5m) away
from point A.
6. Measure the distance e between point M and the horizontal line.
Note: If e>0.118" (3mm), the unit accuracy is beyond tolerance,
reference section 12 of this document.
Survey-staff A Survey-staff B
40-6600_6610 4/22/05 4:56 PM Page 10