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Grade Setting Error
Perform the following check only after completing “Horizontal Calibration” and
“Horizontal Rotation Cone Error”.
(1) Checking
1 Securely position two nails or stakes exactly 30m (93 ft) apart. These positions will be called
Nail 1 and Nail 2.
2 Set up the instrument on a tripod approximately 1m to 2m (3 ft to 6 ft) in front of Nail 1 on the
line created by Nail 1 and Nail 2. Position the instrument so the “X-” axis is directly on the line
created by Nail 1 and Nail 2.
3 Turn on the instrument and verify the grade setting is 0.00% in both axes. Turn on the LS-70A
laser sensor and set it to high precision detection. Using the staff, read the elevation of the
laser beam in millimeters at Nail 1 and Nail 2. Designate the elevation at Nail 1 as “h1”, at Nail
2 as “h2”.
Due to the accuracy required to perform this check, the staff used in this procedure must
be graduated in millimeters.
Level
sensor
Staff
Nail 1 Nail 2
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