TB 9-5220-212-40
(7) Place corner mirror approximately 45 degrees from longitudinal axis of
autocollimator.
NOTE
Angle of corner mirror to longitudinal axis of autocollimator
varies according to position of autocollimator in relation to line
being measured.
(8) Zero in autocollimator and corner mirror with carriage at first station (0-1).
(9) Prepare tables exactly as shown in sample tables 4, 5, and 6, completing
column 1 as determined by the number of stations for each line being calibrated. Be certain
to record the direction the lines are run.
NOTE
The first station number is 0 and is added for computation
purposes. Insert 0 in columns 2 through 5 for station 0. For
both diagonal lines, insert 0 in columns 2 through 7 for
station 0.
(10) Measure angular displacement and record in column 2 for station 1.
(11) Advance carriage to each station on line and record angular displacement in
respective table.
NOTE
After the last reading of a respective line, move the carriage
back to the first station and take another reading. If the
reading is not within 0.5 seconds of arc of first reading, repeat
the line readings.
(12) Repeat technique of (4) through (11) above for each line in (3) above.
(13) Calculate the angular displacement for each station in column 3 by subtracting
the value of station 1, column 2, from the value of each station in column 2. Record the
results in column 3 with proper sign.
NOTE
Refer to sample tables.
(14) Calculate values for column 4 by multiplying each value in column 3 by a factor
of 5, 10, 15, or 20 as determined by the respective 1-, 2-, 3-, or 4-inch carriage used in
(1) above.
NOTE
Record value to nearest whole number. The carriage used in
sample table is 3 inches.
(15) Calculate values for column 5 as indicated in (a) through (d) below:
(a) Add column 4, station 0 and station 1 values, and enter sum in column 5 for
station 1.
(b) Add column 4, station 2 value, to column 5, station 1 value.
(c) Enter sum in column 5 for station 2.
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