4.6.3 Plotting scale flatness .- The test shall be perform by
placing the "11" graduation of the plotting scale at the center of. the
board, and measuring any variation in flatness at the "7" and "15"
graduations of the scale with standard thickness gages. Any error in
flatness shall not exceed the requirements of 3.5.
4.6.4 Parallelism.- Parallelism of the grid lines in relation to
the fiducial edge of the plotting scale shall be tested on the two grid
lines which intersect through the center of the plotting disc. (Rotate
the table 1600 roils to obtain alinement of the perpendicular grid line
with the plotting scale. Use a pocket optical comparator to check errors
in parallelism. Errors shall not exceed the requirements of 3.6.
4.6.5 Accuracy.- The plotting board shall be arranged for two man
operation with the plotting scale and grid lines parallel and a zero
setting on the azimuth scale. With this setting the following procedure
shall be utilized to determine compliance with 3.7:
a. Using the plotting scale, measure off and establish a
7500 meters north of the approximate center of the disk.
b. From the point established above, measure off and establish
a point 15000 meters south.
c. Rotate the plotting disk to 1600 mils and repeat the
procedures in "a" and "b" on the new north-south line.
d. With the table set in this position, draw lines through
the points established on the east-west line.
e. Rotate the board to zero and draw lines through the points
established on the east-west line so as to form a square.
f. Rotate the board to a position where the plotting scale
bisects the corners of the square.
g. Both diagonals, as measured on the scale,shall be in
compliance with the accuracy specified in 3.7.
Use a 2H or softer pencil for drawing or marking on the plotting
disk surface. Erase pencil markings with a soft rubber eraser
void of abrasives or grit.
4.6.6 Torque.- This test shall be performed using a commercial type
inch-pound torque wrench with adapter to accommodate the slow motion knob.
Readings with the torque wrench shall be taken in both directions while
in motion. The torque required to rotate the slow motion knob at standard
ambient temperature and at the extreme temperatures of 3.4.2 shall not
exceed the values as specified in 3.8.1.