A-A-52024
marked so that 0.50 degrees can be estimated. There shall be no apparent difference in the reading of the ends of the needle. The needle shall be equipped with a lift mechanisms to secure it when not in use. The damping time of the needle shall not exceed 15 seconds when the needle is deflected.
Jacob’s staff. The Jacob’s staff shall be of hardwood or nonferrous metal staff, not less than 54 inches long, threaded 0.625 – 11 UNC – 2A for a type I compass and 0.25-20 UNC-2A for type II compass to mate with the female end of the ball and socket joint or ball and socket head. The other end of the staff shall be equipped with a pointed metal shoe for penetrating the ground. The staff shall be one piece or collapsible and shall weigh not more than 4 pounds.
Ball and socket joint or ball and socket head. A ball and socket joint or ball and socket head to attach the compass to the Jacob’s staff shall be constructed to permit tilting the compass through 90 degrees from the horizontal to the vertical plane and also permit full rotation of the compass in azimuth through 360 degrees. The ball joint shall equipped with a knurled collar to tighten the joint in tilted position and a knurled thumbscrew to tighten the joint in the azimuth position. The male end of the ball joint shall be threaded 0.50-20 UNF-2A to mate with that in the compass base female recessed fitting, which shall be at least 0.250-inch deep for a type I compass and the type II compass shall be furnished with a bracket to attach the compass to the ba;; joint. The other end of the ball joint shall be threaded 0.625-11 UNC-2B for a type I compass and 0.250-0 UNC – 2B for type II compass to fit the Jacob’s staff
Carrying case. When required. A sewed leather case with a sling strap shall be provided to hold the compass. When applicable, the carrying case shall be of case leather, mildew resistant treated, grain side smooth with the sides of the case formed. A hold down strap and a nonferrous metal fastening stud shall be provided for the closing flap.
Tolerances. The tolerances for the beveled knurled revolving ring, compass dial, and raised compass ring shall be ±10 minutes per degree graduation, with no more than ±30 minutes per quadrant. The error shall be noncumulative over the entire circle.
Specific salient characteristics.
Type I, surveyor’s magnetic compass using ball and socket joint.
Beveled knurled revolving ring. The beveled, knurled revolving ring shall be aluminum and shall be graduated in single degrees both ways from zero in four 90-degree quadrants, with a sighting mark at each quadrant.
For Parts Inquires submit RFQ to Parts Hangar, Inc.
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business