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Calibration
Equipment needed:
•
Surface plate of superior quality (according to DIN 876/00 or to US standard, quality AA)
•
Dividing head with infinite reading or indexing head and sine bar.
Accuracy of this equipment should be superior or even to 10 sec. of arc. to assure a
calibration which makes sense.
•
Device to mechanically rotate the micrometer shaft at a speed of less then 100 rev./min.
(e.g. drill press with flexible socket elongation and metric socket 13 mm)
Calibration procedure:
1.
Mechanically rotate the micrometer shaft (at max. 100 rev./min.) for at least 20 complete
rounds on the main hub. (Clinometers due for recalibration may have been used at a very
small portion of the total measuring range for the overall service time. This may have built
up deposits of dried grease causing the Clinometer to fail calibration at this points. The
suggested preparation will smooth out such deposits and may also remove small damages
resulting from careless reengaging of the gears.)
2.
Visually inspect the instrument for obvious damages. On the surface plate, check the
geometry of the measuring base. The instrument should rest on the surface without any
wobbling.
3.
Adjust the surface plate to as horizontal as possible in both directions. Set the Clinometer
to zero, (raising scale) and check for accuracy of zero. Use "reversal method" to cancel out
rest errors in plate levelling. The tolerance is 1/5 of a vial division.
4.
Place the Clinometer on the infinite divider head or on the sine bar and check for errors
within one turn of the micrometer drum. The tolerance is 1 graduation. Errors at this point
may be due to inoperative spring loading of the ball pan at the bottom bearing or are due to
bending of the worm shaft after a drop.
5.
Place the Clinometer on the infinite divider head or on the indexing head. Check for errors
in absolute readings. Assure that the zero of divider is identical with zero of the Clinometer
under inspection. Assure that the Clinometer is correctly aligned on the divider head.
Tolerance is 1 ½ min. arc.
Corrections of small errors can be made as described here after. For larger corrections or if
irregular deviations are present, the Clinometer must be rebuilt at the factory if this is
economically reasonable.
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