The test
A shim has been made which can be fixed to the azimuth track. It is made of shim stock 0.004" thick. A test was run where the shim was fixed to the track and wheel 3 of the telescope was run over it with the left hand inclinometer active and with the radial arm inclinometer on the arm leading to wheel 3. Two short inclinometry runs were done, the shim was removed, and two final runs were done.

There was a problem with the inclinometers - when the spare inclinometer was moved to the radial arm position it was found that the input to the DGH module for the x axis was reading 0.004 volts and was not affected by the adjusting screws on the inclinometer mount. We concluded that there was a problem with that channel and so we rotated the inclinometer so that its Y axis was oriented along the radial arm.

The results were stored as shimtest2.dat to shimtest5.dat. Shimtest1.dat was an early run with the spare inclinometer still on the left-hand A frame and inactive.

Results
Figure 1 shows the radial arm results, including a difference plot between runs 3 and 4 - chosen because the slopes of their baselines were similar. The calibration factor is derived as follows. 0.004" = 0.104 mm, and the height of the shim as seen from run 3-4 is 4.2 arcsec.

Hence the calibration of the radial arm inclinometry is 1 arcsec = 24.8 microns.

It is also interesting to note the curves on the walls of the shim profile in the plot. Would these be reproduced in a CCW test? Is there some information in here about the CW-CCW issue?

Figure follows