Elevation drive alignment

After adding 1000lb of counterweight we ran a balance test using the scale. We measure the force to hold the telescope still at several elevations. While driving the elevation between two positions someone noticed that the El drive was walking far enough off to drag the drive mount into the side of the primary friction wheel. This must have been happening for awhile, because the paint is scratched off all along that side.



The azimuth drive avoids this problem by holding the wheel in place with a pair of jack screws above and below the tensioner.



Al and Brian were able to adapt that to the El drive. In a day they had welded up new brackets and punched holes into the back of the boom to mount them. We've run the elevation quite a bit since then and the alignment is holding steady.


We went up onto one of the BIMA platforms while they were shutdown for generator maintenance to check out their drive, which ours is modeled after. Huan noticed that the two jack screws touch the same plate, so that they are very close together, while ours are fairly far apart. That constrains the wheel from turning, which could cause long term problems.

We're going to try pressure sensitive tape to check uniformity of the contact, then we'll see if the system needs improvement