A time for work and a time for no play

Today we discovered the reason why we have play (“slop”) in the RA axis. The friction clutch has four through-holes that pass four bolts from the outer most plate through the large RA gear and to a fixed back plane attached to the RA armature. Springs provide the tension. The through-holes are a bit too large. So when RA motion is engaged, <1mm on the plate translates to ~5mm travel at the telescope before a solid connection is made. While this does not affect the guided function of the RA motor, it makes for frustrating manual centering. We went to Usa River to try and find a thin sleeve or bushing, but came back empty handed. We will take the outer clutch plate to the Arusha Technical University and use their mill to prepare a more sophisticate interface between the plates to eliminate the RA axis play.

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