Under normal operation if the clutch is never released and the relationship between the worm gear and CWD is maintained all the wear on the worm gear occurs on only one side over some portion less than 180 degrees. Over time the condition you report of a 'tight worm' at 180 degrees from CWD? is expected. Normally I would expect no wear on the ring gear anywhere around 180 degrees from what is normally your CWD position. Long period PE and PEC is impacted by absolute ring gear position because of the impact on worm mesh. This is somewhat mitigated by spring loading the worm so it can float in and out to maintain mesh and consistent worm/worm gear pressure.? ?Any shift in the DEC axis relationship to the worm gear by relaxation of the RA clutch will throw off your PEC because the absolute position of the worm gear has changed. Even with spring loading, there will be slight differences.
The problem with the clutched design is that there is no index of the DEC axis (CWD) to the RA ring gear absolute position. .? This destroys the 'sync' for guiding, PEC and backlash along with your worm mesh adjustment.
So, how can we set a consistent 'start position' for the mount that maintains the relationship???
I suggest the following:
Scribe the worm gear along it's top surface where it can be seen with the worm cover off. For some worm gear types where the cover cannot be removed a notched window may need to created to see this mark. The mark needs to be able to be matched to a specific mark on the mount housing at perhaps an existing landmark on he housing (window edge?) .?
Creae an index mark to match the DEC axis position to a known orientation to the mount RA housing. You might need to attach and extend a pointer.??
Although less critical for DEC, a similar situation exists because of the relationship between worm mesh and backlash.?
A similar solution can be applied.
Michael
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