Re: Backlash


Mike Dodd
 

On 3/14/2021 5:28 PM, Tom Blahovici wrote:
I have this mount and use it for imaging.
Which mount would that be?

I have backlash of 2 seconds in Dec....
My mount had a 2.8 arc second peak to peak periodic error without PEC.
Periodic error has nothing to do with Dec, only RA. If your mount requires Dec corrections, that indicates your polar alignment should be adjusted.

Dec adjustments should be infrequent. Do your Dec corrections need the same 2-second backlash in both directions, or only one? IOW, is the correction with the backlash the same in both directions?

If so, it sounds to me like your work-to-worm-wheel mating is too loose, and needs adjusting. If not, that sounds like a balance issue, which would manifest itself only while pointing to certain areas of the sky.

--- Mike

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