Re: Sawtooth pattern in DEC
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Hi Arun, Well, a 3 minute period is not the 4 minute worm period, so its not the RA worm, Oldham coupler, or gearbox.? And it's a DEC period not an RA period anyway.? ?It's also not PEC as this only corrects the RA drive.??It's a good puzzle.? Did you drift align your polar axis before imaging?? If not, redo the drift alignment.? If your polar axis is off (and it has to be off) you'd need these DEC corrections.? It seems that PHD2's correcting, maybe overcorrecting, then has to correct again. _____ and/or_______: Second question is: can this be a mechanical issue, not PHD2 software per se?? To check that, grab your scope front and back and try to wiggle it on the DEC axis.? Can you move it?? If so, you should try to eliminate this mechanical hysteresis.?? There are two causes of the mechanical hysteresis: 1) the worm to ring gear spacing.? You adjust that on non SLW units by? a) use a feeler gauge to measure the space between the right side worm bearing block and the vertical plate next to it.? Write that down. b)? Try to loosen the 2 bottom hold-down bolts, and gently rotate in the worm using the left hold bolt as a pivot point.? Use the feeler gauges to determine if you got closer. But don't force the worm in too tightly.? c) retighten the mounting bolts and? d) check the worm for "Stall" or "Lags" messages on Gemini. 2) second cause of hysteresis is caused by the worm sliding along it's axis.? See if you can observe this when you rotate the scope.? If you have this worm shifting, and an SLW unit, contact the factory for advice.? ?If you don't have an SLW on this axis, see my earlier PDF on how to rectify that issue. All the best, (and happy imaging and good health!!!) Michael On Wed, Jun 17, 2020, 4:10 PM Arun Hegde <arun.k.hegde@...> wrote: Brian, |
Michael Herman