erratic guide eq8
pkorama pkorama
bw_msgboard
Hi PK. As in most of these situations, your problems are not with the guide settings – they are with the mount. In order for us to give you our best advice, you need to upgrade to the latest PHD2 release and reset all your guide parameters to their default values. Since your set-up has a lot of backlash and some other problems, I recommend that you install the latest PHD2 dev release:
https://openphdguiding.org/development-snapshots/
And then adjust your EQASCOM settings to match these guidelines:
https://github.com/OpenPHDGuiding/phd2/wiki/EQASCOM-Settings
In particular, you want to increase the mount guide speed up close to 1x sidereal. And you should probably follow the recommendations here, particularly with respect to doing calibrations:
https://openphdguiding.org/phd2-best-practices/
Then we can try to help you track down some of the problems we can see here. To start, the RA tracking seems to encounter some very large errors:
These are huge errors, not anything that can be guided out effectively. Perhaps something is hitting or interfering with the mount, something is loose on the OAG/camera assembly, or there’s something wrong with the RA drive system. We don’t see these in every guide session but they really shouldn’t happen at all. Here’s another peculiar event in RA when guiding was disabled:
Why did the mount/scope suddenly lurch to the west by 20 arc-sec?
As I mentioned before, your mount appears to have a lot of Dec backlash, a fairly common problem. The latest PHD2 dev release should do a better job of measuring that. Also, if you follow the recommendations and run the mount at the higher guide speeds, the backlash delay will decrease proportionately. You should run the Guiding Assistant for a good long time, probably 2 worm cycles, so we can get a better view of your mount’s native performance. Only then is it possible to make sensible recommendations about how to move forward. We can help you analyze the results, but you should start using the new Help/Upload Logs feature to send us your log data.
Hope this helps, we’ll be glad to help you understand the results you get after making the above changes.
Bruce
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pkorama pkorama
bw_msgboard
The big spikes in RA are still evident in the early sessions, as you said:
This is a mechanical problem of some kind. It could conceivably be caused by dirt or some other form of foreign material in the gears or by some other problem in the RA drive system. If it’s caused by some kind of crud in the gears, you might be able to clear it by running the mount at slew speed from horizon to horizon a couple of times. Or you might be able so see what’s wrong just by removing the covers on the drive system and looking at what happens in there as you move the scope. I think others have seen problems like this that were found to be caused by a too-tight mesh in the gears. I think you’ll have to get advice from one of the EQ mount forums or perhaps the manufacturer, there’s really not much else we can see from the application software level.
As I said before, fooling around with guide algorithm choices and parameters isn’t going to help with this – it is more likely to just create other problems once you get past this mechanical issue.
Hope you can find the problem fairly easily,
Giorgio
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bw_msgboard
I guess balance might affect the underlying problem but I don’t really know. Unless you’re significantly out of balance, I’d suspect something else. My guess is that doing the meridian flip positioned the RA gear train into a significantly different orientation – the relative rotation angles of the worm and worm wheel in particular. I guess we also can’t be sure that it’s dependent on side-of-pier because this is only one test – you could certainly test for that though. When any of the gears are slightly out of round or aren’t completely concentric with the shafts they drive, the meshing tightness can change depending on the various rotation angles of the gears. But I’m just a software guy, you probably want to get advice from someone who really understands the mechanics of the mount. We’ve heard from users who have opened up these gear boxes and were pretty unhappy with how they were assembled – and just re-assembling and lubricating them with some care improved the performance.
Hope you can get it resolved,
Bruce
