Terrible RA guiding

[Shimonu]

I've tried adjusting my RA axis so I don't feel and play. I thought I solved it by binning my guiding camera but that seems to have just changed the numbers without improving the actual guiding. The calibration in Ekos seems to go through successfully but I'm not sure how I read the plot.

I've included a picture of what the guiding looks like from Ekos. I'm getting really desperate, I'd really like to understand the issue before I start replacing things on random.

[michael8554]

A little more info would help.

What exposure ?

Which is RA, which is Dec ?

I think from the Dither figures that RA is Blue ?

There are excursions of up to 7.5arcsecs that are taking about 5 exposures to correct.

Causing RA to fly over the other side of the axis up to 7.5arcsecs, and about 5 more exposures pass before RA is corrected.

So I'd say RA is loose and has Stiction.

If you have any sort of GuideLog it would be far more instructive than screenshots.

Michael

[Shimonu]

45 minutes ago, michael8554 said:

A little more info would help.

What exposure ?

Which is RA, which is Dec ?

I think from the Dither figures that RA is Blue ?

There are excursions of up to 7.5arcsecs that are taking about 5 exposures to correct.

Causing RA to fly over the other side of the axis up to 7.5arcsecs, and about 5 more exposures pass before RA is corrected.

So I'd say RA is loose and has Stiction.

If you have any sort of GuideLog it would be far more instructive than screenshots.

Michael

Sorry for the lack of info. I've been trying to get some help but got the feeling guidelogs were not appreciated as I didn't get any response. I'll add the log from the picture. So I was using mostly 2s exposure and trying 1.5s to see if it made any difference. You're very much correct that blue is RA.

I appreciate the input. If I'm understanding you the RA axis is loose in some places but getting stuck in other places? I guess it might be worth going for the belt mod as I'll likely need to take it apart and inspect it anyway.

 

guide_log-2021-08-05T00-15-32.txt

[newbie alert]

Take it if you're talking about a belt mod that it's a skywatcher?

Belt modding won't stop stiction, sounds like it could be gear mesh/ binding, or clutch too tight causing the ring gear pushed to one side, or taper bearing locking nut done up too tight...

Could be lots of things

[powerlord]

It looks bad enough it might be worth just using controller to move RA slowly, and look closely.

[Shimonu]

9 minutes ago, newbie alert said:

Take it if you're talking about a belt mod that it's a skywatcher?

Belt modding won't stop stiction, sounds like it could be gear mesh/ binding, or clutch too tight causing the ring gear pushed to one side, or taper bearing locking nut done up too tight...

Could be lots of things

But essentially I should take it apart, inspect and feel that everything is in good condition and moving smoothly?

1 minute ago, powerlord said:

It looks bad enough it might be worth just using controller to move RA slowly, and look closely.

Sorry, I'm not sure I'm following. Look at what exactly?

[newbie alert]

51 minutes ago, Shimonu said:

But essentially I should take it apart, inspect and feel that everything is in good condition and moving smoothly?

 

Depends on what  you did to fix the issue you had.. has it got better or worst?

[Shimonu]

22 minutes ago, newbie alert said:

Depends on what  you did to fix the issue you had.. has it got better or worst?

I haven't done much. Previously I've just noticed the RA had some play when trying to move it with my hands and I've adjusted the grub screws to tighten the worm drive until I couldn't feel any play at least. Otherwise I've only done stuff with the software and try to interpret logs. I haven't seen any change at all really.

[Seelive]

Have you over-tightened it? Backlash in the RA isn't so much of a problem especially if the balance is set slightly east heavy.

Edited August 5, 2021 by Seelive

[Shimonu]

14 minutes ago, Seelive said:

Have you over-tightened it? Backlash in the RA isn't so much of a problem especially if the balance is set slightly east heavy.

I don't think so, I was really making sure I was only tightening enough to make the slop disappear. I went back a few times so I could feel it again and just tightened a very small amount to see when it went away.

[newbie alert]

2 hours ago, Shimonu said:

I haven't done much. Previously I've just noticed the RA had some play when trying to move it with my hands and I've adjusted the grub screws to tighten the worm drive until I couldn't feel any play at least. Otherwise I've only done stuff with the software and try to interpret logs. I haven't seen any change at all really.

Did you slightly slacken the bolts on the worm housing?

[Shimonu]

8 minutes ago, newbie alert said:

Did you slightly slacken the bolts on the worm housing?

I found a tutorial and loosened them and retightened just until there was resistance.

[Guest]

I've got a similar problem with my HEQ5. DEC looks good but RA is rubbish.  I've installed the belt drive mod but haven't been able to test it yet.

What I wanted to say was that I understand that as far as RA guiding  is concerned backlash in RA is not important. The reason is that RA should always be tracking forward. The guiding pulses only make it go faster than sidereal or slower than sidereal but always in the same direction so backlash shouldn't matter.  Like you I've adjusted the backlash in RA as small as possible and I'm wondering if I've overdone it. I have an idea to test the theory by slackening it off to see what happens. I just need a clear night to try it out.

The other thing is that they say that you should adjust the balance of the scope so that it's tending towards east. In this way you can avoid the situation where the RA is bouncing back and fore across the backlash.

 

[michael8554]

Redacted

 

Edited August 7, 2021 by michael8554

[newbie alert]

A couple of strip down videos.. I've watched the eq6 r pro one.. shows abit about worm adjustments..

 

 

[newbie alert]

 

[Shimonu]

31 minutes ago, michael8554 said:

Some strange entries in your PHD2 GuideLog:

You carried out Calibrations with different Calibration Step sizes, 50 pixels, 30 pixels, before setting it at the correct 25 pixels.

I don't see that the guidecam was Binned.

Earlier Calibrations were carried out with the EQMOD HEQ5/6 (ASCOM) mount driver.

But later ones were carried out with the ZWO ASI290MM Mini (ASCOM) camera driver as the mount driver ???

Which maybe has reverted the guiding from ASCOM to ST-4 ?

Given the wrong settings and random adjustments of the PHD2 settings while guiding, I don't think any of your guiding is worth analysing.

I suggest you go intro the PHD2 Help menu and have a good read of the Help and How To guides before doing any more guiding, the PHD2 Guide Assistant will suggest settings for you.

Start here:

https://openphdguiding.org/phd2-best-practices/

Michael

 

 

I'm not sure what you're looking at, a lot of this sounds strange to me. I'm working with indi drivers and an NEQ-6, I don't have any 290MM mini, just a 294MM Pro or a 120MM-S. Also I'm using the internal guider of Ekos.

Anyway, I've gotten the RA axis apart and noticed the worm shaft wasn't turning smoothly. Hopefully this is the issue. I just needed to loosen the locking ring for the shaft. There are some pretty nasty tool marks on the end caps from the previous owner and I suspect he's been in there trying to do god knows what.

[michael8554]

15 hours ago, Shimonu said:

I'm not sure what you're looking at, a lot of this sounds strange to me. I'm working with indi drivers and an NEQ-6, I don't have any 290MM mini, just a 294MM Pro or a 120MM-S. Also I'm using the internal guider of Ekos.

Apologies Shimonu,

That was someone else's Guidelog I selected in Log Viewer.

Michael

[Shimonu]

41 minutes ago, michael8554 said:

Apologies Shimonu,

That was someone else's Guidelog I selected in Log Viewer.

Michael

No worries, I appreciate you taking the time.

[newbie alert]

16 hours ago, Shimonu said:

 

I'm not sure what you're looking at, a lot of this sounds strange to me. I'm working with indi drivers and an NEQ-6, I don't have any 290MM mini, just a 294MM Pro or a 120MM-S. Also I'm using the internal guider of Ekos.

Anyway, I've gotten the RA axis apart and noticed the worm shaft wasn't turning smoothly. Hopefully this is the issue. I just needed to loosen the locking ring for the shaft. There are some pretty nasty tool marks on the end caps from the previous owner and I suspect he's been in there trying to do god knows what.

Sounds like it could be the culprit.. Hope it's the solution 

[Shimonu]

5 minutes ago, newbie alert said:

Sounds like it could be the culprit.. Hope it's the solution 

Just waiting for a clear night to test it out. Forecast shows no opportunity any time soon.. 😕 Hopefully it's wrong.

[michael8554]

Hi Shimonu

Here's from YOUR GuideLog:

You never got a decent Calibration, so guiding was bound to be poor:

 

Calibration guide speeds:       RA = 1.6 a-s/s, Dec = 1.7 a-s/s

Guide speeds need to be at least 7.5 a-s/s.

So RA completed in 4 steps W1 to W4.   PHD2 aims for 12 steps, your Guide software may be different.

North took 3 steps N1 to N3, but the Return South path S1 to S7 should have ended back at the intersection of the axis at W1, and ideally taken 3 steps, not 7.

This is an indication of rather large Dec Backlash,.

So I'd concentrate on that rather than RA !

I'm afraid the Logs generated by your Guide Software are sparse on detail compared to PHD2.

But it showed that you Calibrated at Dec = 40, it's best to Calibrate at Dec = 0.

So concentrate on Dec Backlash and larger Guide Rates.

Maybe get some good guiding by tweaking in PHD2, then reverse engineer it to work with your guide software  😆  ??

Michael 

 

Edited August 7, 2021 by michael8554

[Shimonu]

On 07/08/2021 at 14:18, michael8554 said:

Hi Shimonu

Here's from YOUR GuideLog:

You never got a decent Calibration, so guiding was bound to be poor:

 

Calibration guide speeds:       RA = 1.6 a-s/s, Dec = 1.7 a-s/s

Guide speeds need to be at least 7.5 a-s/s.

So RA completed in 4 steps W1 to W4.   PHD2 aims for 12 steps, your Guide software may be different.

North took 3 steps N1 to N3, but the Return South path S1 to S7 should have ended back at the intersection of the axis at W1, and ideally taken 3 steps, not 7.

This is an indication of rather large Dec Backlash,.

So I'd concentrate on that rather than RA !

I'm afraid the Logs generated by your Guide Software are sparse on detail compared to PHD2.

But it showed that you Calibrated at Dec = 40, it's best to Calibrate at Dec = 0.

So concentrate on Dec Backlash and larger Guide Rates.

Maybe get some good guiding by tweaking in PHD2, then reverse engineer it to work with your guide software  😆  ??

Michael 

 

Was finally able to try out the mount after going over it and the guiding has certainly improved. I was able to get 1.1"-1.5" stable and depending on the exposure length. I haven't had a chance to open the logs on the computer yet but the calibration looked pretty bad still. So I'll have to look at that and perhaps the guiding can be improved even more. I'm guessing that ideally it should be a perfect cross?

[michael8554]

8 hours ago, Shimonu said:

I'm guessing that ideally it should be a perfect cross?

My comments are based on my PHD2 experience, I'm assuming a good Cal with your software should look like this, with RA and Dec at 90 degrees:

And the Dec Backlash causes the southward return from the northmost end of the Dec line to wander off like your S1 to S7, instead of retracing the green line to the origin.

But again, your software may Calibrate differently.

Michael

Edited August 12, 2021 by michael8554