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RA spikes towards west

 

Hi!

I seem to have run into a problem where I think I'd need some smart input. I've cleaned and relubed my G11, put everything together and adjusted the RA worm as usual. Now I am also running a somewhat heavier side-by-side setup. Carefully balanced in 3 directions. I have an OPW (new design) with a high precision worm. Non-tucked motors. There is a belville washer in the OPW.

What I get is spikes in the west direction, if I read it correctly. See the last 3 guiding sessions in the attached PHD2 logfile, or the attached screenshot of one of them. There are a few spikes in the other direction as well.

Now, I'm surprised that these are in the west direction. My thinking is that if there were something in the way, if the worm was not clean, or if there was a problem with bearings or something else, these would cause friction and spikes in the east, not the west, direction.

I've been playing with:

- adjusting worm against ring gear, so I can easily rotate it but not more play than that

- adjusting the tightness of the clutches - thinking this was sticktion. But it seems this far not to make a difference. Loosening or tightening - no perceptible change.

- cables etc - I can not see anything that would cause problems, and again, is this not in the wrong direction for that?

And I should mention that I was imaging M27, relatively high in the sky, and it was no perceptible wind at all.


So: I think I have experimented with "the usual" suspects of bad guiding behavior on the G11, and need some help thinking about what else this could be. Should I dismantle it all again, clean and relube? Or what could cause this kind of behavior? What am I missing here?



Magnus
 

Hi Magnus,

Given all that you have done, I doubt it is the mount drive.... but other ideas follow....

The camera optics are very sensitive to any mechanical looseness.??

When I've gotten glitches in my autoguider camera tracking, I often traced it to a slight wiggle in some one of the 1.25 inch tube or lockdown screws.? I doubt it really is the drive itself.? Last night I found a wiggle in a 90 degree?angle prism diagonal.??

My main deep sky cameras have 2 inch round nosepieces, but even those can loosen up.?

Tiny thumbscrews ...??
I often replace tiny thumbscrews with larger 6-32 or maybe 8-32 pointed end setscrews. ( I think I did that with some Oldham couplers too. I could not get the tiny Allen head wrench to really grab the tiny setscrew.? ?It pays to have a tap and die set, drill and number drill assortment around!)

Hope you solve your glitch trouble,

Michael



On Tue, Aug 4, 2020, 3:52 AM Magnus Larsson <magnus@...> wrote:
Hi!

I seem to have run into a problem where I think I'd need some smart
input. I've cleaned and relubed my G11, put everything together and
adjusted the RA worm as usual. Now I am also running a somewhat heavier
side-by-side setup. Carefully balanced in 3 directions. I have an OPW
(new design) with a high precision worm. Non-tucked motors. There is a
belville washer in the OPW.

What I get is spikes in the west direction, if I read it correctly. See
the last 3 guiding sessions in the attached PHD2 logfile, or the
attached screenshot of one of them. There are a few spikes in the other
direction as well.

Now, I'm surprised that these are in the west direction. My thinking is
that if there were something in the way, if the worm was not clean, or
if there was a problem with bearings or something else, these would
cause friction and spikes in the east, not the west, direction.

I've been playing with:

- adjusting worm against ring gear, so I can easily rotate it but not
more play than that

- adjusting the tightness of the clutches - thinking this was sticktion.
But it seems this far not to make a difference. Loosening or tightening
- no perceptible change.

- cables etc - I can not see anything that would cause problems, and
again, is this not in the wrong direction for that?

And I should mention that I was imaging M27, relatively high in the sky,
and it was no perceptible wind at all.


So: I think I have experimented with "the usual" suspects of bad guiding
behavior on the G11, and need some help thinking about what else this
could be. Should I dismantle it all again, clean and relube? Or what
could cause this kind of behavior? What am I missing here?



Magnus
Sonny Edmonds
 

How is your imaging?
Just because you are getting some jags does not mean you have a problem.
If it shows in your imaging and is insurmountable in processing, that's a problem.
But in my experiences, slightly wiggly-jiggly PHD graphs haven't shown me to be a major concern.

But then, it may be worth noting my delete key is worn smooth and is unreadable now.... ;^0
;^0 LOL!
--
SonnyE


(I suggest viewed in full screen)
 

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Hi!

This clearly affects my imaging. The spikes produce doubled stars, so to speak. Subs not usable. So it needs to be fixed.

I totally agree on the slightly wiggly-jiggly graphs :) But this one needs fixing.

Magnus


Den 2020-08-04 kl. 21:54, skrev Sonny Edmonds:

How is your imaging?
Just because you are getting some jags does not mean you have a problem.
If it shows in your imaging and is insurmountable in processing, that's a problem.
But in my experiences, slightly wiggly-jiggly PHD graphs haven't shown me to be a major concern.

But then, it may be worth noting my delete key is worn smooth and is unreadable now.... ;^0
;^0 LOL!
--
SonnyE


(I suggest viewed in full screen)

 

Hi!

Michael :)

Given all that you have done, I doubt it is the mount drive...
Thanks. I was only thinking mechanics. But there are other things. And what might cause problems when you're not thinking of it?

PEC

Turns out, I had PEC turned on. But it should be off. As I am fiddling with the mount, I have no good PEC curve for the moment. But it was on. That d***ed "Turn PEC on on boot".....

Now PEC is off. And so are the spikes. Mystery solved, it seems :)

A very happy

Magnus
 

O.M.G.
PEC spikes!!!
I'd never ever guess that one!

So many Sci Fi movies have the same theme: glitches in the machine code.? From Westworld to.... you name it.??

I was also thinking of the great movie Forbidden Planet and the "monsters of the Id".... Maybe your Id monster turned in the PEC checkbox?!

So happy you solved your spikes issue.

Stay well, Magnus!

Michael



On Tue, Aug 4, 2020, 2:15 PM Magnus Larsson <magnus@...> wrote:
Hi!

Michael :)

> Given all that you have done, I doubt it is the mount drive...

Thanks. I was only thinking mechanics. But there are other things. And
what might cause problems when you're not thinking of it?

PEC

Turns out, I had PEC turned on. But it should be off. As I am fiddling
with the mount, I have no good PEC curve for the moment. But it was on.
That d***ed "Turn PEC on on boot".....

Now PEC is off. And so are the spikes. Mystery solved, it seems :)

A very happy

Magnus
Sonny Edmonds
 

See there? You did fix it yourself, Magnus.

And I learned something about PEC and the Kingdom of Auto-on.
Like don't go there. ;^)

Do you suppose PEC would work well again if you retrained it?

Glad you got it fixed!
--
SonnyE


(I suggest viewed in full screen)
 

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Hi!

Yes, well, I didn't fix it myself :) I needed some thoughts from someone else to get some new ideas, to set me off in a different direction. Actually, I quite often find that just asking about something is sufficient to find a new direction and solving or understanding something. Questions have a power of themselves :)

I am sure PEC will work when I train it again!? I use PEMPro for doing that, regularly (need to redo quite often as I tend to fiddle with something and then the curve is obsolete...)

But now I will test for PE on different worms, extensively. And try to see if it is possible to catch the outer nebulosity of M27 from a very light polluted suburban area in Sweden :)

Beware of Auto-on!


Magnus


Den 2020-08-05 kl. 11:23, skrev Sonny Edmonds:

See there? You did fix it yourself, Magnus.

And I learned something about PEC and the Kingdom of Auto-on.
Like don't go there. ;^)

Do you suppose PEC would work well again if you retrained it?

Glad you got it fixed!
--
SonnyE


(I suggest viewed in full screen)

 

Hej Magnus!

OMG I had issues since two weeks I couldn't figure out. I encountered 9" spikes while guiding out of nowhere. Also it was impossible to polar align using a plate solving solution near Polaris (Ekos in my case), changes were somehow random sometimes undercorrecting, sometimes overcorrecting, sometimes moving at the opposite of the correction
Like you went into tuning and re-tuning, but I thought it was good.

Long story short I read your post and realized I had reset the mount two weeks ago at which point PEC got activated (with a very bad PE recording on the SD Card).?I can't wait to try it but am very confident this was it.

Thank you so much! See, you even solved my issue :-D

Also many thanks to Michael and Sonny, and obviously Brian which is helping me a lot too.

Cheers,

Carl
 

Nice Carl!

A Bad PEC is worse than no PEC at all



On Tue, May 4, 2021 at 8:04 AM Carl Bj?rk <carl.bjork@...> wrote:
Hej Magnus!

OMG I had issues since two weeks I couldn't figure out. I encountered 9" spikes while guiding out of nowhere. Also it was impossible to polar align using a plate solving solution near Polaris (Ekos in my case), changes were somehow random sometimes undercorrecting, sometimes overcorrecting, sometimes moving at the opposite of the correction
Like you went into tuning and re-tuning, but I thought it was good.

Long story short I read your post and realized I had reset the mount two weeks ago at which point PEC got activated (with a very bad PE recording on the SD Card).?I can't wait to try it but am very confident this was it.

Thank you so much! See, you even solved my issue :-D

Also many thanks to Michael and Sonny, and obviously Brian which is helping me a lot too.

Cheers,

Carl



--
Brian?



Brian Valente
portfolio

 

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Hej :)

Good to hear!

Best,

Magnus


Den 2021-05-04 kl. 17:03, skrev Carl Bj?rk:

Hej Magnus!

OMG I had issues since two weeks I couldn't figure out. I encountered 9" spikes while guiding out of nowhere. Also it was impossible to polar align using a plate solving solution near Polaris (Ekos in my case), changes were somehow random sometimes undercorrecting, sometimes overcorrecting, sometimes moving at the opposite of the correction
Like you went into tuning and re-tuning, but I thought it was good.

Long story short I read your post and realized I had reset the mount two weeks ago at which point PEC got activated (with a very bad PE recording on the SD Card).?I can't wait to try it but am very confident this was it.

Thank you so much! See, you even solved my issue :-D

Also many thanks to Michael and Sonny, and obviously Brian which is helping me a lot too.

Cheers,

Carl

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