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AVX help....Please!

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#1 Philkib

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Posted 16 April 2018 - 12:35 PM

 Hi
Can you help me please? I have an AVX and would like to have the thoughts on the community on an issue I have.
On the AVX there are 2 Orange decorative covers, under each one it covers a tension ring, which in turn one of them covers 3 grub screws. Now the question, how 'tight' should 1) the grub screws be? and 2) tension rings be?
Should they be VERY tight? moderately tight? or just nipped up? I suspect that it should just be nipped up and allow gravity to keep the mount in place when in use, but not sure.

Supplement question would be, how would these grub screws and tension rings effect the over all performance of the mount? as in, if they were set wrongly would that effect the performance with PHD2?

 

Thanks for taking the time to read this post!

 

Keeplookin' up!

 

Phil



#2 sg6

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Posted 16 April 2018 - 12:50 PM

Likely no help, but on the EQ5 + HeQ5 there are 3 grub screws on the Dec weight bar exits, the grub screws on that need to just nip but all 3 nip the same. Not sure of the RA axis.

 

There is also a threaded aspect to it.

 

I found that if one was "tight" then the axis it gripped ended up "bent" and rotation was poor/uneven. Took me about 4 attempts to get it right and the grub screws were actually difficult to get in as the threaded bit they went into were below where the alan key went. Sorry to be unclear but the assembly everything went into was odd.

 

Main thing was just getting the pressure even and so not distorting the axis.

Still not sure it is "right" but it seems to work and is smoother.

 

From reading the Dark Frame site for AVX tuning I gather that teh AVX mount could be unusual in how it all operates:

https://www.darkfram...t/avx-hypertune

 

This part of what they say:

Its a different architecture to the Sky-watchers which we have had much success with, and Im now focusing my energies in doing the same with the Celestron EQ Mounts.

 

So maybe what I have experienced is irrelevant.



#3 Grampa Jim

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Posted 16 April 2018 - 12:50 PM

Hi

The side rings are used to hold a tube which in turn holds the mount so that the polar angle can adjusted.  The grub screws and to a lesser extent the tension rings determine how tight the vertical polar adjustment is - too tight and the mount would be more difficult to polar align.  However, this shouldn't really affect the mount performance, once it is polar aligned.

Good luck.

Jim



#4 CharlesW

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Posted 16 April 2018 - 01:11 PM

You didn’t describe the issue you were having. First thing, a picture of your mount, as set up, is worth a thousand words. Well meaning, but poor setups, account for most early problems imagers face, IMO. Some simple changes, without tightening screws, might fix whatever ills you have. What do your stars look like? Remember, the goal is not to have a pretty graph but round stars. 



#5 Philkib

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Posted 16 April 2018 - 01:14 PM

Hi

The side rings are used to hold a tube which in turn holds the mount so that the polar angle can adjusted.  The grub screws and to a lesser extent the tension rings determine how tight the vertical polar adjustment is - too tight and the mount would be more difficult to polar align.  However, this shouldn't really affect the mount performance, once it is polar aligned.

Good luck.

Jim

Hi Jim

Thanks for your reply, and your assessment is spot on, I was having difficulty in getting any type of polar alignment. I found that there was a lot of play in the altitude axis and thought I had nothing better to do than to tighten them to take up the slack. It did, but then I couldn't get any PA and once 'loosened off' I could get a decent alignment, however, using PHD2 my dec was all over the place... no coincidence I thought. Looking at SG6 above may have a point to look at.



#6 Philkib

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Posted 16 April 2018 - 01:30 PM

You didn’t describe the issue you were having. First thing, a picture of your mount, as set up, is worth a thousand words. Well meaning, but poor setups, account for most early problems imagers face, IMO. Some simple changes, without tightening screws, might fix whatever ills you have. What do your stars look like? Remember, the goal is not to have a pretty graph but round stars. 

 

Hi Charles

 

Thanks for your reply, and I agree totally, round stars are the goal. Sorry if it was not clear, but everything, (stars and graph) are all over the place but I think I'm within touching distance of getting things back on track and only needed a steer on the only part I changed and that was the grub screws.

arrrrrgh why do I keep playing with thingsconfused1.gif  you'd think as you get older you'd learn......lol.gif 



#7 Philkib

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Posted 17 April 2018 - 12:00 AM

Likely no help, but on the EQ5 + HeQ5 there are 3 grub screws on the Dec weight bar exits, the grub screws on that need to just nip but all 3 nip the same. Not sure of the RA axis.

 

There is also a threaded aspect to it.

 

I found that if one was "tight" then the axis it gripped ended up "bent" and rotation was poor/uneven. Took me about 4 attempts to get it right and the grub screws were actually difficult to get in as the threaded bit they went into were below where the alan key went. Sorry to be unclear but the assembly everything went into was odd.

 

Main thing was just getting the pressure even and so not distorting the axis.

Still not sure it is "right" but it seems to work and is smoother.

 

From reading the Dark Frame site for AVX tuning I gather that teh AVX mount could be unusual in how it all operates:

https://www.darkfram...t/avx-hypertune

 

This part of what they say:

Its a different architecture to the Sky-watchers which we have had much success with, and Im now focusing my energies in doing the same with the Celestron EQ Mounts.

 

So maybe what I have experienced is irrelevant.

Thanks for your reply, it certainly is worth me having a look at the way these grub screws are set up and will work on this for the next clear night I have. The intention is to hook everything up to the laptop then work on these grub screws and see if there is an immediate effect with PHD2 when adjusting the pressure. If that makes sense!

As it is just now I'm unable to use the mount for AP and therefore I will try anything to get it to work, I'll post back here once I've tried this out. 

Cheers

 

Phil



#8 jfaldo

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Posted 17 April 2018 - 08:42 AM

I keep re-reading this thinking I'm missing something but I don't think so. This axis should have zero affect on guiding assuming you can get a good pa to begin with.  This point only allows the mount to move in RA when doing a pa and then is locked down tight anyways. The screws you are referring to really only hold things together and put tension on the bearing surfaces to allow some tension on the axis when you are moving it up or down but again after pa is achieved then everything is held down tight by the adjusting knobs and not the bearing surfaces.

 

If you pull this apart you'll see there are indentations in the bearing material indicating they are tightened down fairly tight from the factory. When I tore my mount down and then put it back together I just snugged them up and tested the feel of the movement without the adjusting knobs in place. Set it to move smoothly with some resistance but not loose enough to move on it's own.


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#9 Stelios

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Posted 17 April 2018 - 10:55 AM

DEC all over the place (actually periodic extreme jerks of the order of 40" sometimes) was a problem with *my* first AVX. Both Ed (Thomas) and then Celestron tried to fix it and ended up replacing the mount. The replacement has no issues. 

 

I would suggest returning these screws to approximately their pre-fiddling state, and then posting a PhD2 graph (preferably in a separate post). Don't fall into my mistake--I spent almost 4 months trying to 'fix' the unfixable. 



#10 Philkib

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Posted 18 April 2018 - 12:33 PM

I keep re-reading this thinking I'm missing something but I don't think so. This axis should have zero affect on guiding assuming you can get a good pa to begin with.  This point only allows the mount to move in RA when doing a pa and then is locked down tight anyways. The screws you are referring to really only hold things together and put tension on the bearing surfaces to allow some tension on the axis when you are moving it up or down but again after pa is achieved then everything is held down tight by the adjusting knobs and not the bearing surfaces.

 

If you pull this apart you'll see there are indentations in the bearing material indicating they are tightened down fairly tight from the factory. When I tore my mount down and then put it back together I just snugged them up and tested the feel of the movement without the adjusting knobs in place. Set it to move smoothly with some resistance but not loose enough to move on it's own.

 Hi Thanks for your reply, and logically I would agree, and maybe it was just a coincidence but since I noticed an excessive amount of play when fully loaded at the latitude end of the mount and with the DEC on PHD2 all over the place; I thought this would be the answer, but more importantly than PHD2 graph, the end result of the image is almost as if a bird landed on the scope! and a big bird at that

My first thought to correct the DEC was to rebalance and double check the point of balance off mount with the scope (C8N from Celestron) on the bench and testing it that way. When I found the balance I took great care to ensure that it was 'on the point'. The RA, all though the RA appears fine, balance was now my next port of call and set this slightly East heavy. With both clutch levers released, all appears well and was reasonably pleased with the balance, with me being able to easily move the it with very little pressure on any part of the mount. However.... the image is still shockingly bad, and I've been imaging for a while now and this is the worst it's been. I've found that as generalisation majority of the issues I've found falls in to 2 distinct areas. User error and oh yes, user error! but this time I don't think it is, I think this is a bit more serious and am struggling to find the answer.

My AVX is 4 years old now, and almost destined for the bin!


Edited by Philkib, 18 April 2018 - 12:34 PM.


#11 Philkib

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Posted 18 April 2018 - 12:37 PM

DEC all over the place (actually periodic extreme jerks of the order of 40" sometimes) was a problem with *my* first AVX. Both Ed (Thomas) and then Celestron tried to fix it and ended up replacing the mount. The replacement has no issues. 

 

I would suggest returning these screws to approximately their pre-fiddling state, and then posting a PhD2 graph (preferably in a separate post). Don't fall into my mistake--I spent almost 4 months trying to 'fix' the unfixable. 

 

Thanks Stellios, I'm almost at the end of my tether on this one! and a new  Skywatcher EQ6-R PRO may well be on the cards.


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#12 Philkib

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Posted 20 April 2018 - 02:00 PM

 Hi
Can you help me please? I have an AVX and would like to have the thoughts on the community on an issue I have.
On the AVX there are 2 Orange decorative covers, under each one it covers a tension ring, which in turn one of them covers 3 grub screws. Now the question, how 'tight' should 1) the grub screws be? and 2) tension rings be?
Should they be VERY tight? moderately tight? or just nipped up? I suspect that it should just be nipped up and allow gravity to keep the mount in place when in use, but not sure.

Supplement question would be, how would these grub screws and tension rings effect the over all performance of the mount? as in, if they were set wrongly would that effect the performance with PHD2?

 

Thanks for taking the time to read this post!

 

Keeplookin' up!

 

Phil

Well... an update.

I should know better, my first thoughts, as a general rule, assume that there is a high probability of a case of user error when something goes wrong with your mount/scope/camera/focuser etc etc. However in this case I had checked everything, set-up, balance, polar alignment using ASPA, and what cemented my thoughts process was the fact that I had an excessive amount of 'play/movement' on the altitude part of the AVX. At the same time I'd connected PHD2 and after getting things up a running I found that my graphs were off the screen, they were all over the place, which left me scratching my head trying to work out what was going on here.

My first attempt to fix this was to try the Polar align within PHD2 to see if that would bring things back, well I've read so many reports about PHD2 having a great polar alignment routine, but nope... no joy with that and to be honest if anything, things were worse, if that was at all possible.

Weeks passed with the same results and being completely at a loss and at one point was all but going to negotiate with the good lady wife for a new mount. Now... that was not a particularly good prospect considering I've just spent a whack of money on another project, my chances of success for this year were slim to say the least!

Now you may start to wonder were this story is going, well, I was out again last night, with exactly the same results, hmmm have you ever seen a grown man the wrong side of fifty and closer to sixty sitting in my shed on the point of tears? that was me, my hobby was slipping away from me...

Then I stopped and thought of an inspirational speach I heard from Stephen Hawkins about looking up and not down at your feet, and try to make sense of what you see.

Then I had a thought, or maybe someone push the thought on to me smile.gif but the thought was along the lines of, there's nothing wrong with the mount, its perfect, it's just been hyper tuned by David Woods at  Dark frame Optics, the thing was working fine! so what has happened?

USER ERROR ALERT...

I'd ripped down the mount a fair few times and although loaded back on the same pier, as you know things don't go back in EXACTLY the same way. So when I started up PHD2 it was with the existing calibration information, and with time this was no longer a proper fit for the mount as I had changed and set up the mount so many times.

And this was the thought that came crashing into my head, "recalibrate PHD2, fool!" and I did, and guess what? it worked, perfectly! why had I not thought of this before?

no idea, I guess I got caught in the trap of thinking this must be a mechanical fault and not a user fault. However  I was running out of time last night as I had a very busy day at work today and had to get some sleep but I did manage a full 300 second exposure with ZERO star trails! delighted is an understatement!

no asking the wife for £1500 GBP for a new mount!

going out again tonight with the last of the astronomical dark and see if I can get some imaging done to keep my going over the summer.

 

Thanks for reading this ramble and clear skys to you!

 

 

Phil 


Edited by Philkib, 20 April 2018 - 02:06 PM.

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#13 Whuppy

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Posted 20 April 2018 - 03:33 PM

Good to hearsmile.gif , anytime you change anything in the optical train, even if just removing the guide camera you'll need to re-calibrate. Actually I re-calibrate almost every time and run the guide assistant to get of feel for the nights seeing, and yes, rebuilding your mount would definitely qualify as a reason to re-calibrate.


Edited by Whuppy, 20 April 2018 - 03:34 PM.

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#14 Stelios

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Posted 20 April 2018 - 04:43 PM

After being burned with my AVX, I bought a Mach1. On the second outing (the first went well, but I was just exploring the mount), I decided to get a perfect focus with my guide camera so I started imaging in pristine condition.

 

And of course, the mount went haywire. Guiding resulted in zig-zag stars. Strangely perfect zig-zags... at exactly 90 degrees. But I didn't notice this till later, I thought "such is my luck, that after getting the lemon AVX of all time, I got the lemon Mach1 of all time. Woe is me" frown.gif frown.gif frown.gif

 

Then I stopped guiding and took an unguided exposure--pretty decent. WTH? And then it occurred to me, that focusing the guide camera changed the orientation relative to the mount... Recalibrate fixed that, and the imaginary jinx flew away with a wink smile.gif -- or maybe a cackle lol.gif lol.gif lol.gif


Edited by Stelios, 20 April 2018 - 04:44 PM.

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