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Need help with Celestron AVX!

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#1 JPDucky

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Posted 15 January 2014 - 09:30 PM

I have a celestron AVX and when I try and polar align it the Azimuth axis feels loose. And by loose I mean if I push it, it can move like 1/4 of a degree even if the adjustment knobs are tightened all the way. Any ideas? -Also, does anyone recommend an illuminated reticule?

#2 Mr Greybush

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Posted 16 January 2014 - 12:01 AM

check the alignment peg on the tripod to make sure its tight. A 12mm reticule from Celestron works fine some co's have 5mm's but my eye's can't use them.

#3 schluterdude

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Posted 16 January 2014 - 10:09 AM

Also check that the center mounting bolt is tight, and it's really not just rocking around.

#4 John608

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Posted 16 January 2014 - 01:26 PM

Hi JP,
In addition to John L.'s suggestion, make sure the bolt that holds the head on the tripod is tight, if it is loose the head will wobble in azimuth. As for reticles eyepieces yes they are worthwhile for alignment, 12mm or so is a popular focal length. Orion has a centering eyepiece with a of about 20mm fl with a 70 degree FOV that might work very well for aligning. Good Luck!

John G.

#5 JPDucky

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Posted 17 January 2014 - 03:14 PM

Thanks!

#6 JPDucky

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Posted 17 January 2014 - 05:21 PM

Well, I just got home to take a look at it, and it doesn't matter how tight I screw it down, the mount still has to use the screws to make it turn, and because of that it wiggles. It is bolted down on the bottom and tightened in the front with the adjusters, but that leaves the back end to wiggle. Any suggestions?

#7 dragonslayer1

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Posted 17 January 2014 - 05:23 PM

take it apart and reassemble it, Kasey

#8 TCW

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Posted 17 January 2014 - 06:48 PM

If by some chance you have the legs extended all the way it will be quite wobbly. Retract them several inches and you will see a big improvement. ;)

#9 JPDucky

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Posted 17 January 2014 - 07:57 PM

I have done both, with no satisfactory conclusion.

#10 schluterdude

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Posted 17 January 2014 - 08:03 PM

Once you are polar aligned, lock it down.

You are right, it will wobble when the center fixing bolt is loose. The adjustment knobs aren't meant to fix it in place. Line it up, tighten the fixing bolt.

#11 TCW

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Posted 17 January 2014 - 08:23 PM

Do you have the leg spreader/eyepiece holder installed and tightened up? Make sure the legs are fully spread. Other than that go over every nut, bolt and connection and make sure something is not loose. I just got my AVX and I am impressed with how solid it is. :jump:

#12 JPDucky

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Posted 18 January 2014 - 04:18 PM

I've tightened down everything but it still is shaky.

#13 rdandrea

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Posted 18 January 2014 - 04:35 PM

I've tightened down everything but it still is shaky.


Did you check to see if the azimuth pag is tight as suggested above? The azimuth adjusting screws press on a peg that is screwed into the mount base. If the scope still moves with both the azimuth adjusting screws tight against the peg, it either has to be a loose center bolt or a loose azimuth peg. Those are really the only degrees of freedom. If you've tightened the center bolt, that only leaves the azimuth peg.

#14 schluterdude

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Posted 18 January 2014 - 04:38 PM

Are there any burrs on the base plate, or the head bottom?

Is the fixing bolt bottoming out before it has a chance to clamp?

Check the alignment pin again....

Perhaps it is time to break out a dial indicator and start looking around to find out exactly where the play is coming from...

Can you post a pic of where you think the play is? Can you see the gap in the mounting surface?

Are you only seeing it when looking through the scope? Are you tightening the clutches sufficiently? The dovetail clamp?

#15 JPDucky

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Posted 18 January 2014 - 04:38 PM

The movement is on the opposite side of the peg. It's tight as it will ever be, and so is the screw on to the base. Mechanically, this makes no sense to me.

#16 schluterdude

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Posted 18 January 2014 - 04:40 PM

So, 180 degrees?

REALLY stupid question, but you are sure you have the head seated on the baseplate correctly?

#17 JPDucky

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Posted 18 January 2014 - 04:45 PM

I am. I'll fiddle underneath the head again when I get home, but tightened down with force of God it still moves. I can see the movement easily just by looking at the back of the scope. And yes, the movement is 180 degrees opposite the peg.

#18 TCW

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Posted 18 January 2014 - 05:25 PM

Perhaps another set of eyes might help?

#19 FacEngRet

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Posted 18 January 2014 - 06:54 PM

My first AVX mount had this same movement caused by a sloppy fit between the bottom of the mount and the socket in the tripod. I put one layer of aluminum foil tape around the hub on the bottom of the mount to eliminate the gap. My second AVX is a much tighter fit and did not need the tape.

#20 JPDucky

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Posted 20 January 2014 - 06:41 PM

Here's a video.

http://www.youtube.c...eature=youtu.be

I flipped the adjustment peg around to the other side and the problem persists.

#21 FacEngRet

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Posted 20 January 2014 - 07:19 PM

Check to see if the alignment peg is too high and not allowing the mount to seat properly on the tripod. You can remove the peg and then install the mount on the tripod to see if it seats better.

#22 JPDucky

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Posted 20 January 2014 - 08:01 PM

I just tried that, It was like pouring gasoline on a fire. It gave it free range of motion.

#23 LateViewer

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Posted 21 January 2014 - 07:46 AM

I don't have an answer but I loved your comment at the end. It is quite a problem.

#24 Patrick

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Posted 21 January 2014 - 09:27 AM

I just tried that, It was like pouring gasoline on a fire. It gave it free range of motion.


That makes it pretty obvious that your center bolt is not clamping the mount head to the tripod with enough (or any) force. If it were you would not be able to budge the mount head. Something is preventing the center bolt from clamping properly. Even if the center bolt seems tight it's not clamping which means something is bottoming out before the center bolt can clamp the mount head to the tripod base. You should be getting a good clamp force on the center bolt whether the spreader bar is attached or not.

Take some PICTURES! That would really help us see what's going on. It's not that complicated and should be an easy fix what ever it is.

Patrick

#25 Patrick

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Posted 21 January 2014 - 09:45 AM

PS...I looked at your video but it doesn't provide enough information. Could you take a close up picture of the tripod head without the mount on it and with the center bolt protruding up? Also, could you take a close up picture of the bottom of the mount head to see if there are any burrs or protrusion that are causing the mount head to not rest on the tripod head. Also, measure the height of the center bolt protrusion and the depth of the counterbore in the tripod head to make sure the center bolt protrusion on the mount head is not bottoming out before the mount head comes to rest on the tripod head.

One other potential problem area is that the threads on the center bolt may be bottoming out in the mount head. This could happen if the hole is not deep enough. Try putting a washer between the bottom of the tripod head where the center bolt clamps on the underside of the tripod and the center bolt 'stop'. To do this you will need to unthread the center bolt from tripod head, add the washer and screw it back into the tripod head.

Patrick






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