Celestron AVX service

[knobby]

Just spent 4 hours resurrecting my AVX mount, it had become so stuff in RA it just wouldn't track at all. Googled as much as I could find and used the http://rocketsparrow.blogspot.com/2017/01/how-i-made-better-celestron-avx.html?m=1 as a guide.

Decided to use a bearing as discussed in thread. I chose the https://simplybearings.co.uk/shop/p503131/32007-Premier-Budget-Metric-Single-Row-Taper-Roller-Bearing-35x62x18mm/product_info.html?backstep=1 as the dimensions were perfect ( almost perfect, bearing is 2mm too thick but works fine)

Cleaned all the gungy grease off and used thin layers of superlube.

It's so much smoother now and I can actually balance the mount.

Only problems I had were the 2 bolts that hold the RA and Dec assembly together stripped the mount ! Soft cast ally by the looks of it but there are 4 holes for 2 bolts (almost like Skywatcher knew 😂) and refitting the motor worm assembly is tedious to get backlash adjusted .

Can't wait to try it out.

Ps the new bearing wouldn't quite fit til I put the mount in the oven @ 80 degrees and the bearing in the freezer for 5 minutes.

Edited May 11, 2019 by knobby
Spelling

[knobby]

Well, it works 👍 guiding was a bit hit and miss but hopefully can be tweaked a bit ... Forgot to set up East heavy in my haste to see if it survived my surgery , Dec guiding spot on ( was reasonable before operation) Ra was up and down just above the 3 px mark on the graph.

[knobby]

Finally had a chance to play with it , no imaging just watching guiding.

Wonder if any PHD gurus would take a look as I'm not really sure what the numbers mean.

PA was excellent according to Sharpcap but not so in PHD2. Wonder if it's because Polaris just clears my roof so pretty unsettled air where I'm polar aligning.

The wonky calibration is (I'm guessing) due to the mount not knowing where it was pointing as only PA'd and no star alignment.

Very slightly East heavy using finder guider

Comments gratefully received.

 

PHD2_GuideLog_2019-06-08_224702.txt

Edited June 9, 2019 by knobby
Spelling

[Peter77]

Hello.

I do not have any answer to your guide problems

But this thread came up when searching for the AVX mount here. I bought a used one. Planned to use for imaging.

But as it behaves now, not even sure it is possible. For now I have a 115mm F7 triplet apo weighing 6.4kg (plus diagonal and EPs).

When observing, when going over 100x and up, an oscillation/vibration starts to be visible. At first I thought it was wind or hard ground that caused some kind of resonance. But today with almost no wind and setup on softer ground, this issue still present itself. Causing problems to come to a satisfying focus because the image wobbles. This happens while tracking. 

Almost impossible to get a sharp image of stars in high magnification. The problem was not there an earlier day when I just set the mount up and pointed to polaris. No tracking, didnt even turn the mount on. There was also some wind.

I removed covers over ra and dec to take a look at drive+wormwheel earlier but they were nicely tight so didn't touch anything.

Also relieved tensionring a little for ra axis. But still has some stickyness. Does not move very smoothly. Dec axis is fine though, tips over by itself when just unclutching and touch it with finger.

Not sure if this has helped though, maybe a little but just had a short session on Venus today, already hard to focus on. But did think I saw the same vibrations. Will have to have a longer session to evaluate if it did anything at all.

I notice the symptoms when both tracking lunar and tracking sidereal. And being new to eq mounts I am not sure which axis is causing the problem.

Been checking a few dissasembly pages and post, but havent quite plucked up the courage to go ahead. I am sure the mount could benefit from removal av the hard sticky overabundant factory grease, as well as checking for burrs and some light polishing. 

I've seen other complaints about this oscillation too. For now I just want to be able to observ with my mount and my new apo

And am beginning to regret that I didn't choose another mount.

Do anyone know what causes this problem and has any advice where to start?

As said, been checking some of this pages about dissasembly but feels that they're not covering every exact step.. so that scares me off a little.

I have allen keys, 1.27 to 1.5mm, and from 3 or 4mm up to 10mm. And pliers and sidecutters and lots of torx bits as well as screwbits both crossed and straight ones.

 

So tools are not a problem. But still would appreciate some advice..

Going to order a tube of superlube soon. As a start I will degrease and regrease the drives and wormwheel and see if it does any difference. But I suspect the problem comes from within the axis assemblies themselves.

Edited January 14, 2020 by Peter77

[knobby]

Mine was definitely better after stripping down, I had to do it as it was virtually useless after not being used for about 18 months.

Loads of info here https://www.cloudynights.com/topic/578878-celestron-avx-rebuild/