Correction signals hardly moving Ra&Dec.

[Ali]

I did a full cleaning/Lub and fine tuning for my Atlas eq-g..

All mechanical procedure gone smoothly and both axis are looks good..

I tried the mount under the sky and I really expect a very good guiding as I am sure about the rebuilding process..

Guiding looks fair (RMS 0.7 - 0.8) some times goes 0.9 or 1 ..

I bet It can do better but I couldn't make it..

My question is :

When you looking at Ra correction pulses they hardly move the Ra.. it takes 4 or 5 pulses to responds.. For Dec. I can handle that with backlash comp.

Log file is attached..

Any recommendations ? without stripping down again :(

Mount: Atlas eq-g ,belt mod 10 months ago and worked very well till it stopped while slewing and I decided to begin stripped down.

Scope : SW Esprit 100mm

OAG guiding with asi 290mm mini

Log File :

https://openphdguiding.org/logs/dl/PHD2_logs_5TXg.zip

Thanks.

Ali

[Steve]

Hi

Loosen the taper bearing at the base of RA.

HTH

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[Ali]

Thanks..

I set the taper bearing quite good ( nearer to loose than tightened ,, while the Ra axis  and the bearing are fit sturdy ) .

Ra axis is very smooth when you move it by hand. No any stiction.

Belt also in a good tightness condition ( not loose nor tight ),, I wondered if I give it a little tightness will be good ?! 

[Ali]

Backlash, GA , Calibration  results are attached .. Looks good for me .. What do you think.

[Bruce Waddington]

Hi Ali.  I see what you’re talking about although it’s unlikely to make a lot of difference to your imaging results.  This is some kind of mechanical behavior, it’s not guiding.  The possibilities that come to mind include:

 

1.      Some kind of static resistance in the RA system

2.      Possibly a weight imbalance in RA

3.      A need to increase the mount guide speed to 0.8x or 0.9x to help it push through the resistance

 

Good luck,

Bruce

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[علي الحواس‎]

Thanks Bruce.

Could you give a hint what is a "static resistance" please.

BR,,

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[bw_msgboard]

I was really thinking of any sort of impedance that might retard the ability of the RA axis to quickly accelerate above the sidereal rate.  Here's a section of the log I was looking at (RA in red):

 

 

These guide pulses were all to the west, meaning that guiding was trying to accelerate the RA tracking system to track the guide star.  I don't see this happening much when the guide pulses are east.  So it could be something like a bearing that can't move freely enough, gears that are meshed too tightly, etc - no way for me to guess, I don't have a mechanical engineering background.  This directional bias was why I also mentioned that a weight imbalance could be a problem.

 

Regards,

Bruce

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[Ali]

Thanks Bruce,

I recently solved ( thought its may solved ) 2 issues :

1- Ra Motor sound was not normal when slewing the mount with rate 6 speed, So, I decided to give a tiny release to the belt (untighten) .. Bang! sound normal now .

2- I re-mesh both Ra & Dec. worms .

Waiting now for the real test under the sky..

By the way, I have a suggestion to PHD2 developers, but its better to make a separate conversation .

BR,

Ali