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Declination Backlash in my Eq6R Pro mount

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#1 Nathanet

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Posted 22 October 2019 - 08:47 PM

        While I'm still getting fairly good results in PHD2, every time I run the guiding assistant it tells me there is a backlash reading between 11 and up to 20 seconds. (11000 to 20000 ms)  This backlash seems to be consistent throughout the evening so I don't  think it is temperature related.  I feel as though I am able to balance my rig correctly and, have my cables managed so there are no snags or anything like that.   

        My question is how should I address the problem,  Should I do the worm adjustment as shown on astrobaby.  I've seen a lot of people post about doing it to correct the backlash in declination.  I bought the mount new and have had it less than a year and was wary about opening it up.  However, if this is something I would have to do eventually I might as well learn to do it as I plan to use the mount till it dies.  Ill include the debug and guide logs from a couple of nights if that'll help.  Any suggestions would be welcome. Attached File  PHD2_DebugLog_2019-10-22_170356.txt   16.58KB   10 downloads



#2 jimr2

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Posted 22 October 2019 - 11:04 PM

Nathan,

There was a post just the other day--20 Oct--about correcting backlash problems in this mount. It was posted by "frito", again on 20 Oct, with the title "Some info for those that have an EQ6-R that has developed backlash...". It was posted under "Mounts" in CN forums. See that for starters....

-jim-
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#3 jimr2

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Posted 23 October 2019 - 05:07 PM

Nathan,

Hi again--did you find that previous CN post regarding backlash in Skywatcher mounts? If so, hope that was your problem and that "fix" took care of it?

I guess I'm just a bit dismayed that so many people are having backlash issues with the EQ6-R mount after only having owned them for about 1-year. I was about to pull the trigger on one of these mounts, until I started seeing the posts about people having problems with theirs, on CN posts here within the last 2-3 weeks. So now I'm not so sure I want to go with the EQ6-R Pro anymore or not. Just out of curiosity, how do you like the mount otherwise? And do you use your for AP any? If I don't go ahead with purchasing one of these mounts, I'm not sure what else to get, that's still in it's price range, and has all the features this one has. Anyhow, if you'd care to let me know how you like the mount otherwise, and pros or cons about it, etc., I'd appreciate it--thanks! (You can just post your comments here on CN, or PM me....)

And again, hope the belt tension fix too care of your issues....

-jim r-

#4 MikeECha

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Posted 23 October 2019 - 09:05 PM

        While I'm still getting fairly good results in PHD2, every time I run the guiding assistant it tells me there is a backlash reading between 11 and up to 20 seconds. (11000 to 20000 ms)  This backlash seems to be consistent throughout the evening so I don't  think it is temperature related.  I feel as though I am able to balance my rig correctly and, have my cables managed so there are no snags or anything like that.   

        My question is how should I address the problem,  Should I do the worm adjustment as shown on astrobaby.  I've seen a lot of people post about doing it to correct the backlash in declination.  I bought the mount new and have had it less than a year and was wary about opening it up.  However, if this is something I would have to do eventually I might as well learn to do it as I plan to use the mount till it dies.  Ill include the debug and guide logs from a couple of nights if that'll help.  Any suggestions would be welcome. attachicon.gif PHD2_DebugLog_2019-10-22_170356.txt

If I were you, I would take the guide assistant with a big grain of salt.  In my case, the GA has reported big polar aligment errors when I know that SharpCap shows "excellent" aligment with less than 10 arc-sec on both RA and DEC. I trust SC because I can see the trace of Polaris perfectly concentric with the circles on the screen as I rotate the RA axis.

 

How is your DEC guiding? If it is still good you know PHD GA is "misinformed".

 

I have also seen the GA suggest MIMOs that when applied make guiding worst. Since I now have a good understanding how capable my mount is under different seeing conditions, I have stopped acepting Mimos from PHD2. I change them myself by observing my mount behaviour.

 

Do you feel any play on the DEC axis if you softly shake the saddle? Check that the round thing where the CW bar comes out did not get a little loose with use and time. That piece is the retaining nut for the DEC thrust bearing that is just behind it. If loose, it my allow the bearing to drop a bit out of its housing by gravity and it may be the cause of your problem.

 

When troubleshooting, I like to clear the low hanging fruits firt. And having seen how the worm is installed, if it once worked fine, I doubt it is the problem now. 

 

Keep posting updates if you can. I would be interested to see what the problem is.

 

Thanks


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#5 Nathanet

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Posted 24 October 2019 - 03:29 PM

Hey Jim,

I did find the article thanks again!! I a have not opened up the mount yet as I said in the post I'm getting good enough results (for me anyhow) right now. Also I live in the San Francisco Bay Area and we are having clear night after clear night so Im gonna take advantage of the great weather before the winter and fog come back. My total RMS error generally fluctuates between 6 to a little over 1.0 so and I feel I'm still getting pin point stars. The only time the backlash comes up is in the Calibration and Guide assistant when it measures the mount's backlash.

My set up is: Eq6r Pro

Williams Optic Zenithstar 73

ZWO 1600mm pro

Orion Starshoot guide cam Orion 50mm guidescope

 

I realize this is a very forgiving set up and don't know how it'd handle a scope with a greater focal length. As for the mount I do like it alot. This is coming from the perspective of this being my first Equatorial mount and Ive been doing astrophotography for less than a year. My mount is one iteration behind the current I believe as they've now put a usb port on the mount itself where as mine is on the hand controller. I think if you look up any mount on CN youre going to find that there are criticisms of said mount. For all the criticisms of the Eq6 r I also see alot praise of the mount as a work horse for the 1500 price tag. Most mounts I've looked up I've seen folks having to deal with backlash. Its one area I find odd that (at least from what I've seen) theres no standard allowance for it that would qualify as either being a good mount or one that should be returned. All in all if your wavering on pulling the trigger, I guess you do have to consider the backlash issue and whether or not your going to deal with it. I don't see any mount in the 1500 dollar price range where people aren't having backlash. I shot the Elephants Trunk last night. They were all 5 minute exposures and for me the stars seem tight.

Thanks again,

Nathan

 

I'll also update and post when I do go into the mount.

Untitled-1.jpg



#6 Nathanet

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Posted 24 October 2019 - 04:38 PM

I did check the saddle and I'll check the area where the cw shaft drops out.  I haven't noticed any play.  I have also seen the guiding assistant suggest a bad polar align when I know its spot on but that's actually rare for me.  Where I notice the backlash is in it's measurement of it.  In guiding sometimes it takes a minute for it to pull it south.  For the most part it's not the biggest deal as I originally posted I think my results are good and the RMS error (not the end all be all judge of good guiding) is in the decent zone.  




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