Eq6r-pro cold weather issue

[Wonderweb]

Hi all. 

Just wondered if anyone has had an issue with their eq6r-pro in cold weather. 

I recently replaced the bearings and belts on the mount and spent alot of time tuning out the worm gear back lash. When I had finished both axis did full rotations in both directions with no binding. Following this my guiding was between 0.3 and 0.6 total rms.

Last night while imaging, the temperature dropped quite sharply from around 0 degrees to minus 4 and my guiding really suffered and I couldn't get better than around 1.1 total rms. 

Have I sailed too close to the wind with the backlash tuning and as the temperature dropped and the steel contracted it has started to bind? 

I will check without a scope on my mount and do full rotations when it drops really cold again but just wondered if anyone has had the same experience 

Thanks

Darren 

[rnobleeddy]

I have an older EQ6 and it appeared to have some stiction visible in PHD2 graphs this week. I wondered the same thing, but then came to the conclusion that I'd expect the opposite effect - if the worm gear is too close, then surely colder metal contracts and it's less likely to bind?

[ONIKKINEN]

I dont think its a thermal binding issue since the drop in temperature was only 4 degrees. 10-20 degrees, maybe, but definitely not 4 degrees unless you were a micron off the ideal bakclash setting.

Something else is likely the culprit and what that is would be difficult to guess. Many reasons, too many to guess from. If you post a guide log here someone may be able to take a better guess as to why it got worse.

[wimvb]

If the temperature drops suddenly, there may very well be some moisture in the air that is condensating, ie clouds, dew or frost, which can affect guiding.

Have a look at changes in DEC vs changes in RA. With good balance and decent polar alignment, DEC rms can be used as an indicator for seeing. If all corrections are one sided, PA or imbalance cause a high RMS. Stiction is most often clearly visible in the guide graph. Random moves in DEC are often caused by atmospheric effects. Those you can do very little about, other than to increase MinMo and/ or decrease guide rate/aggressiveness.

Edited January 19, 2023 by wimvb

[newbie alert]

Did you set the worm whist inside, say for instance its 20 degrees and then using it at say -4 that could be enough depending on how finely you set it, did you check again after tightening the worm bolts, I'd also have it loaded as that's how it's going to be used

You could have binding issues from how tight the shafts locking nut is, many have experienced that from being factory set..

[jpoulette]

This is interesting. I'm still in the process in selecting a mount for imaging and this was my first choice (so far). In New England -9 to -6 (15-20F) is very common.

I see the EQ6R has no published temperature operating range, which is puzzling. The iOptron CEM40 has published -10 to +40C (14 to 104 F) operating.

Would anyone have any other data on the Sky-Watcher line? 😀

Jim

Edited January 19, 2023 by jpoulette

[wimvb]

1 minute ago, jpoulette said:

Would anyone have any other data on the Sky-Watcher line?

I use my AZ-EQ6  at -20 C with no problems to speak of. A friend has his EQ6-R  2 meters from mine, also running smooth.

[Wonderweb]

4 hours ago, newbie alert said:

Did you set the worm whist inside, say for instance its 20 degrees and then using it at say -4 that could be enough depending on how finely you set it, did you check again after tightening the worm bolts, I'd also have it loaded as that's how it's going to be used

You could have binding issues from how tight the shafts locking nut is, many have experienced that from being factory set..

I did set the worm gear inside the house (so probably around 20 degrees). I also had the mount empty (no scope or counterweights) when I did the full rotations to check for binding. I did spend alot of time trying to tune the backlash as fine as I could get it. The shaft lock nuts are set as loose as possible without any lateral movement within the taper roller bearings. When I slacken the clutches off the scope will drift towards an out of balance position of its own accord. I dont need to set it in motion. 

[Wonderweb]

6 minutes ago, jpoulette said:

This is interesting. I'm still in the process in selecting a mount for imaging and this was my first choice (so far). In New England -9 to -6 (15-20F) is very common.

I see the EQ6R has no published temperature operating range, which is puzzling. The iOptron CEM40 has published -10 to +40C (14 to 104 F) operating.

Would anyone have any other data on the Sky-Watcher line? 😀

Jim

Have a look at northern panorama on YouTube. Its a guy in Swedish lapland who regularly images down to minus 25 with his eq6r-pro and it seems like the last thing that ever gives him problems is his mount. Thats why I'd be so surprised if my issue is temperature related. 

[Wonderweb]

Maybe its better to let phd2 deal with a bit of backlash than have it fight binding?? 

Edited January 19, 2023 by Wonderweb

[newbie alert]

1 hour ago, Wonderweb said:

Maybe its better to let phd2 deal with a bit of backlash than have it fight binding?? 

Before you adjust things it may well just be down to atmospheric conditions.. thin high cloud isn't always seen by the naked eye but it will have an effect of guiding, did you notice the FWHM or hfd of the guide star a higher figure than normal.. maybe worth another trial before you adjust.. only adjusting if you really need to

[rnobleeddy]

I'm no guiding expert, but I'd imagine the difference between binding and other causes of bad guiding is usually apparent from the PHD2 graph. On my mount, when I get binding in the DEC axis it looks very different to bad tracking due to cloud, wind etc.

[Starflyer]

I had a night off absolutely dire seeing on Wednesday, I thought the same as you; something must be wrong.  After rebalancing twice and making sure everything was tight I noticed the FWHM was really high, autofocus was really struggling and I packed up, I've never seen it so bad.  I set up last night and everything was back to normal, I know clear skies are in very short supply but don't be too quick to tinker with a working setup.

It's probably not your mount but poor atmospherics, that said, it's best to set up your worm backlash in the average temp you'll use the mount at.  I'd say ~ 10°C for the UK, if you set it up too cold it'll bind in the summer.

[DSviewer]

Good to know is it worth some sort of thermal covering 

[Stefan73]

8 minutes ago, DSviewer said:

Good to know is it worth some sort of thermal covering 

I haven't bothered for cold in the UK.

When it was recently down to -7C it was some of the best guiding I've seen on my Eq6-R (and I've not fiddled with it at all).  Like others, I'm pretty sure that was just down to seeing as I've had much worse on slightly warmer nights where you could see a bit of high cloud.

I'd be far more worried about temperature and thermal coverings if I was doing solar observation in full on summer sun on a hot day.