Tuning guide EQ6 - common Dec issues

[Kiwi_Brad]

Hello everybody,

Such a great source of information here so thank you to everyone who shares their knowledge and I am after some more of anyone can help. 

I have a new EQ6 pro and the same issues that everyone else has with Dec backlash issues and saw tooth spikes randomly (not periodic). 
 

Excepting I can still do some Dec backlash adjustment to tune some of this out I am going to go full noise and replace the bearings, grease, and check for any anomalies. 
 

I will follow Astroblokes bearing replacement guide and tear down and have read a few others. 
 

What I want to know is if there is a guide for other areas or things to check along the way and parts I can or should clean up and polish. If I have it apart I want to tune and clean up anything that may help. 
 

Has  anyone tried the spring loaded worm gears for these? I saw them on an Australian site. 
 

The plan following that will be to get it back together and then concentrate on settings etc.   i don’t get any alerts from PHD2 but the backlash graph isn’t great and as I say guiding has plenty of corrections and saw tooth spikes randomly on Dec only. Guiding assistance gives me min move settings of .6-.9! RA is pretty good but still sets min move what I think is high at .3-.5. 
 

Cheers

[rnobleeddy]

I'd guess the belt mod might be the easiest solution? 

[scotty38]

19 minutes ago, rnobleeddy said:

I'd guess the belt mod might be the easiest solution? 

What’s the belt mod for this as it’s belt driven anyway? Asking as I have an az-eq6…..

Edited October 26, 2021 by scotty38

[Kiwi_Brad]

45 minutes ago, rnobleeddy said:

I'd guess the belt mod might be the easiest solution? 

Thanks

It’s an EQ6-r it’s already belt driven. 

[rnobleeddy]

38 minutes ago, Kiwi_Brad said:

Thanks

It’s an EQ6-r it’s already belt driven. 

Sorry - thought you had the older version. In that case I guess it's just a case of tuning, but I'll let someone else with more experience comment futher!

[newbie alert]

23 hours ago, Kiwi_Brad said:

Hello everybody,

Such a great source of information here so thank you to everyone who shares their knowledge and I am after some more of anyone can help. 

I have a new EQ6 pro and the same issues that everyone else has with Dec backlash issues and saw tooth spikes randomly (not periodic). 
 

Excepting I can still do some Dec backlash adjustment to tune some of this out I am going to go full noise and replace the bearings, grease, and check for any anomalies. 
 

I will follow Astroblokes bearing replacement guide and tear down and have read a few others. 
 

What I want to know is if there is a guide for other areas or things to check along the way and parts I can or should clean up and polish. If I have it apart I want to tune and clean up anything that may help. 
 

Has  anyone tried the spring loaded worm gears for these? I saw them on an Australian site. 
 

The plan following that will be to get it back together and then concentrate on settings etc.   i don’t get any alerts from PHD2 but the backlash graph isn’t great and as I say guiding has plenty of corrections and saw tooth spikes randomly on Dec only. Guiding assistance gives me min move settings of .6-.9! RA is pretty good but still sets min move what I think is high at .3-.5. 
 

Cheers

Before you take it apart you need to cross off all the  other avenues first  such as balance, calibration, PA , shaft locking ring over tightened, belt over tension,  pulley oscilaton, too short a camera loop etc..

Have you got  a screenshot of your guiding?

A friend's eq6 r pro guides fantastic straight out of the box, no need to potentially introduce other issues.. taking it apart should be a last resort after you've eliminated all the other options ,and certainly not if it's within it's warrenty as opening it up voids it..

[Kiwi_Brad]

6 hours ago, newbie alert said:

Before you take it apart you need to cross off all the  other avenues first  such as balance, calibration, PA , shaft locking ring over tightened, belt over tension,  pulley oscilaton, too short a camera loop etc..

Have you got  a screenshot of your guiding?

A friend's eq6 r pro guides fantastic straight out of the box, no need to potentially introduce other issues.. taking it apart should be a last resort after you've eliminated all the other options ,and certainly not if it's within it's warrenty as opening it up voids it..

Yeah thanks. I’m still in the tuning phase. I don’t have the mount computer on at the moment. 
 

i spent today re tuning Dec backlash. The shaft end cap was def too tight and on d I backed that off enough so it was just holding the roller bearing etc all in place with no play the second axis was much easier to accurately balance. 
 

I’m pretty sure balance wasn’t right it as accurate as it could be but now it should be much better.  I also redid the back lash which needed some work. 
 

I will try this the next clear night. That shaft end cap issue straight of the box could be a regular occurrence. 
 

Thanks for your help team. 

[Kiwi_Brad]

Can someone tell me if the min motion settings being recommended at .5 etc and quite high would be to do with switching to an OAG at 650mm?  I’m presuming it is and hasn’t thought about that. 
 

i did set up a new PHD2 profile as I switched over. 
 

Thanks

[michael8554]

Quite possibly.

But you need to look at a GuideLog with the Log Viewer, to see how many arcsecs the 0.50 setting actually equates to.

Michael

 

 

[Starflyer]

5 hours ago, Kiwi_Brad said:

Can someone tell me if the min motion settings being recommended at .5 etc and quite high would be to do with switching to an OAG at 650mm?  I’m presuming it is and hasn’t thought about that. 
 

i did set up a new PHD2 profile as I switched over. 
 

Thanks

You can calculate your own minmo value to check what PHD2 is suggesting, though I find what it suggests is best.

https://www.myastroscience.com/minmoveinphd

[newbie alert]

6 hours ago, Kiwi_Brad said:

Can someone tell me if the min motion settings being recommended at .5 etc and quite high would be to do with switching to an OAG at 650mm?  I’m presuming it is and hasn’t thought about that. 
 

i did set up a new PHD2 profile as I switched over. 
 

Thanks

Run the guide assistant and apply the  recommended settings 

[michael8554]

An interesting link Starflyer,  I will digest that TAE theory.

So Brad, a MinMo of 0.50 pixels will be equivalent to this many arcsecs:

Your guide image scale in arcsecs/pixel  x  0.50 pixels.

Michael

 

[Kiwi_Brad]

46 minutes ago, michael8554 said:

An interesting link Starflyer,  I will digest that TAE theory.

So Brad, a MinMo of 0.50 pixels will be equivalent to this many arcsecs:

Your guide image scale in arcsecs/pixel  x  0.50 pixels.

Michael

 

Perfect thank you Michael. That’s fairly obvious isn’t it but exactly what I wanted. 
 

My scales and min move are all good then. Just higher than I am use to seeing with guide scope. 
 

I always run guide assistant for a full work cycle and apply the recommendations. It’s very rare I try to be smarter than computer software! 
 

Thanks again. 
 

i will try to dig out some logs etc from my last run and then when I get out again after loosening off the end shaft cap as I have seen other guide graphs identical to mine on here. 

[Kiwi_Brad]

Hello again,

 

The Dec seems to be MUCH better with the end shaft cap loosened and certainly balance is much better now. 
 

I think overall the mount is probably doing what it is supposed to although not great it’s under 1” mostly so I guess I can’t complain?

 

I was just wondering if someone with a bit of knowledge could take a quick look at a log from last night. Was perfect conditions so nothing else to blame.  At times where I calibrated it would settle to .5-.6” which I was happy. Still getting some spikes in RA. 
 

There is every chance I could do things better / differently and improve but I don’t know what I’m doing wrong unless someone tells me. 

 

Thanks very much for anyones times in advance! If anything else is needed please let me know. I’m planning on getting out again in a few hours. 
 

Cheers 🤙🏿

PHD2_GuideLog_2021-11-07_201900.txt

[michael8554]

Hi Brad

Calibration looked good. The steps were slightly bunched up into pairs, indicating some stiction, but this didn't appear to affect guiding.

PA was good, 1.1arcmins.

You guided for 50 minutes, THEN ran Guide Assistant.

A shame, because then you mostly only made runs too short to see the trends with the suggested settings.

Best to Cal, then GA, then guide.

Your 9 minute session had good figures, RA = 0.58 arcsecs, Dec = 0.66, these should yield round stars.

With your final 7 minute run you slowed exposure from 2.5 to 3 seconds, and enabled Multistar.

MultiStar tries to compensate for Seeing, so exposures can be increased to as fast as 1 second, not decreased to 3 seconds.

At the end of your final run, RA and Dec shot off on their own and the guide star was lost.

If that wasn't you "shutting down", then there was probably a cable snag.

Michael

 

 

[Kiwi_Brad]

On 09/11/2021 at 00:14, michael8554 said:

Hi Brad

Calibration looked good. The steps were slightly bunched up into pairs, indicating some stiction, but this didn't appear to affect guiding.

PA was good, 1.1arcmins.

You guided for 50 minutes, THEN ran Guide Assistant.

A shame, because then you mostly only made runs too short to see the trends with the suggested settings.

Best to Cal, then GA, then guide.

Your 9 minute session had good figures, RA = 0.58 arcsecs, Dec = 0.66, these should yield round stars.

With your final 7 minute run you slowed exposure from 2.5 to 3 seconds, and enabled Multistar.

MultiStar tries to compensate for Seeing, so exposures can be increased to as fast as 1 second, not decreased to 3 seconds.

At the end of your final run, RA and Dec shot off on their own and the guide star was lost.

If that wasn't you "shutting down", then there was probably a cable snag.

Michael

 

 

Thanks Michael

Good to know I am not doing anything weird contributing to errors. 
 

Ran GA after that time because I was recording PEC Curve. Which was great except one patch of vertical movement so I scrapped it.  Clearly something going on there. 
 

The multi star guide is odd as I always have that on and didn’t touch it at all. It never seems to work with OAG even if I can see multiple stars. Is there a way to force it? 
 

The following nights numbers were much worse which was frustrating as I have no idea why. I’ll get a couple of hours tonight to just go through it again. 
 

Can someone confirm for calibration what RA and Dec I should be looking to do this at. I thought it was easy or west and low to horizon? 
 

Thanks

[newbie alert]

5 hours ago, Kiwi_Brad said:

Thanks Michael

Good to know I am not doing anything weird contributing to errors. 
 

Ran GA after that time because I was recording PEC Curve. Which was great except one patch of vertical movement so I scrapped it.  Clearly something going on there. 
 

The multi star guide is odd as I always have that on and didn’t touch it at all. It never seems to work with OAG even if I can see multiple stars. Is there a way to force it? 
 

The following nights numbers were much worse which was frustrating as I have no idea why. I’ll get a couple of hours tonight to just go through it again. 
 

Can someone confirm for calibration what RA and Dec I should be looking to do this at. I thought it was easy or west and low to horizon? 
 

Thanks

For pulse guiding In the northern hemisphere we should be calibrating on the equator ( so pointing south and on DEC 0/ meridian intersection.... 

For a oag the .5 camera loop might be far too short.. I use 2- 3 sec loop but I'm using a sct.

With multi star,  click the loop button, click the button to the right of it and it will pick it's own stars, then press guide button.. 

[Kiwi_Brad]

1 hour ago, newbie alert said:

For pulse guiding In the northern hemisphere we should be calibrating on the equator ( so pointing south and on DEC 0/ meridian intersection.... 

For a oag the .5 camera loop might be far too short.. I use 2- 3 sec loop but I'm using a sct.

With multi star,  click the loop button, click the button to the right of it and it will pick it's own stars, then press guide button.. 

sweet thanks for that that’s where I calibrate now so all good. 
 

I always let PHD pick the guide star it just never picks multistars now for some reason. 
 

thanks for the info.  Always appreciated. 

[michael8554]

Hi Brad

I'd forgotten you were OAG.

With a small prism and a small guidecam sensor it can be difficult to discern enough stars for MultiStar to work.

So longer exposures were the right choice after all.

10 hours ago, Kiwi_Brad said:

Ran GA after that time because I was recording PEC Curve. Which was great except one patch of vertical movement so I scrapped it.  Clearly something going on there. 
 

Don't forget it's RA info you're gathering for PEC, not Dec.

Michael

[Kiwi_Brad]

Thanks Michael.  Yes it was on the finished pec curve was all very nice except one patch. Has done it twice I will try once more and post an image of it. I am guessing it’s binding but I don’t identify it on slew so may need some help. 
 

I have found a few settings in PHD which were wrong including saying I have as calibrating at Dec -60 so maybe those few little changes will help also. 
 

RA is still very tight. I would say there is some level of stiction there. Does anyone know how to help that like that end shaft cap in DEC which was over tightened. 

Thanks 
 

 

[Kiwi_Brad]

I have now slackened off slightly the nut against the roller bearing in RA after have trouble balancing and this has significantly helped that process.  Slight adjustments on the meshing of both axis and using a ammeter confirmed there is no binding or backlash. 
 

It will be interesting to see how it goes now being a brand new mount and have those minor issues before like many other if these easy tweaks fix it. 
 

Cheers

[Kiwi_Brad]

Hi everybody. Just a quick updated. The above methods fix most of the issues for this mount for me. The end cap nut was far to tight and a quick work adjustment using a voltmeter to pick out high spots worked well.   
 

it is consistent now but still not great numbers. Comfortable around .7” mark but does drop right down to .5. This just get ruined by large erratic spikes. 
 

Short of pulling it apart to rebuild it (still under warranty so won’t do that yet) seems to be the best I can get out of this iteration of the mount. 
 

Any suggestions welcome. 
 

Cheers

[bottletopburly]

9 hours ago, Kiwi_Brad said:

Hi everybody. Just a quick updated. The above methods fix most of the issues for this mount for me. The end cap nut was far to tight and a quick work adjustment using a voltmeter to pick out high spots worked well.   
 

it is consistent now but still not great numbers. Comfortable around .7” mark but does drop right down to .5. This just get ruined by large erratic spikes. 
 

Short of pulling it apart to rebuild it (still under warranty so won’t do that yet) seems to be the best I can get out of this iteration of the mount. 
 

Any suggestions welcome. 
 

Cheers

Try guiding in phd2 multi star mode and 1.5sec exposure ,what  rate is ra/Dec setting in pulse guide settings default is 0.10 

[Kiwi_Brad]

14 hours ago, bottletopburly said:

Try guiding in phd2 multi star mode and 1.5sec exposure ,what  rate is ra/Dec setting in pulse guide settings default is 0.10 

Pulse guides are 0.70 I usually switch up exposure on guiding from 1.5-3 depending on conditions. 
 

I had excellent conditions last night but guiding would still blow out to 1.1 in some spots of the sky.  Bad moon glow as well. Was guiding better during all 53 minutes of dark sky.   Just wish the mount was a bit more consistent.