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Guiding Problem in Dec-Axis with EQ-5 SynScan

astrophotography beginner mount
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#1 mwr

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Posted 19 May 2019 - 11:59 AM

According to the guiding graph (see PHD2 log viewer graph below) I have a severe problem which can be assigned to declination backlash and static friction. I have already tried to adjust the gear in order to minimize backlash (obviously with limited success). Is there anything else I could try to overcome the static friction problem? 

 

declination backlash and static friction; EQ-5 SynScan

 



#2 oshimitsu

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Posted 19 May 2019 - 01:12 PM

I'm no expert but it looks like it's binding which is not something you want to leave uncorrected. Make sure your check the gear mesh throughout the entire worm gear cycle as there will be high and low spots. You want to set the mesh to where it has a tiny bit of breathing room at it's highest point. Hopefully someone with a little more knowledge will chime in


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#3 sg6

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Posted 19 May 2019 - 02:50 PM

This is getting weird. Yesterday I caught sight of hyper tuning an EQ5, I have an EQ5 and wasn't sure what could be done. It was on the Darkstar site who belt drive EQ6's etc. No belt drive for an EQ5 seems not possible.

 

Right to maybe relevant bits.

The Dec worm drive is held by 2 O rings APPARENTLY. Now O-rings to me mean rubber, but dimensions seem odd for rubber O-rings. I suppose there is a chance that this has changed since the initial question was asked think I read 2010, basiclly the O rings are poor and die.

 

Darkstar do a tune which is basically all the change assorted EQ5 bearings and fit alternative somethings. Including to the Dec worm.

 

Reading the Dec worm is the one to look at. The tuning to the other items is replacing one bearing with another, maybe better one but nothing significantly different.

 

The Dec is a problem, putting new O rings in is pointless, so they fit a bearing (?).

However further reading the worm bearing hole is 11.3mm dia, the worm shaft is 6mm. There is no corresponding bearing with that outer diameter.

 

Someone on Iceinspace took an 11mm/6mm bearing wrapped insulating tape and pushed it all back in. They said it did a good job. Maybe better then a worn perished O ring.

 

Darkstar mention a ceramic bearing (?). But I do not know if this implies they take the worm bracket and over bore it to 12mm, or if the ceramic bearing is like a bronze bush, and produced to 11.3mm.

 

After about 4 or 5 sites I decided that should I ever need or want to do anything I would likely get a small piece of bronze bush/bearing material at 12mm and have it turned down to 11.3mm and have a 6mm central hole bored. Then put the new assembly back in. And so have bronze bushs as the bearing material.

 

Not sure if Darkstar would modify just the Dec worm, as that way you take the bracket out, with worm. Wrap it up, box it and send them. But there is no mention of such - could be worth asking, as it would be a much nicer and simpler upgrade. Even if not a full tune.


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#4 Spoonsize

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Posted 19 May 2019 - 05:25 PM

Rowan Astronomy for belt driving EQ5
There are instructions online to take the 5 apart, clean it, put it back together with better grease, adjust it and just maybe all that would lead to better guiding.
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#5 mwr

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Posted 20 May 2019 - 06:12 AM

Rowan Astronomy for belt driving EQ5
There are instructions online to take the 5 apart, clean it, put it back together with better grease, adjust it and just maybe all that would lead to better guiding.

Thanks for the hints!

 

However, it seems that Rowan Astronomy does offer a belt kit only for the HEQ5. Could you share the links for the online instructions to take the EQ5 apart?

 

Additionally, I will test if imbalancing the mount in Dec-axis has an positive effect (as suggested by Michael Covington: http://www.covington...tes2/index.html



#6 Spoonsize

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Posted 20 May 2019 - 06:40 AM

EQ5 = HEQ5, same belt drive kit for each. It worked in my EQ5 Sirius.
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#7 Spoonsize

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Posted 20 May 2019 - 06:42 AM

http://astro-baby.co...ild/heq5-m1.htm
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#8 mwr

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Posted 20 June 2019 - 05:36 AM

Thanks for the hints!

 

However, it seems that Rowan Astronomy does offer a belt kit only for the HEQ5. Could you share the links for the online instructions to take the EQ5 apart?

 

Additionally, I will test if imbalancing the mount in Dec-axis has an positive effect (as suggested by Michael Covington: http://www.covington...tes2/index.html

Indeed, imbalancing the mount in Dec-axis has a positive effect !! 

 

Although the sawtooth profile is still present, guiding performance has improved:

 

static friction



#9 Der_Pit

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Posted 20 June 2019 - 06:14 AM



EQ5 = HEQ5, same belt drive kit for each. It worked in my EQ5 Sirius.

The Sirius is a rebranded HEQ5, so of course that works.

EQ5 and HEQ5 have different gear teeth numbers (144 vs.135), see, e.g., on the page of the EQMOD Project


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