Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

HEQ5 - RA Axis Issue

  • Please log in to reply
8 replies to this topic

#1 rob77

rob77

    Vendor - FAST platesolver

  • -----
  • Vendors
  • topic starter
  • Posts: 1,000
  • Joined: 25 Feb 2012
  • Loc: Cuneo (Italy) / Belo Horizonte (Brazil)

Posted 28 July 2021 - 10:37 AM

Hi Mates!

 

I did my 12-years-old HEQ5 maintenance following Martin's Youtube videos (that are really excellent, actually) last Sunday and yesterday I tested it on the field.

DEC is backlash free and the guidance is excellent while I have some issues on the RA axis.

Once I finished the maintenance on Sunday, with the RA clutch closed, I was feeling a kind of backlash on the RA axis: when moving up and down the counterweight bar, actually the RA axis was doing small movements. Like swings.
So the first idea was to tighten and loosen respectively the top and bottom little screws as much as allowed.
I did it but this sort of backlash unluckily didn't go completely away. The RA axis is still able to swing if touching the counterweight bar, with the clutch closed.

Anyway, with this configuration I tried some guiding yesterday night and:

  •     DEC excellent (0 backlash)
  •     RA with big hops, even visible by simply looking at the PHD2 video streaming. The RA seemed to be pretty much swinging

At first glance I thought that this terrible RA behaviour root cause was its residual movements mentioned above but I am really not so sure about that anymore.

 

So I started convincing myself of the other way round: the small swinging I can feel on the RA axis (with the clutch tightened) is not a real issue while having closened too much the worm and the crown gear could be the cause of these jumps. I undid it this morning: loosened the upper little screw and tightened the lower one and I am planning to retest ASAP.

In the meanwhile, if anyone might have some tips for this situation, it would be great!

 

[EDIT]: Just a note: it's not just a matter of bad guidance along the RA axis. I could see yesterday night oscillations/swings in the RA direction simply looking at the PHD2 streaming. The frequency is pretty much high (seconds) but not regular.

 

Thanks so much in advance.

Bests.

 

Roberto


Edited by rob77, 28 July 2021 - 11:19 AM.


#2 Supernova74

Supernova74

    Mercury-Atlas

  • -----
  • Posts: 2,759
  • Joined: 25 May 2020
  • Loc: Epsom surrey near (London)

Posted 28 July 2021 - 11:26 AM

I’ve never attempted to dismantle a GEM before and give it a service.however from the sound of things sounds like the RA is possibly not meshing,or engaging properly to the clutch.ive always found a practical little tip if I’m uncertain or unaware how a item is supposed to be dismantled and then re-assembled  again is to take photos on my device it takes seconds to do and definitely got myself out of trouble before in the past.



#3 rob77

rob77

    Vendor - FAST platesolver

  • -----
  • Vendors
  • topic starter
  • Posts: 1,000
  • Joined: 25 Feb 2012
  • Loc: Cuneo (Italy) / Belo Horizonte (Brazil)

Posted 28 July 2021 - 11:49 AM

like the RA is possibly not meshing,or engaging properly to the clutch

 

Yes, it could be a starting point, thanks.

I thought about that earlier today but I decided to not unmount it again before some new tests (potentially tonight) once I've released the upper screw and tightened the lower one if compared to yesterday.

 

Anyway, the swing that I can feel while moving the CW bar with the clutch tightened is like a snap: I can't really move the axis; it just has a very tiny amplitude "dry" swing.

And this swing, as mentioned in my post, is not even eliminated by tightening and loosening the upper and lower screws, respectively, as much as allowed.

At the beginning I thought it was just the CW bar that was loose but then I realized that the HEQ5 head was moving too so it wasn't the case.

 

Bests


Edited by rob77, 28 July 2021 - 11:54 AM.


#4 terrypaula

terrypaula

    Viking 1

  • *****
  • Posts: 557
  • Joined: 20 Feb 2018

Posted 28 July 2021 - 11:56 AM

I agree with supernova.  It sounds as though the RA gears aren't meshing properly.  You may have to make some adjusts to the RA worm gears.  I'm sure there are some videos on the Inter-web.  Can you possibly show what PHD2 is saying?



#5 rob77

rob77

    Vendor - FAST platesolver

  • -----
  • Vendors
  • topic starter
  • Posts: 1,000
  • Joined: 25 Feb 2012
  • Loc: Cuneo (Italy) / Belo Horizonte (Brazil)

Posted 28 July 2021 - 12:03 PM

I agree with supernova.  It sounds as though the RA gears aren't meshing properly.  You may have to make some adjusts to the RA worm gears.  I'm sure there are some videos on the Inter-web.  Can you possibly show what PHD2 is saying?

If I understood Supernova correctly, he was suggesting to check the RA meshing with the clutch rather than with the gear.

As mentioned above I already played with the worm and crown gear distance, putting them as much close as allowed (before starting not rotating anymore using the pad).

Even in this condition the swing was still present.

 

Earlier today I reversed the adjustments I did yesterday: I set the worm and the gear a little bit further each other (swing, of course, still present).

 

 

Can you possibly show what PHD2 is saying?

 

Sure, I'll do it tonight if the weather persists good and post it here.

 

Thanks.

Bests.


Edited by rob77, 28 July 2021 - 12:06 PM.


#6 Kevin Ross

Kevin Ross

    Apollo

  • *****
  • Posts: 1,404
  • Joined: 28 Mar 2018
  • Loc: Traverse City, MI, USA

Posted 28 July 2021 - 12:34 PM

If you're sure the worm is meshed with the worm gear as much as possible (without binding), then the next thing that can cause backlash like that is a loose worm bearing. There's a nut on the end of the worm shaft, that holds the worm shaft and worm bearing into place. That might be loose. It might be the worm is moving when moving the RA axis by hand.

 

Towards the bottom of this page has a photo. She calls them float adjusters.

 

https://www.astro-ba...nt-motor-gears/


  • rob77 likes this

#7 rob77

rob77

    Vendor - FAST platesolver

  • -----
  • Vendors
  • topic starter
  • Posts: 1,000
  • Joined: 25 Feb 2012
  • Loc: Cuneo (Italy) / Belo Horizonte (Brazil)

Posted 28 July 2021 - 03:19 PM

Thanks a lot Kevin.

Nailed down. It was the worm bearing little ring not properly tightened (I haven't thought about this option since during the maintenance I didn't remove it).

 

I mean, I haven't tested yet but at least it stopped swinging.

 

Bests



#8 Kevin Ross

Kevin Ross

    Apollo

  • *****
  • Posts: 1,404
  • Joined: 28 Mar 2018
  • Loc: Traverse City, MI, USA

Posted 28 July 2021 - 03:44 PM

Excellent! Glad it was something easy like that!


  • rob77 likes this

#9 rob77

rob77

    Vendor - FAST platesolver

  • -----
  • Vendors
  • topic starter
  • Posts: 1,000
  • Joined: 25 Feb 2012
  • Loc: Cuneo (Italy) / Belo Horizonte (Brazil)

Posted 28 July 2021 - 04:16 PM

Need to test but, you know, yesterday no clouds in a 300km range. Today, nearly raining LoL.

 

Thanks again!

 

Bests




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics