22 replies to this topic

[Rigel_10]

Hello..I have a Twilight 1 mount about a year old, I did use it for a C8 but now I use it for a lighter 90mm refractor. But the mount has play in it now, because of the less weight the head wobbles. If it was heavier like before it stops the wobble effect.

Is there anyway to tighten up the moving head to the tripod?
I've removed the top piece but there's nothing there to tighten up? I hope this makes sense?

Thanks

[cookjaiii]

The wobble is probably a consequence of the long moment arm of your refractor.  

 

There are some general remedies for taming the wobble.  Make sure your refractor is balanced front and back on the mount.  Keep the telescoping legs or the tripod as short as practicable. Look up the modifications other CNers have posted here about stiffening that mount by adding bracing. Here are a couple examples.

 

https://www.cloudyni...t#entry13257022

 

https://www.cloudyni...t#entry13344527

 

A little bit of wobble may be unavoidable with your refractor on the Twilight I.

 

Good luck!

[Rigel_10]

Thanks...the mount problem is between the two parts where it moves, there's a loosening of the two parts...a gap that needs tightened but I see no way to do that?
The weight of a C8 keeps it tightened but with no weight or lighter weight it has a little movement now.
I think it's just the design and there's no adjustment for the mount loosening up.. I'll probably just live with it for now.
Greetings

Edited by Rigel_10, 28 September 2024 - 07:07 AM.

[Skywatchr]

Thanks...the mount problem is between the two parts where it moves, there's a loosening of the two parts...a gap that needs tightened but I see no way to do that?
The weight of a C8 keeps it tightened but with no weight or lighter weight it has a little movement now.
I think it's just the design and there's no adjustment for the mount loosening up.. I'll probably just live with it for now.
Greetings

Which "the two parts"?  The mount is made up of several parts.

[Rigel_10]

Which "the two parts"? The mount is made up of several parts.

Sorry...It's the Azimuth motion (right to left), It's a little loose, and as I aim the scope and let go it moves. If I hold down pressure in the middle to simulate weight it's okay but with the lighter scope there's play in the Azimuth where it connects to the tripod.
I would show a pic but it's difficult on my phone with the size limitations on here.
Anyway... there's enough play to effect the viewing experience.

[Skywatchr]

Sorry...It's the Azimuth motion (right to left), It's a little loose, and as I aim the scope and let go it moves. If I hold down pressure in the middle to simulate weight it's okay but with the lighter scope there's play in the Azimuth where it connects to the tripod.
I would show a pic but it's difficult on my phone with the size limitations on here.
Anyway... there's enough play to effect the viewing experience.

Take the 4 bolts out and remove the cover.  There will be an axle nut to snug up, then put the cover back on.

[Rigel_10]

Here's a pic... there's a center Axis screw but no adjustment. 

And there's nothing underneath to tighten. It looks like there's a round pin on the Axis screw that may be like a cotter pin but not sure if you can really see it in this pic, ever photo I try to upload is of course too big! ...so this is all I came up with. Maybe someone that had one of these mounts knows?

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[Skywatchr]

Here's a pic... there's a center Axis screw but no adjustment. 

And there's nothing underneath to tighten. It looks like there's a round pin on the Axis screw that may be like a cotter pin but not sure if you can really see it in this pic, ever photo I try to upload is of course too big! ...so this is all I came up with. Maybe someone that had one of these mounts knows?

Too bad you just can't resize it to the required size, then upload.  It's too small as it is. Almost any editing software can resize.

They put it together somehow, so there is a way to get it apart to take up the slack.  Too bad it isn't in my hands.

[Rigel_10]

I'm still looking for the axial nut you said would be there?...‍♂...would have been super easy to snug up! But obviously our friends in China built it a little different then shade tree mechanics here in the states.

But yeah, was hoping someone actually knew?‍♂

[rgk901]

I have the svbony version but think they are similar designs...the nut is underneath not under the arm pull it off the tripod and check

[rgk901]

here's a quick google

https://theamateuren...drive-assembly/

[Rigel_10]

Thanks RGK901...I see where it is now, I'll have to dig deeper into the mechanism than I wanted but it will be nice to tighten it up more, not sure but it may have come from the factory a tad loose?
Thanks again!

[rgk901]

if you're already in there, put some loctite on a clean thread to keep it from spinning loose again.

Edited by rgk901, 28 September 2024 - 07:36 PM.

[Rigel_10]

Will do! 👍

[Skywatchr]

here's a quick google

https://theamateuren...drive-assembly/

I knew it was in there somewhere.  If it wasn't on the top, it had to be in the bottom.

[Skywatchr]

Thanks RGK901...I see where it is now, I'll have to dig deeper into the mechanism than I wanted but it will be nice to tighten it up more, not sure but it may have come from the factory a tad loose?
Thanks again!

It didn't.  The nut probably worked loose over time from the loads being off balance putting pressure (friction) on the nyloc nut.  It's probably best to put a new nyloc nut on in addition to a dab of blue locktite on clean threads.

[Rigel_10]

What I learned was the all thread bolt they use is not really up to the task, it's only about a quarter inch thick and it needs to be 3/8 or even a half inch would be better. Would be a lot beefier and could handle the load for the lifetime of the mount. But the undersized (imo) bolt they use is going to be trouble later on.

But for now it's good,
Thanks everyone.

[Skywatchr]

What I learned was the all thread bolt they use is not really up to the task, it's only about a quarter inch thick and it needs to be 3/8 or even a half inch would be better. Would be a lot beefier and could handle the load for the lifetime of the mount. But the undersized (imo) bolt they use is going to be trouble later on.

But for now it's good,
Thanks everyone.

Is it possible to change it out?  You would have to remove the original, obtain or cut a new one to length (I would use stainless), drill the hole the appropriate size and tap the threads, and use Loctite to secure it instead of the pin they used.

[rgk901]

I agree, for just pennies they could have used a larger diameter bolt with a larger diameter washer/bearing surface to increasing these cheap units load/stiffness capacity substantially.... although a stiffer/thicker arm would be needed too ..like they did for the svbony version... although the svbony kept the smaller diameter bolts

Edited by rgk901, 01 October 2024 - 09:04 AM.

[Skywatchr]

I agree, for just pennies they could have used a larger diameter bolt with a larger diameter washer/bearing surface to increasing these cheap units load/stiffness capacity substantially.... although a stiffer/thicker arm would be needed too ..like they did for the svbony version... although the svbony kept the smaller diameter bolts

You have to remember Vixen offered it for use with their own smaller, lighter refractors at the time. It wasn't meant for larger scopes, hence the name "Twilight 1".  The Twilight II is a bit more heavy duty, uses larger hardware, along with other improvements.

A 3/8-16 bolt made of hardened steel, or stainless steel is plenty heavy enough to secure these mounts to a good tripod which is what the SVBONY uses.  Less expensive soft steel bolts will more easily bend and/or flex under load, with the threads also stripping more easily.  I have yet to break or strip any stainless steel hardware.  Stainless steel hardware has become very inexpensive these days, especially on Amazon.

[rgk901]

You have to remember Vixen offered it for use with their own smaller, lighter refractors at the time. It wasn't meant for larger scopes, hence the name "Twilight 1". The Twilight II is a bit more heavy duty, uses larger hardware, along with other improvements.
A 3/8-16 bolt made of hardened steel, or stainless steel is plenty heavy enough to secure these mounts to a good tripod which is what the SVBONY uses. Less expensive soft steel bolts will more easily bend and/or flex under load, with the threads also stripping more easily. I have yet to break or strip any stainless steel hardware. Stainless steel hardware has become very inexpensive these days, especially on Amazon.

I was speaking to the bolts inside the alt/az housings not the tripod female thread bolt size... if the bolts ( and larger bearing seurface) were 3/8 inside them these mounts would be beastly good!

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Edited by rgk901, 02 October 2024 - 10:48 AM.

[Oldfracguy]

I had a Twilight !, and then another one.  I remember not so fondly having to periodically tighten up that internal 10 mm nut to get rid of the wobble.  I also remember having to take the entire mount head off just to fold up the tripod legs, so I replaced that lomg T-handle rod with a length of M10x1.5 threaded rod.  Here is a CN thread I posted about three years ago on how to do it:

 

https://www.cloudyni...s +to +twilight

 

Something else you will have to do every so often is to tighten the cams on the ends of the position control shafts using snap ring pliers like these:

 

 

 

You can use either the 90° angled tips (shown below), or the straight ones with the smaller tips at the end:

 

 

 

At each end of the Twilight I (and some other mounts as well) position control shafts are two shiny silver caps with a pair of dimples on opposite sides (green arrows):

 

 

 

Remove the position control handles using a Philllips screwdriver, and then back off on the small recessed Allen grub screws on each end of the gear shafts (orange arrow).  Now, using the snap ring pliers with the tips inserted into each dimple on the silver end cap, tighten that end cap until you feel it become snug.  Do the same at the other end of the gear shaft.  After that, retighten those two Allen grub screws at each end.

 

Now the slop, or hysteresis, in your Altitude and Azimuth position controls should be eliminated.  If you discover that the position controls are now way too tight, then use the snap ring pliers to loosen slightly each silver end cap just a bit.

Edited by Oldfracguy, 03 October 2024 - 11:36 PM.

[Oldfracguy]

I found that the solution to the Twilight I was a Celestron CG-4 converted to Alt-Az mode.  Here is mine with a C8 aboard:

 

 

 

and here is it with a "larger-than-90mm" refractor, an AT115EDT, that it managed with no trouble: