|
Hi Everybody,?
Ive been a long time lurker of this forum, but I come to you today with a question.?
My Celestron branded G-11 rocks back and forth in altitude by 1 notch on the altitude markers. I cant seem to make it stop no matter what I try. I was briefly successful earlier today in making it stop, only for it to break loose again about 20 minutes ago while I was setting up to test it out.?
Im going to be trying a few things out and will let you all know if I find a solution. I was hoping that maybe someone among you all has experienced this issue before and knows a fix??
Thanks,? - Norm?
|
Norm,
Here's an webpage in Italian that shows complete disassembly of G11 mount. You my need to translate. This link is a Chrome translated page.
Don
toggle quoted message
Show quoted text
----- Original Message ----- From: "normanrevere@... [Losmandy_users]" <Losmandy_users@...> To: <Losmandy_users@...> Sent: Friday, December 29, 2017 5:10 PM Subject: [Losmandy_users] Issues with Altitude assembly in older G11 Hi Everybody,
Ive been a long time lurker of this forum, but I come to you today with a question.
My Celestron branded G-11 rocks back and forth in altitude by 1 notch on the altitude markers. I cant seem to make it stop no matter what I try. I was briefly successful earlier today in making it stop, only for it to break loose again about 20 minutes ago while I was setting up to test it out.
Im going to be trying a few things out and will let you all know if I find a solution. I was hoping that maybe someone among you all has experienced this issue before and knows a fix?
Thanks,
- Norm
|
Hi Norm,
This problem is probably caused by there being too much movement in the screw shaft due to a grub screw coming loose. I don't have a CG11 mount but I think the G11 is identical mechanically inside the base. There should be a collar that has a grub screw that locks the collar and thrust bearing retainer, this is what limits the in and out movement of the threaded rod. If the grub screw comes loose the collar may move on the threaded rod allowing too much movement of the threaded rod allowing the brass plug to move which lets the head move fore and aft as you describe. To fix this you need to disassemble the base and get the spacing right and then tighten up the grub screws to hold it in place as it should be. This issue is easily corrected if you have a few hand tools and some patience. Just take it apart and have a look, start at the bottom by removing the big button headed hex bolt and the two locking bolts on the top side of the base. The rest will be obvious once you can see the internal base parts. Keep us posted.
Chip? ?
|
Hi Don,?
That looks like what I did earlier today. I ended up getting some pretty good results tonight, so I'm a little less concerned about my previous issue. Thanks for the link!?
- Norm?
?
Norm,
Here's an webpage in Italian that shows complete disassembly of G11 mount. You my need to translate.
This link is a Chrome translated page.
Don
----- Original Message -----
From: "normanrevere@... [Losmandy_users]" <Losmandy_users@...>
To: <Losmandy_users@...>
Sent: Friday, December 29, 2017 5:10 PM
Subject: [Losmandy_users] Issues with Altitude assembly in older G11
> Hi Everybody,
>
>
> Ive been a long time lurker of this forum, but I come to you today with a question.
>
>
> My Celestron branded G-11 rocks back and forth in altitude by 1 notch on the altitude markers. I
> cant seem to make it stop no matter what I try. I was briefly successful earlier today in making
> it stop, only for it to break loose again about 20 minutes ago while I was setting up to test it
> out.
>
>
> Im going to be trying a few things out and will let you all know if I find a solution. I was
> hoping that maybe someone among you all has experienced this issue before and knows a fix?
>
>
> Thanks,
> - Norm
>
--
(732)-618-1149
President of the Colorado State University Astronomy Club Ecosystem Science ?? & Sustainability? ?
|
I noticed that earlier but let it go thinking my issue was somewhere else. I'm going to tear apart the mount tomorrow morning when I get the chance. Thanks for the tip, and I'll keep you all posted!?
- Norm?
?
Hi Norm,
This problem is probably caused by there being too much movement in the screw shaft due to a grub screw coming loose. I don't have a CG11 mount but I think the G11 is identical mechanically inside the base. There should be a collar that has a grub screw that locks the collar and thrust bearing retainer, this is what limits the in and out movement of the threaded rod. If the grub screw comes loose the collar may move on the threaded rod allowing too much movement of the threaded rod allowing the brass plug to move which lets the head move fore and aft as you describe. To fix this you need to disassemble the base and get the spacing right and then tighten up the grub screws to hold it in place as it should be. This issue is easily corrected if you have a few hand tools and some patience. Just take it apart and have a look, start at the bottom by removing the big button headed hex bolt and the two locking bolts on the top side of the base. The rest will be obvious once you can see the internal base parts. Keep us posted.
Chip? ?
--
(732)-618-1149
President of the Colorado State University Astronomy Club Ecosystem Science ?? & Sustainability? ?
|
I have a G8 from about the same vintage, so there are similarities. If I understand from your post, you are seeing the fact that the mount doesn't lock in altitude. This is the same behaviour as line and to my understanding is why Scott introduced the second bolt on the Altitude block after people started adding it DYI. I have never found this behaviour to be an issue as I make the altitude adjustment with the mount weighted.?
Bill Gardner? --
_____________ Pictor Observatory
Twitter: @pictorobs
Minor Planet 21350 - billgardner
|
Hi Norm
Bill Gardner is correct.?? On later mounts a altitude lock bolt was added.? Does you mount have this?
Here's a pic with the .??
Here's a pic of the .
Looks
I have heard of Scot Losmandy modifying the older mounts to bring them to newer spec.? He's very good like this, has great pride the older workhorses are still getting use.?? Of course the best thing is that most mounts can be brought up to modern spec which make them an excellent long term buy..IMHO!
Brendan
.
|
Brendan, those links only take you to a Google search page. On my computer anyways. Just in cast somebody else wants to see what they look like. Like me.
Greg S.
|
toggle quoted message
Show quoted text
Brendan, those links only take you to a Google search page. On my computer anyways. Just in cast somebody else wants to see what they look like. Like me.
Greg S.
|
I too have an older G-11 mount that lacked the locking bolt that was added on to later models.
Having a low-cost lathe/mill machine - I decided to take the mount apart, and I modified the base to permit the addition of a locking bolt.? ALSO - I changed the adjustment bolt - converting it from (this is from memory...so it is definitely a IIRC) - a 3/8" National Coarse (16 t.p.t.) thread to a 3/8" National Fine (24 t.p.i.)? thread.? I made replacement parts so that now - a turn of the altitude adjustment knob results in a smaller adjustment, making it easier to 'home in' on the desired value.? I loosen the bolts and make the adjustments by RAISING (never lowering) if possible, so that any backlash effects are minimized.
Even the old mounts can be modified to incorporate newer mount improvements - and these things will keep going strong for decades!
Mike
|
|
|
Yeah those are the links...thanks Bryan...no idea why they disappeared on my post.? Many thanks for fixing.
Brendan
|
|
|
Paul,
What are your saying? What's dangerous about the images??
Chip
|
I think Paul has noticed this:? ... the astromart ad picture of the CG11 shows the Elevation axis bolt with no flat washer under its bolt head.? It would be important to have that in place, to keep the brass center rod from slipping out the black side plate.?
The more modern system shows the center axis bolt, and the bolt through the slot, both bolts have flat washers under their caps.
I think the bolt through the slot not only locks thevelevation, but also acts to prevent side to side movement of the upper portion of the mount, though I've not experienced any trouble. ..front to back, or side to side...with my own CG11.??
Best, Michael?
|
Chip,
Anyone doing what is shown in the image is taking a risk.
The washer at the end of the R.A. shaft prevents the counterweight accidentally sliding off the shaft.
In the event it did, it could seriously injure someone.
Regards
toggle quoted message
Show quoted text
Paul,
What are your saying? What's dangerous about the images??
Chip
|
I think you mean the dec shaft.? But yes, the counterweight slipping off while it’s being adjusted could hurt someone, and/or damage the ‘scope when it slams against the mount about 1/2 second after the counterweight departs.?
toggle quoted message
Show quoted text
On Dec 30, 2017, at 8:58 PM, Paul Homer phomer60@... [Losmandy_users] < Losmandy_users@...> wrote:
Chip,
Anyone doing what is shown in the image is taking a risk.
The washer at the end of the R.A. shaft prevents the counterweight accidentally sliding off the shaft.
In the event it did, it could seriously injure someone.
Regards
Paul
Paul,
What are your saying? What's dangerous about the images??
Chip
|
At 21:00 30-12-17, brenatlilydale@... [Losmandy_users] wrote: On later mounts a altitude lock bolt was added. Does you mount have this? My G-11 has two bolts on each side. Do I need to loosen all four before adjusting the altitude, or just the two that run in slots? David
|
Hi David....if you have the 2 bolts each side.? Usually you can leave the pivot bolt a little loose...not much just a little and undo the upper tangent bolt a little to make altitude adjustments, nip it back up when done.
From experience, leaving the lower bolt a little loose is ok but nipping the upper bolt when altitude adjustments are done always throws out the mount out a little in "Alt".? You get a feel for how much it moves when tightening and allow for it.? Also no need to over tighten.
It ius also thrown out in "Alt" depending on which side bolt you tighten first.?? One side thrusts it one way the other the opposite.? Its just adding a little twist to the mount to throw out all your precise adjustments!
Grrrr
Brendan
|
Hi Paul,
I thought the OP was asking about his altitude adjustment moving around. What's the toe saver have to do with anything??
Chip
|
Michael Herman