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Classic Telescopes Looking for Odds and Ends-The Ask Away Thread

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#776 moladso

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Posted 11 February 2024 - 07:25 PM

 

Newly acquired original Polaris mount missing the declination fine adjustment screw. I also seem to be missing the declination setting gauge, which I believe was just a sticker? In any case, it's missing on this mount. Any advice on how to replace these two items would be appreciated.

 

 

 

 

 

I think you are referring to the latitude fine adjustment screw. It is a normal screw with some type of knob on the end. It's very important for precise handling to have the tip rounded.

Here is a picture of the original screw.

 

Latitude adjustment screw
 

You are missing also the declination axis indicator, which is a small yellow piece of plastic with a triangle etched inside. I think you can do it with a laser printer and some plastic sheet.

 

Declination mark

 

Declination mark

 

You can also try to make the indicator and scale of the latitude axis with a laser printer from metallized sheet, silver background is easier than original black.

 

Latitude scale

 

I have made several missing scales like this and the result is more than acceptable.


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#777 ericb760

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Posted 11 February 2024 - 09:20 PM

I think you are referring to the latitude fine adjustment screw. It is a normal screw with some type of knob on the end. It's very important for precise handling to have the tip rounded.

Here is a picture of the original screw.

 

 
 

You are missing also the declination axis indicator, which is a small yellow piece of plastic with a triangle etched inside. I think you can do it with a laser printer and some plastic sheet.

 

 

 

 

 

You can also try to make the indicator and scale of the latitude axis with a laser printer from metallized sheet, silver background is easier than original black.

 

 

 

I have made several missing scales like this and the result is more than acceptable.

Can you do me one favor and measure the length of the latitude fine adjustment screw? I took one off of a CG-1 I had. It fits, but it is too long and I need to have it cut down to the proper size. Thanks! - Eric



#778 65&Counting

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Posted 16 February 2024 - 08:59 PM

Speaking of the Polaris mount - anyone have a Polar Alignment Scope for one of these? I have a black one I've redone but its missing the scope and it'd be great to find.

 

They seem to have a bushing piece that fits into the polar housing and the scope fits inside that and would need both.

Anywho - I'd be grateful and would happily compensate for shipping/handling/anything.

Thanks!



#779 apfever

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Posted 16 February 2024 - 09:36 PM

Hi Rich,  

 

Need a picture of the end of your Polaris mount where the polar scope inserts. There are two different bushing types, threaded and unthreaded, and different polar scope collars to match. The best thing to do is get the exact info you need from this forum and then post a detailed WANT ad in the classifieds. These polar scopes are hard to come by and not likely to be coughed up here, but I hope you do score one!   I have two but I also have three worthy Polaris set up so I could use another myself. I'm not actively looking for one though. I would forward any finds to you. 

There is a string in this forum from within the last couple of years that goes into good detail on the Polaris polar scope versions. I have some entries in that string but I'm not good with searches. It is an excellent string on these.

 

Neil


Edited by apfever, 16 February 2024 - 09:36 PM.

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#780 deSitter

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Posted 16 February 2024 - 10:49 PM

Hi Rich,  

 

Need a picture of the end of your Polaris mount where the polar scope inserts. There are two different bushing types, threaded and unthreaded, and different polar scope collars to match. The best thing to do is get the exact info you need from this forum and then post a detailed WANT ad in the classifieds. These polar scopes are hard to come by and not likely to be coughed up here, but I hope you do score one!   I have two but I also have three worthy Polaris set up so I could use another myself. I'm not actively looking for one though. I would forward any finds to you. 

There is a string in this forum from within the last couple of years that goes into good detail on the Polaris polar scope versions. I have some entries in that string but I'm not good with searches. It is an excellent string on these.

 

Neil

It's almost certain you can modify say the polar scope from an LXD55/75 or even buy a new one for a current medium duty mount (e.g. EXOS2) and modify that to work. It may just go in without complaint.

 

-drl


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#781 65&Counting

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Posted 17 February 2024 - 12:08 AM

Hi Guys - many many thanks again. Mine has an outside ?plastic? bushing (in the housing entrance) where the scope would insert that's smooth and is maybe screwed into some threads - the further in you look you can see some threads. Really appreciate the help and I'll post in the want ads for one when I know what I'm looking for. I'll try theLXD55/75 if all else fails - thanks guys! Here's the pix.

 

Oh Neil - any chance you might have a nice secondary mirror/holder for a 6"f/8 Cave? I've got a nice scope from a member (rare one with rotating rings) and had the secondary re-aluminized and now it doesn't want to go back into the formed 'tube' for it and sit correctly - still puzzling over what's wrong but it's starting to scratch it some so I'm on pause. I'm told these were a weird size and not easy to replace - if you had one it's worth whatever you want to charge me should you have an extra and many thanks for all the help for the myriad other things you've helped me on.

 

So back to the Polaris - here's the pix!

Attached Thumbnails

  • Vixen Polar Scope Entrance.jpg

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#782 deSitter

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Posted 17 February 2024 - 07:11 AM

Hi Guys - many many thanks again. Mine has an outside ?plastic? bushing (in the housing entrance) where the scope would insert that's smooth and is maybe screwed into some threads - the further in you look you can see some threads. Really appreciate the help and I'll post in the want ads for one when I know what I'm looking for. I'll try theLXD55/75 if all else fails - thanks guys! Here's the pix.

 

Oh Neil - any chance you might have a nice secondary mirror/holder for a 6"f/8 Cave? I've got a nice scope from a member (rare one with rotating rings) and had the secondary re-aluminized and now it doesn't want to go back into the formed 'tube' for it and sit correctly - still puzzling over what's wrong but it's starting to scratch it some so I'm on pause. I'm told these were a weird size and not easy to replace - if you had one it's worth whatever you want to charge me should you have an extra and many thanks for all the help for the myriad other things you've helped me on.

 

So back to the Polaris - here's the pix!

 

"Graduation" :)

 

I have several graduation that are also no useful more any days now.

 

-drl
 


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#783 deSitter

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Posted 17 February 2024 - 07:18 AM

Hi Guys - many many thanks again. Mine has an outside ?plastic? bushing (in the housing entrance) where the scope would insert that's smooth and is maybe screwed into some threads - the further in you look you can see some threads. Really appreciate the help and I'll post in the want ads for one when I know what I'm looking for. I'll try theLXD55/75 if all else fails - thanks guys! Here's the pix.

 

Oh Neil - any chance you might have a nice secondary mirror/holder for a 6"f/8 Cave? I've got a nice scope from a member (rare one with rotating rings) and had the secondary re-aluminized and now it doesn't want to go back into the formed 'tube' for it and sit correctly - still puzzling over what's wrong but it's starting to scratch it some so I'm on pause. I'm told these were a weird size and not easy to replace - if you had one it's worth whatever you want to charge me should you have an extra and many thanks for all the help for the myriad other things you've helped me on.

 

So back to the Polaris - here's the pix!

The LXD55/75, Exos2-GT, etc. various EQ5s probably use the same polar scope setup as the Polaris, because they pretty much cloned the rest of the SP mount so why not that as well?

 

On my 75, the polar scope rides in a device that allows the scope to be collimated via three little pusher screws. There are also some grub screws that allow the reticle to be aligned to the declination shaft. While this is not strictly necessary, it is useful for getting the RA to match the offset of Polaris from the pole by comparing the shaft to something like Stellarium zoomed in on the pole with coordinates displayed. This would be much harder just going back and forth to the reticle and the computer screen.

 

A new polar scope that works with the above mounts costs about $80. It does NOT include the adjustment mechanism. Check your mount to see if that mechanism is already in place. Then you just wrap enough tape around the new polar scope that it fits snugly into the recess.

 

-drl


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#784 65&Counting

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Posted 17 February 2024 - 08:47 AM

This one is set up the same way - needs the three pusher screws and grub screws it doesn't have.

 

I'll look around for one of the $80 offerings available or post an ad - who sells these?

 

Rich



#785 65&Counting

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Posted 17 February 2024 - 09:00 AM

Found 'em - many thanks - I would have had no idea given how 'ubiquitous' these mounts are that this would be such a scarce part - you just never know.



#786 deSitter

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Posted 17 February 2024 - 09:15 AM

Found 'em - many thanks - I would have had no idea given how 'ubiquitous' these mounts are that this would be such a scarce part - you just never know.

Even without the fine adjustment, if done carefully with tape you can get any slim polar scope like the one for the Exos2 to fit in the aperture more or less accurately. You could even think about making your own.

 

-drl


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#787 apfever

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Posted 17 February 2024 - 09:35 AM

Here's the 4 page string specific to the Polaris finder scope. It includes various cross references to substitutes as well as the different versions and individual parts.

 

LINK here

 

 

I don't think a coating that creeps over the edge of a secondary would be thick enough to cause an issue with reinstalling. Maybe it is?  I suggest you clean, and inspect the holder for anything including deformations. Maybe the holder is a split cylinder that can be slightly expanded till the mirror is in place?  I'd need for you to measure yours with calipers, including thickness. I have a few loose secondaries but the trivial difference of a new coating makes me balk at going by size. Are you sure you got the same secondary back? Have discerning photos to compare with?


Edited by apfever, 17 February 2024 - 10:02 AM.

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#788 65&Counting

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Posted 17 February 2024 - 02:42 PM

Neil - many thanks for the Polaris info. Will PM you about the Cave diagonal issue with pix.



#789 tim53

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Posted 18 February 2024 - 04:59 PM

My apologies up front, as this is clearly not a classic telescope.  But my wife picked it up from the swap meet yesterday for $2, and I've put a cheap 17mm Kellner in it to sight on the trees across the valley, and it's not bad!

 

But it was incomplete.  The front dust cover is missing and the eyepiece for the finder is missing.  Worse, one of the feet on the base was broken off, apparently.  Their rubber feet that screwed into the base.  I suppose I could 3d print something, but wondered if someone has one of these scopes in worse condition than this one (optics are spotless!) who'd want to part with parts.

 

Here's the scope:

 

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#790 Terra Nova

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Posted 19 February 2024 - 08:06 AM

My apologies up front, as this is clearly not a classic telescope.  But my wife picked it up from the swap meet yesterday for $2, and I've put a cheap 17mm Kellner in it to sight on the trees across the valley, and it's not bad!

 

But it was incomplete.  The front dust cover is missing and the eyepiece for the finder is missing.  Worse, one of the feet on the base was broken off, apparently.  Their rubber feet that screwed into the base.  I suppose I could 3d print something, but wondered if someone has one of these scopes in worse condition than this one (optics are spotless!) who'd want to part with parts.

 

Here's the scope:

I always thought those Baby Newts were cute! Is that the 76mm?


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#791 tim53

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Posted 19 February 2024 - 10:13 AM

Yes it is. 


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#792 norvegicus

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Posted 19 February 2024 - 11:02 AM

I'd 3D print the dust cap and a set of feet.  It will cost you less than someone shipping you a free part and you could be done today.  I like Sainsmart TPU for this stuff, it's not too flexy and prints well, but really anything will do.

 

If it's an f/4 Newt and not a Bird-Jones you don't really need a finder scope.


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#793 PaulEK

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Posted 21 February 2024 - 10:54 AM

In the current Sky & Telescope (April, '24), the 'Astronomer's Workbench' column by Jerry Oltian describes the Eclipsinator. It's a simple solar projection setup that, in the article, uses an old pair of binoculars out at the end of a rod, with a large screen at the other end that allows large projected images of the sun. I'd like to make one, but I think using an old finder would be easier. I -- and my club -- do lots of outreach, and with the upcoming eclipse as well as coming to solar maximum, I think this would be a good addition to my outreach kit.

 

I'm wondering if anyone has an old, preferably very beat up, straight through finder they'd be willing to part with. I have several finders, but they are all right angle correct image. I could figure out a way to modify one, but thought I'd ask here first. A 50 mm objective would be especially nice since it would make for a brighter image, but a 30mm would work okay, I think. I'd probably just need to make the rod shorter and the image smaller to get a good,bright image.

 

I almost certainly won't finish this project before the eclipse, since I've got so many other irons in the fire to get ready before then, but the eclipse will bring lots of attention to the sun for quite a while, and having this will let me show people something on any clear day, without folks having to wait in line to look through a filtered scope.



#794 cavedweller

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Posted 21 February 2024 - 11:08 AM

I am surprised they would use binoculars in a full solar energy optical system. Seems like the heat bouncing around in the prisms would cause problems if done for an extended period, especially if the prisms are cemented. Maybe that's why you say an "old pair" of binoculars. The straight through finder seems like a better idea but watch out for the plastic parts melting.

 

Oh, and put a clear sign up warning folks not to try and look through the finder. Kids can sneak in pretty quick and disaster may strike.


Edited by cavedweller, 21 February 2024 - 11:10 AM.

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#795 deSitter

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Posted 21 February 2024 - 11:11 AM

I am surprised they would use binoculars in a full solar energy optical system. Seems like the heat bouncing around in the prisms would cause problems if done for an extended period, especially if the prisms are cemented. Maybe that's why you say an "old pair" of binoculars. The straight through finder seems like a better idea but watch out for the plastic parts melting.

Yes, terrible idea unless they are just sacrificial junk.The prisms are cemented together and they will not do well. Even worse, the eyepieces are probably Kellners or Erfles and will have cemented lenses.

 

-drl



#796 reverse_syzygy

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Posted 26 February 2024 - 04:53 PM

Can you do me one favor and measure the length of the latitude fine adjustment screw? I took one off of a CG-1 I had. It fits, but it is too long and I need to have it cut down to the proper size. Thanks! - Eric

I'm not who you were talking to / asking, but I didn't see a response.  (and my mount is taking up space, and calipers were handy, so...)

 

Polaris mount fine latitude bolt on mine is as I got it, sans the little torque pin.  

 

Looks to be ~ 1.89" / 48mm end to end.

 

img: https://i.imgur.com/kt6f5CH.jpeg


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#797 reverse_syzygy

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Posted 26 February 2024 - 05:00 PM

Their rubber feet that screwed into the base.

if you can't find direct replacement, maybe just replace all at once?  (ex. Amazon 16-pack for $9)
 


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#798 Kasmos

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Posted 26 February 2024 - 07:01 PM

or if you don't want 16 of them

 

https://www.acehardw...re-pads/5425277


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#799 norvegicus

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Posted 26 February 2024 - 07:09 PM

Or 3D print them at home in about 15 minutes for about 30 cents.  It might take another ten minutes to draw the model.


Edited by norvegicus, 26 February 2024 - 07:09 PM.


#800 ericb760

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Posted 26 February 2024 - 09:37 PM

I'm not who you were talking to / asking, but I didn't see a response.  (and my mount is taking up space, and calipers were handy, so...)

 

Polaris mount fine latitude bolt on mine is as I got it, sans the little torque pin.  

 

Looks to be ~ 1.89" / 48mm end to end.

 

img: https://i.imgur.com/kt6f5CH.jpeg

Thanks. I have a bolt from a CG-1 that even has the torque pin. Now I just have to cut it down to the dimensions you provided.




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