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Zeiss Coudé telescope rebfurbish

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#26 Peter Ceravolo

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Posted 16 January 2019 - 11:40 AM

Peter, glad to see this historic instrument that I remember from the planetarium years ago has and it up someplace where it's going to undergo a major refit and end up back in service. Being a child who grew up in the bank near Vancouver in the seventies, I recall this telescope vaguely. Later, as a member of our RASC Vancouver I got a history lesson from Dan, the resident operator of the observatory there and its equipment, and often wondered what happened to this scope after they replaced it with the 6 inch regular refractor. One question I do have, is about the light path of the scope. There are a couple of folded refractors floating around Vancouver, a pair of them built by some friends using the same Optics from some European company, and both ending up being 6 in ff15 versions.

Hi John,

Glad to hear from you!

I'm old enough now to appreciate history... :) So I'm trying to gather as much historical info and images of the instrument as possible.

Sky News editor Gary Seronik remembers the telescope well from his days in Vancouver. As does Jim Fails here in the Okanagan, but the only pics I have of the early era I posted early on in this thread.

Spread the word around the astro community and see if you can gather more info/pics.

Thx

Peter


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#27 Peter Ceravolo

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Posted 16 January 2019 - 11:48 AM

Perhaps, you can fix the wire dent in place by polishing a welded over blob?

That would be really, really hard to do. I think you'd have to spin the monster shaft in a lathe. A big lathe....

I came really close to having to scrap the scope for parts since it might have cost tens of $K to fix the problem.



#28 Astrojensen

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Posted 16 January 2019 - 02:58 PM

I had never heard of wire race bearings, but apparently it's the way to go when you need large diameters at a low price that fit in a tight space.

It's no surprise that the craftsmen that built these telescopes have either long retired or passed on, so it would seem that Zeiss is not able to support their classic instruments. I researched and called many companies that work with wire bearings to see if the mount was salvageable. A big problem was that the wire was pressed into the metal, it could not be easily replaced. This is curious because that is supposed to be be one of the advantages of a wire race bearing. Companies that have experience with wire bearings, from North America to the UK and EU could not help with this odd ball classic telescope's bearing problem.

Zeiss can still renovate old telescopes and equipment. They have a 4H club in Jena that specializes in it. 

 

It is highly likely that Zeiss made the wire bearing from scratch themselves, IE only the balls are bought and the wire is just normal hardened steel wire for making springs, perhaps roughly bent into the right shape with a lathe. Zeiss Jena used a lot of solutions like that, because of the bad communist economy, which meant that off the shelf components were simply not available. It was easier for them to design and build ridiculously complex telescopes from scratch than to rely on buying components from elsewhere, even if it was something as simple as a ball bearing. Replacing the wire probably looks daunting, but I'm willing to bet that it's actually fairly straightforward (if somewhat involved and time-consuming), if you know how to do it. It's probably just cut to length and then either pressed into place or pounded into place with a mallet and copper or bronze tools specially made for the job on a lathe, to get the right curve. It's a bit hard for me to properly explain in english, because I don't always know the correct terms. 

 

It's mostly guesswork, so I could be wrong, but I know from experience, that a lot of things we now think of as highly complex was actually once considered low tech and easy to do. I suspect this is one of them. 

 

 

Clear skies!
Thomas, Denmark


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#29 halx

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Posted 16 January 2019 - 04:17 PM

It's mostly guesswork, so I could be wrong, but I know from experience, that a lot of things we now think of as highly complex was actually once considered low tech and easy to do. I suspect this is one of them. 

Sure they were. My idea about the welded blob is viable, but definitely not just one turn on a lathe, it could be weeks of buffing and hundreds of measuring the fit in place (if you strive for perfection, while it could be just an hour (per dent) of tooled work to convert the abrupt jump to a smooth wave).

 

By the way, you have that lathe on hands already. After grinding the bump to a rough fit, add a grinding object instead of one ball and finish the restored surface to perfection moving the axis in place over it.

 

"For parts" sounds like "vandalism" for this wonder. grin.gif


Edited by halx, 16 January 2019 - 04:23 PM.

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#30 Peter Ceravolo

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Posted 16 January 2019 - 05:21 PM

I really liked this counterweight. So simple, so elegant. And no, you do not need to rebalance this scope once it is balanced. The telescope mass is so high, no imagetrain or eyepiece will make any noticeable difference to the balance of the total telescope.

 

BTW Peter, do you have pictures of the declination axis assembly by any coincidence? Especially the region where the pinion from the polar axis goes into the "dogbone" part of the declination axis.

 

All the other images were highly appreciated yesterday by our project team. We were also impressed by the painting that was done. Probably we are going to paint our scope either the original colors or (off-)white. Rest via the e-mail.

Is this what you're referring to? It was in the batch of images I sent.

 

IMG_2440.JPG



#31 JohnH

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Posted 16 January 2019 - 05:44 PM

Hi John,

Glad to hear from you!

I'm old enough now to appreciate history... smile.gif So I'm trying to gather as much historical info and images of the instrument as possible.

Sky News editor Gary Seronik remembers the telescope well from his days in Vancouver. As does Jim Fails here in the Okanagan, but the only pics I have of the early era I posted early on in this thread.

Spread the word around the astro community and see if you can gather more info/pics.

Thx

Peter

I also have some vintage optics, from the Innisfil Observatory. http://urbexbarrie.b...bservatory.html

 

I possess the 24" f/5.6 primary and the secondary holder/focus mechanism. With its original optical formula, focus happens 12 inches behind the back face of the primary. With a tertiary mirror, this could also be made into a Coude focus telescope


Edited by JohnH, 16 January 2019 - 05:47 PM.


#32 Benach

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Posted 16 January 2019 - 06:48 PM

Peter: I meant what is in the "dogbone" between your left hand on that photo and the pinion? Could not find that in your photos. What is the counterpart of the pinion? etc. etc.



#33 Peter Ceravolo

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Posted 16 January 2019 - 08:00 PM

Peter: I meant what is in the "dogbone" between your left hand on that photo and the pinion? Could not find that in your photos. What is the counterpart of the pinion? etc. etc.

If "dogbone" refers to the small 45 degree spur gear, it is connected to the pinion I think you're referring to. The small 45 degree spur gear drives the larger 45 degree spur gear in the dec housing for motion in declination. A shaft connected to the gear in the big hollow RA shaft extends down to the observing position slow motion control.

 

IMG_2453.JPG



#34 Peter Ceravolo

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Posted 17 January 2019 - 03:54 PM

I really liked this counterweight. So simple, so elegant. And no, you do not need to rebalance this scope once it is balanced. The telescope mass is so high, no imagetrain or eyepiece will make any noticeable difference to the balance of the total telescope.

 

BTW Peter, do you have pictures of the declination axis assembly by any coincidence? Especially the region where the pinion from the polar axis goes into the "dogbone" part of the declination axis.

 

All the other images were highly appreciated yesterday by our project team. We were also impressed by the painting that was done. Probably we are going to paint our scope either the original colors or (off-)white. Rest via the e-mail.

 

Here are more pictures, post paint, of the declination housing. The actual declination axis stops short of the fold mirror, of course, but it is huge! The dec shaft ID is about 4.5" (to allow the objective's light to pass through) and about 10" long.

 

IMG_9205.JPG

 

The small hole below the large mounting flange reveals the declination gear (smeared in grease with teeth barely visible). The angled spur gear in the previous post engages this gear to provide dec motion.

 

IMG_9204.JPG

 

We had considered disassembling the dec axis to re grease, but the motion was smooth, we didn't have the proper tools, so we decided to leave well enough alone.

 

IMG_9206.JPG



#35 Peter Ceravolo

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Posted 17 January 2019 - 04:06 PM

Zeiss can still renovate old telescopes and equipment. They have a 4H club in Jena that specializes in it. 

 

It is highly likely that Zeiss made the wire bearing from scratch themselves, IE only the balls are bought and the wire is just normal hardened steel wire for making springs, perhaps roughly bent into the right shape with a lathe. Zeiss Jena used a lot of solutions like that, because of the bad communist economy, which meant that off the shelf components were simply not available. It was easier for them to design and build ridiculously complex telescopes from scratch than to rely on buying components from elsewhere, even if it was something as simple as a ball bearing. Replacing the wire probably looks daunting, but I'm willing to bet that it's actually fairly straightforward (if somewhat involved and time-consuming), if you know how to do it. It's probably just cut to length and then either pressed into place or pounded into place with a mallet and copper or bronze tools specially made for the job on a lathe, to get the right curve. It's a bit hard for me to properly explain in english, because I don't always know the correct terms. 

 

It's mostly guesswork, so I could be wrong, but I know from experience, that a lot of things we now think of as highly complex was actually once considered low tech and easy to do. I suspect this is one of them. 

 

 

Clear skies!
Thomas, Denmark

 

Thomas that is good to hear, but what I heard from some individuals in Germany is that there is no support, no parts, so please send details.

 

We actually did try to remove a wire from the bearing, no go. It would have been very destructive, at least given the tools and knowledge we have about such things.

 

I am not knowledgeable about Zeiss history, but I thought this instrument was fabricated in the west based on the marketing materials I have seen.... ?



#36 Astrojensen

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Posted 17 January 2019 - 04:34 PM

Thomas that is good to hear, but what I heard from some individuals in Germany is that there is no support, no parts, so please send details.

 

We actually did try to remove a wire from the bearing, no go. It would have been very destructive, at least given the tools and knowledge we have about such things.

 

I am not knowledgeable about Zeiss history, but I thought this instrument was fabricated in the west based on the marketing materials I have seen.... ?

I'll see if I can find some details about the Zeiss Jena 4H.

 

There was a 15cm coude manufactured in both the Zeiss West and Zeiss Jena, but they're very different scopes. The one you have is the Jena model. Believe it or not, but it was actually the cheaper of the two... 

 

Here's a picture of one: http://rasathane.en....tr/?page_id=106

 

 

Clear skies!
Thomas, Denmark


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#37 Astrojensen

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Posted 17 January 2019 - 04:38 PM

Link to Zeiss Jena 4H: http://www.4h-jena.de/en/start/

 

And a direct link to the group that restores astronomical equipment: https://www.4h-jena....geraetetechnik/

 

Given the list of scopes they've restored, I really don't think they should have much trouble with a 15cm coude...

 

 

Clear skies!

Thomas, Denmark


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#38 Astrojensen

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Posted 17 January 2019 - 05:02 PM

I seriously don't think there's anything these guys can't restore, maybe save for the Hubble Space Telescope... Everything else seems to be fair game. 

 

https://www.4h-jena....ro-Projekte.pdf

 

And they've already restored a Zeiss Jena 15cm coude, I see.

 

 

Clear skies!
Thomas, Denmark


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#39 Peter Ceravolo

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Posted 17 January 2019 - 05:14 PM

Link to Zeiss Jena 4H: http://www.4h-jena.de/en/start/

 

And a direct link to the group that restores astronomical equipment: https://www.4h-jena....geraetetechnik/

 

Given the list of scopes they've restored, I really don't think they should have much trouble with a 15cm coude...

 

 

Clear skies!

Thomas, Denmark

 

Yes I did contact the 4H company with the help of Markus Ludes. And I did see all the material you linked. Unfortunately for me, but fortunately for them, they never had to deal with the wire bearing damage so they could not help. But even if they could, it was obvious it would not be in my budget!

 

The Coude that you lined, I believe was a more modern unit, looks more sophisticated and I read that it is superior.

Here are a few images of the very western style brochure for the older telescope:

 

IMG_9208.JPG

 

IMG_9207.JPG


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#40 Peter Ceravolo

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Posted 17 January 2019 - 05:27 PM

We'll see on that in a few months. But Peter, I wonder: those two short movies of the RA-axis you have send me, are they a "before" and "after" your tweaking of the wire race bearings? if so, the difference is indeed huge!

Yes the movies were before and after. What I didn't mention before is the celebration that evening featuring a 3 olive martini... :-)


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#41 Benach

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Posted 17 January 2019 - 06:32 PM

Okay Peter, You seem to have just as much information on the internal parts of the declination axis as we do. No problemo. We are going to insert a small camera and illumination in the small hole next to the mounting flange. Pictures will be made a few weeks from now. Pictures will be shared of course but we need them to get an idea if it is possible to put a motor with clutch, second gear set and an encoder within that cavity. If that is possible, we can create a GoTo which is nearly invisible.

 

We also have to figure out a way to disassemble the declination axis. But we have a small machine shop that we can use to develop our own tools for this, if needed.

 

Indeed, I know that 4H club. I have had contact with them and the prices were, pun intended, astronomical.



#42 Peter Ceravolo

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Posted 17 January 2019 - 06:53 PM

Okay Peter, You seem to have just as much information on the internal parts of the declination axis as we do. No problemo. We are going to insert a small camera and illumination in the small hole next to the mounting flange. Pictures will be made a few weeks from now. Pictures will be shared of course but we need them to get an idea if it is possible to put a motor with clutch, second gear set and an encoder within that cavity. If that is possible, we can create a GoTo which is nearly invisible.

 

We also have to figure out a way to disassemble the declination axis. But we have a small machine shop that we can use to develop our own tools for this, if needed.

 

Indeed, I know that 4H club. I have had contact with them and the prices were, pun intended, astronomical.

 

That sounds difficult given the impossibly tight space.

 

Why not install a motor with pinion gear that engages the larger gear visible to the left in the picture? It would be encased in the RA housing which would be convenient.

 

IMG_2440.JPG

 

Or, one could install it in the huge RA shaft, engaging the existing gear via a clutch to allow the use of the manual motion control?

 

IMG_2453.JPG



#43 Benach

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Posted 18 January 2019 - 10:59 AM

I do not know how tight it is there. But this also sounds like an option. Nothing is certain yet. But indeed, I see some advantages in that position as well. But we also need to install an encoder there. If just the encoder fits there, then we will probably put the motor on that RA housing with probably an differential somehow.



#44 Peter Ceravolo

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Posted 20 January 2019 - 05:16 PM

The observer end of the Zeiss was in pretty rough shape. The handle bars, which when grasped and swung around rotated the polar shaft moved the instrument in RA. When the handle bars are rotated (twisted) the telescope moves in declination via a large number of gear couplings. The small, partially enclosed black knob is for fine motion in Dec.

 

The Dec setting circles as well as other components had been touched up with paint that had degraded over the years.

 

IMG_2339.JPG

 

The unit was completely disassembled, and stripped of paint and grease. Including the small Dec setting circles.

 

IMG_1661.JPG

 

IMG_0986.JPG

 

Masking the parts was important to ensure the mating parts surfaces were free of paint. We couldn't easily dissemble the setting circle hardware so it was carefully masked to be able to paint the housing. Having one person focused on the job makes fiddly work like this less frustrating and minimizes the risk of loosing parts.

 

IMG_1669.JPG

 

The re-finished component is as good as new, only the lettering in the Dec circles was left as is after a careful clean up.

 

IMG_9215.JPG

 


Edited by Peter Ceravolo, 20 January 2019 - 05:31 PM.

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#45 Peter Ceravolo

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Posted 20 January 2019 - 06:16 PM

Refinishing the paint on the Zeiss was a must, it was flaking off in places and fractured in most others.

As mentioned in an earlier post, the paint did not strip off easily with chemicals and is turns out body filler was used to smooth out welds and imperfections. It was a bigger job than expected, way past what I could or would want to deal with.

 

IMG_9052.JPG

 

Mark used 80 grit sand paper on a grinder to remove all the old stuff to reveal the bare metal. Even though he used a breathing mask and goggles, he could still sense that there was something nasty about the materials used in this East German telescope built sometime in the 70's. We didn't expect this, so I would encourage anyone else wanting to refinish these instruments to use the appropriate safety gear.

 

IMG_1566.JPG

 

The finished parts look like porcelain!

 

IMG_1589.JPG


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#46 Peter Ceravolo

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Posted 20 January 2019 - 07:51 PM

I thought I would expand a bit on the wire race bearings and disassembly of the RA housing/shaft.

 

I should start by saying we had no idea what we would find when we started removing panels and screws. It turns out the Zeiss is like a box of chocolates, open it up and it's full of surprises!

 

You start by removing the very nice RA circles. They are very pretty, but I really don't know how they are supposed to work. And that will be interesting when time comes to reassemble these parts.

 

IMG_2392.JPG

 

When we started removing these screws from this ring we really didn't know what we'd find:

 

IMG_2397.JPG

 

That last ring turned out to be half of the outer race of the massive bearing!

 

IMG_2400.JPG

 

In the image below you can see the ball bearings, the cage that keeps the balls separated, and the precision ground spacer that loads the assembled bearing when the screws are tightened.

 

IMG_2402.JPG


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#47 Peter Ceravolo

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Posted 20 January 2019 - 08:08 PM

Another surprise came when we were jostling the assembly about, the shaft almost fell out and that rear bearing came apart! That last ring, half of the our race of the bearing, is what held it all together.

 

Here is a diagram of the rear bearing assembly to make things clearer.

 

Wire bearing.PNG

 

The precision ground spacer must be custom to this particular unit, so I was careful to bag and identify the parts.

 

Here is a picture of the RA shaft housing, you can see the that the housing is actually part of the RA bearing! Upon close inspection you can see dents in the wire races simmilar to the ones found on the front RA bearing.

 

IMG_2491.JPG

 

I had never encountered wire race bearings before, and after much research, the implementation of the concept is in this telescope line is somewhat unusual. The great feature of the wire race is that the wire can be easily replaced if damaged. No easy way to do that with this set up. The wire is also round so the contact point is extremely small, thus the great potential for damage when an abrupt force is applied to the unit. When the telescope is being moved, you have to unload the bearings, remove the massive Dec housing and associated counterweights.

 

 


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#48 Max Lattanzi

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Posted 21 January 2019 - 06:38 AM

Peter,

 

I cannot but publicly thank you for the outstanding -- really outstanding -- job you have been doing on that instrument. 
Truly taking the bull by the horns, as said to you.
Thanks to you, I have a much clearer indication of what I shall be facing when this Spring/Summer I'll put my hands on it and open my own Easter Egg.

Again, heartfelt thanks (and Kudos, it goes w/o saying).

 

Cheers,

-- Max


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#49 nowhere

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Posted 21 January 2019 - 09:59 PM

Wow! Amazing work.

 

So this is the telescope I remember seeing in the observatory back in the 80's the two times I managed to get out there when it was open. When I visited more recently the current scope sure looked different from what I remembered... nice to know my memory was accurate!


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#50 Benach

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Posted 23 January 2019 - 10:49 AM

Small question: I won't be at the observatory for the next few days, but the housing, is that made of aluminium or steel?




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