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Need help removing the mirrors on a C11 Orange Tube

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#1 John Higbee

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Posted 21 April 2019 - 09:20 PM

Just got a C11 Orange Tube in rough condition (telescope had been stored outside under a thin tarp for years, without a corrector dust cover, and the corrector plate was opaque with dirt). 

 

After several days using Dr. Clay's cleaning solution and a lot of water, corrector is clean.  Secondary, though, has coating degradation all around the rim of the mirror...didn't touch it...definitely needs stripping and recoating. 

 

Primary looks fair, (minute amounts of degradation around the mirror rim)  but am thinking that I'll send it in with the secondary and get both recoated at once (scope is close to 30 years old, so I'd have to do it soon in any case).

 

My question...where can I get instructions for dismounting the primary and the secondary?  Have tried to unscrew the secondary holder ring from the holder itself...it's not budging.

 

Thanks in advance, John



#2 D_talley

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Posted 21 April 2019 - 09:32 PM

You need to read this:

 

https://www.cloudyni...et#entry8632792

 

and you need to read this.  There were no replies:

 

https://www.cloudyni...ting +celestron


Edited by D_talley, 21 April 2019 - 09:35 PM.


#3 John Higbee

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Posted 22 April 2019 - 05:37 AM

You need to read this:

 

https://www.cloudyni...et#entry8632792

 

and you need to read this.  There were no replies:

 

https://www.cloudyni...ting +celestron

Appreciate the fast response!  Nice job on the old C14...got one of those several years ago after it had been left in a shed for a few years...luckily the optics were still usable without major overhaul.

 

After readings the references you provided, I'll leave the primary "as is"...but still need to have the secondary recoated.  The problem is getting the secondary cell out of the corrector plate.  Uncle Rod (Mollise) talked about having to eventually put the corrector cell assembly on an SCT he was working on through several freezing/heating cycles before he could remove the cell...he's braver than I am (at least for now).

 

thanks, John



#4 KerryR

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Posted 22 April 2019 - 08:08 AM

Why remove the secondary housing from the corrector? It should be adequate to remove the 3 collimation screws, and the central screw if present. The holder would stay in the corrector.



 



#5 macdonjh

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Posted 22 April 2019 - 12:48 PM

Why remove the secondary housing from the corrector? It should be adequate to remove the 3 collimation screws, and the central screw if present. The holder would stay in the corrector.



 

+1

 

Also, call a couple of coating companies.  I think a friend of mine had a C11 primary mirror recoated without removing the mirror from the aluminum "sled" it is glued to.  I didn't think that would have been possible, but if my memory is correct, it was possible: he did it.  If it can be done, all you have to do is remove the snap ring near the end of the primary baffle tube, then use the focuser knob to move the primary mirror as far forward as it will go and lift the assembly out of the OTA.



#6 John Higbee

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Posted 22 April 2019 - 03:47 PM

Re: the secondary - of course!!! (sound of hand slapping forehead). 

 

Re: the primary - will contact my coating company and see if they can do it that way!

 

KerryR, Macdonjh...thanks for the advice!

 

John



#7 Stevegeo

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Posted 22 April 2019 - 07:30 PM

I worked for a company here in upstate ny that coated many optical and consumer items with aluminum...

Head lights , tail lights, stop , mirrors. Etc.

 

There are two methods ( maybe more), that coat glass,  one method is flash aluminizing..

A simple explanation a part is put in a chamber  pumped down to near zero vacuum. A Tunston  element which looks like a large lightbulb element  is loaded with a sliver of pure aluminum  inside the loop.  A high voltage / current is introduced to this  element instantly vaporizing the aluminum depositing to the target.  The chamber is normalized and part removed with gloves hands.... shiny...   this is how headlights, plastic and glass are done. 

 

The other is a bit more complicated, but higher quality. Cathartic Arc.. a clean part is put on jig or fixture  placed inside a chamber under extreme  vacuum,  higher then space itself  the parts are negatively  charged inside, and a target metal is positively charged, the part passes in front of the target , positive metal is dissipated to the negative and the part is plated.

This process (simplified here )  is used from everything  from  titanium nitride coated drill bits and tooling, to gold plating jewerlery. And glass. Though not a conductor, can be done this way ,but may take many passes..

 

This process can bring the plating process down to  a single molecule...  there is more to this process,  such as exotic gasses introduced. Various voltages,  and frequencies.    

Flash method is obviously cheaper , and usually does bulk items. The Cathartic Arc for extreme quality, precision, or metals other then aluminum  or very high quality aluminum parts.

Both methods can be masked...

 

Flashlishlight reflectors use flash ( bulk and speed)

Headlights use either...

Tooling usually Cathartic arc.




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