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Dovetail installation

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#1 m00nless

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Posted 13 September 2017 - 03:27 PM

Which of the screws on either side (corrector and mirror) of an Ultima 11 optical tube can be used to install a dovetail?


Edited by m00nless, 13 September 2017 - 03:53 PM.


#2 m00nless

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Posted 30 September 2017 - 04:31 AM

I think a better question would be which dovetail is compatible with an Ultima 11? And do more recent optical tubes use a different configuration or would a dovetail fit all C11s regardless age?



#3 Phil Wheeler

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Posted 30 September 2017 - 01:12 PM

You might want to Google something like 'ultima 11 dovetail installation'.  One hit I got was this thread:

 

https://www.cloudyni...-report-update/

 

This might also be of interest: http://uncle-rods.bl...g-deforked.html

 

And there are others.



#4 m00nless

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Posted 01 October 2017 - 01:52 AM

You might want to Google something like 'ultima 11 dovetail installation'.  One hit I got was this thread:

 

https://www.cloudyni...-report-update/

 

This might also be of interest: http://uncle-rods.bl...g-deforked.html

 

And there are others.

Already seen the above and some other threads that did not help much.



#5 Phil Wheeler

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Posted 01 October 2017 - 01:03 PM

Then I'd try an email to Rod Mollise or a post at his SCT Users Group https://groups.yahoo...s/sct-user/info



#6 carolinaskies

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Posted 01 October 2017 - 03:57 PM

Which of the screws on either side (corrector and mirror) of an Ultima 11 optical tube can be used to install a dovetail?

On the Ultima series typically the dovetail bars are attached via the holes 90* from the fork arms/focuser position.  However you can attach to any of the holes that line up front to back with the correct dovetail.  The bars built for these OTAs attach via one screw mount up front and 2 screw mounts on the back and use riser blocks that bolt to the OTA first and then you bolt the dovetail to the risers.  

I have an Ultima 8 I'm in the process of deforking/dovetailing and making my own riser blocks for a dovetail bar I bought on CN.  

 



#7 m00nless

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Posted 04 October 2017 - 12:36 PM

What Vixen dovetails are currently available and compatible with a C11? I don't think Celestron makes one. ADM does, but what other choices do I have?



#8 DuncanM

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Posted 04 October 2017 - 02:18 PM

What Vixen dovetails are currently available and compatible with a C11? I don't think Celestron makes one. ADM does, but what other choices do I have?

Losmandy makes D series plates that are drilled to fit C-11s and these are a better choice for an OTA of the C-11's weight.  What mount are you going to use? 



#9 m00nless

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Posted 05 October 2017 - 12:40 PM

I am looking for a Vixen type dovetail as this is what the mount I plan to use accepts. Will a dovetail for a current C11 also fit an Ultima 11? Are the holes on optical tubes the same?



#10 mclewis1

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Posted 05 October 2017 - 02:40 PM

If you have a choice don't use a Vixen dovetail bar on a C11. Look at upgrading your mount's saddle if possible.

 

If you do use a Vixen dovetail don't go cheap. ADM or Losmandy make a nice solid Vixen bar that mounts with radius blocks ... don't use the Celestron one piece orange extruded Vixen/CG-5 compatible bar.

 

If you do use a Vixen dovetail of any type keep your C11 as light as possible. Stick with a small finder and 1.25" accessories or if using a camera for solar system work keep to the lighter smaller sensor models. Don't bother with 2" accessories and/or binoviewers, and no piggyback options, etc. It's not like any of these will not work but you'll end up with weight creep and eventually really start to notice movement in your mounting setup.

 

You'll simply be happier in the long term if you spend the money up front for a better more robust mounting setup (read - D type of dovetail plate from a good supplier in a good D type saddle on your mount).



#11 mclewis1

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Posted 05 October 2017 - 02:50 PM

About the mounting bolts.

 

While the Ultima C8 has single bolt holes on the front corrector cell the larger C11 I believe only has bolt pairs (threaded bolt holes at 12, 3, 6, and 9 o'clock positions, with each being a pair of bolts 1.75" apart filled with raised head bolts). What you don't want to touch are the bolts with flush heads that are in singles and mounted closer to the tube itself, those are used to attach the tube to the front and rear corrector cells.

 

With any work to attach new gear (dovetails, finders, etc.) to the rear cell please make doubly certain that the mounting bolts don't protrude very far into the interior of the rear cell. You want to make certain that the ends of the bolts don't come into contact with the edge of the primary mirror as it's racked through it's focus range. It's always a really good idea to take a good close look at those new bolt locations from the front of the scope as you carefully run the focuser through it's full range (may require a second person to help here), and if you feel any binding stop immediately and re check those bolts.




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