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Picked up a C11 vintage 1990

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#1 bremms

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Posted 08 November 2012 - 01:24 PM

Just picked up a C11 from black tube with black crackle cell and mount. Scope is scuffed up and the paint is coming off on of the fork legs. The corrector was not installed correctly and the optics need a bit of cleaning..

Good.. Mechanically very sound
Optics are in good shape after cleaning.
Got it at a good price.

Bad.. Tube is scuffed up and scratched but not dented(good).
A previous attempt at cleaning left OTA in a funny state.

Problems I found with the OTA
1. No cork on the lip of the cell.. Just glue. corrector was set ON the glue. *BLEEP*??
2. New cork on the retainer was put on very hap hazard.
3. Retaining ring screws were TIGHT...
4. No grease on the mirror baffle!! It was cleaned up very well except for two blobs of grease on the side of the mirror???

I'm thinking the scope was taken apart to be cleaned/ serviced and was put back together at a later date. by someone who didn't really know what they were doing.

It's all apart and I cleaned the primary. Coating looks very good. Corrector has a bit(lot) of glue around the edge that needs acetone for removal. Picked up some nice 1/16" cork automotive gasket for the corrector cell and retaining ring.

I have three different greases for the baffle tube.
Slick 50, Mobil 1, and vacuum grease. Slick 50 has NO odor like the vacuum grease but is a much better lube. The Mobil 1 is nice but does have some odor.
I'll take some pictures of the scope and process this evening.

#2 bremms

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Posted 09 November 2012 - 07:02 AM

Finished getting the scope back together . Everything went well, took it out for a star test. The secondary wouldn't collimate. At first two of the screws were bottomed out. It wasn't pivoting. Went inside, took the corrector back out. The little cast button is about the same size as the pivot hole in the secondary, the very edge of th button had been stripped down flat. So the secondary was sitting flat against cell. I need to make a new little button for the cell. ( brass instead of plastic) I'd get that fancy Starizona cell, but it costs nearly as much as my whole scope.

#3 bremms

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Posted 09 November 2012 - 12:30 PM

Took 30 minutes of quality time to figure out what I need to do with the secondary situation. Turns out the secondary has some adjustment (not much). But the secondary and holder is thicker by about 1mm on one side, Out of the range of adjustment of the cell. The cell is "fine" the cast part has a centering button not much adjustment since the part that the holder sits on is only about 0.5mm high.
I made a little washer to fit over the centering button about 1mm thick. That will give plenty of adjustment range for the secondary. The cell gets distorted at the screws and the range of adjustment gets smaller and smaller.

#4 bremms

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Posted 10 November 2012 - 01:17 AM

Installed the little spacing ring/washer. Worked like a charm.
Did a rough star alignment. Images looked pretty good, inside and outside focus rings looked pretty good alignment wasn't perfect, but close. One issue is the grease on the baffle tube is too heavy and thick. The foucusing is very stiff. This scope has a very tight baffle tube clearance. No image shift at all. Still needs a good bit of mechanical work.

#5 albert1

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Posted 10 November 2012 - 03:09 AM

Congrats Marc. Sounds like a nice find. The work you're doing should make this a very rewarding scope. I've completely disassembled a few for an overhaul and it's amazing what a little cleaning, relube and adjusting will do for these old beauties. Let's see some pics.

#6 bremms

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Posted 10 November 2012 - 08:24 AM

Finally found the camera.

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#7 bremms

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Posted 10 November 2012 - 08:25 AM

And yes, the forks are reversed.

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#8 bremms

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Posted 10 November 2012 - 08:27 AM

They are reversed on the drive base not the ota

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#9 bremms

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Posted 10 November 2012 - 08:28 AM

Another...

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#10 sgorton99

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Posted 10 November 2012 - 08:29 AM

Nice project, that is a big scope!

#11 bremms

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Posted 10 November 2012 - 04:13 PM

Yea, that Celestron Big Wedge is MASSIVE, all of 40 lbs. The scope is bigger than I thought... Much more massive than a C8.
Going to try and set it up this evening on something sturdier than the deck table.

#12 bob midiri

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Posted 10 November 2012 - 06:56 PM

until I got my C14 tripod I set my Classic orange C14 0n a workmate bench. i placed a double tickness of 3/4 ply and screwed it into the workmate bench. Then put some sand bags on the folded workmate legs. It worked like a charm (I also then screwed the wedge into the doublethickness plywood. Bob

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#13 Joe Cepleur

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Posted 10 November 2012 - 07:46 PM

Bremms, you are going to love that scope. Nothing there that can't be fixed! Please keep posting your progress.

Bob, great to see those giant, sand-cast forks! Wonderful old scope.

Amazing that these are essentially the same telescope made some years apart, wearing different livery. I'm planning a trip to see a blue-and-white C10 in a rooftop observatory. Watch for the thread!

#14 bob midiri

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Posted 10 November 2012 - 07:49 PM

looking forward to that thread Joe!!

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#15 bremms

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Posted 11 November 2012 - 04:48 PM

That's funny, been putting mine on the deck table with smoe plywood and c-clamps. Tweaked the collimation and am happy with the optical performance. Jupiter looked good, I could see the "pink" spot move in between sessions. Thought the scope might have a little astigmatism, but it seems related to cooling and looking over the neighbors house. It was not there very much.

#16 bremms

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Posted 21 November 2012 - 10:30 PM

Fixed a few more things on the C11. Removed the mirror to take out the too stiff slick 50 grease.. (too much as well)
Foscusing was very stiff and had a lot of hysteresis. Used just a dab of Mobil 1 grease smeared around the tube (just a little) VERY nice. Great feel now. No noticeable shift. Regreased the dec bearings, made a weight for the counterweight bar, adjusted the worm gear for backlash, polished the tube and just cleaned up a bunch of things.
It was a real joy to use this evening. Problem is,seeing is about a 2 right now. Only had to do a tiny tweak to get the collimation right in line. The C11 is really coming together. Never been a big Celestron fan, but I really like this C11. It needed some love has good optics and has personality.
I don't even want to paint the scratched tube.

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#17 bremms

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Posted 21 November 2012 - 11:25 PM

Cleaned up a bit

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