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1965 Cave 10" f/16 Dall-Kirkham OTA

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326 replies to this topic

#26 PiSigma

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Posted 04 March 2011 - 01:31 PM

Nice acquisition Tim!

I only have one Cave Cass in my mirror registry. It is an 8" from 1974 and has a "conventional" Cave serial number.

#27 clintwhitman

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Posted 04 March 2011 - 02:01 PM

Tim A quick note, I have a friend that is an engineer at L3Com Tinsley Brashear, You might recall he purchased my old old 4" Tinsley refractor. I sent him photos of the numbers and asked for his review. He has two large Tinsley Cass telescopes in his collection..Cross you fingers!!!
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#28 tim53

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Posted 04 March 2011 - 02:19 PM

Thanks, Clint!

phalanges crossed!

-Tim.

#29 tim53

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Posted 05 March 2011 - 02:16 PM

Okay, I met my deadline (on my birthday, no less!), got a good night's sleep, am coffeed up and rarin' to go!

more pics:

The Unitron focuser also serves as the primary baffle support! Who'da thunk it?

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#30 tim53

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Posted 05 March 2011 - 02:19 PM

And there's a whole herd of backfocus, especially when you pull the drawtube all the way out! (which also retracts the 'baffle'). Here, I haven't even racked the focuser out...

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#31 tim53

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Posted 05 March 2011 - 02:21 PM

Secondary looks to be in decent shape, though it's a bit dirty. I'll have to hunt for my really dinky allen wrenches to take the 2ndary baffle off and get at the mirror to see if there's anything written on it, but I'll do that in a bit.

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#32 DAVIDG

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Posted 05 March 2011 - 02:27 PM

Tim,
The local high school also has 10" Cave DK that I have been working on. You should replace the baffle with a fixed position one. When you focus the position of the tube moves and either cuts into the light cone coming from the secondary if it is too close to it or if it is to far back, allows sky light to enter into the focal plane and fog the back ground.

- Dave

#33 tim53

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Posted 05 March 2011 - 02:28 PM

60x700 Mayflower guidescope

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#34 tim53

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Posted 05 March 2011 - 02:29 PM

with broken cover over the pinion gear:

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#35 tim53

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Posted 05 March 2011 - 02:32 PM

This guidescope is almost identical to the unmarked one I got with the 4.25" f/5.5 I bought from Ron Ezra while I was working at Meade in 1979. Ron had made the 4.25" while at Cave, so he probably got the guidescope at the same time. I suppose I could either use that guidescope until I find a replacement pinion gear cover for this one. I like the fact that this one is labeled. And the cell is a bit different looking than my unbranded one. Focus knobs are identical, though.

-Tim.

#36 tim53

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Posted 05 March 2011 - 02:39 PM

finder and guidescope brackets are sorta wrinkly bronze/brown painted. I couldn't see any sign of black underneath the paint where it's chipped, but I can't believe they weren't wrinkle black to match the backplate and stuff. I like that, even in 1965, the adjustment screws are tipped with nylon or teflon.

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#37 tim53

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Posted 05 March 2011 - 03:40 PM

Okay, so the secondary also has this number:

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  • 4428263-2ndary_number.jpg


#38 tim53

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Posted 05 March 2011 - 03:41 PM

Coatings are a little better condition than on the primary, but I can see through them, and they are a bit dirty:

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  • 4428268-2ndarycoating.jpg


#39 tim53

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Posted 05 March 2011 - 03:45 PM

This is funny, the secondary hub has a "3" on it. But this reminds me of the numbers on my 8" lightweight deluxe, and probably just means this is the third telescope on the bench being assembled. Note that the number was writ before the central hole was drilled for the mounting rod...

-Tim.

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#40 tim53

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Posted 05 March 2011 - 07:06 PM

I made a saddle plate out of 3/4" chinese birch plywood and solid birch 1x stock. Here I'm checking the radius fit to the tube:

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#41 tim53

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Posted 05 March 2011 - 07:07 PM

it fits! So I bolted it to the tube using 3/8-16 bolts, lock washers and nuts.

NExt, I put all the components in/on the tube to find the balance point:

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#42 tim53

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Posted 05 March 2011 - 07:13 PM

what's weird is that Cave apparently put the guidescope just left of top and the finder a lot to the right of the top. Maybe it balances that way?

Here, I've marked the balance point on the saddle plate with an "X", just above the 2nd screw from the left.

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  • 4428709-balancept.jpg


#43 tim53

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Posted 05 March 2011 - 07:16 PM

You can see it balances close to the mirror end, which is what I found with my 12.5" Cass as well. That's cool. It means the eyepiece won't be moving around a whole lot!

Okay, going to put it aside for a while so we can go out to dinner early. I'll put the studs in the saddle plate for attaching to the Tak saddle plate (decided to use the thing, rather than buy another Cassidy saddle, since the one for the bigger mount is on the Em-500).

-Tim.

#44 GeneT

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Posted 05 March 2011 - 10:05 PM

Enjoyed the posts!

#45 tim53

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Posted 06 March 2011 - 12:19 AM

Thanks!

Okay, just came from fiddling with it!

Here it is on the NJP. Perfect size mount for this scope!

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#46 tim53

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Posted 06 March 2011 - 12:22 AM

too

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#47 tim53

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Posted 06 March 2011 - 12:27 AM

I got it together after we went to dinner, so I did the best I could in the dark with the collimation. It was okay, but not optimal.

Contrast was pretty good - though I suppose such a huge secondary (30%) helps keep stray light out of the primary baffle.

-Tim.

#48 Bill Griffith

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Posted 06 March 2011 - 07:21 AM

Congratulations Tim!
Please let me know the projects you can't get to! :D You have some GREAT projects!
Anyway, I just popped in while getting some coffee on an observing session, (casual Messier Marathon)
On a side note on one of your earlier posts on this thread on the primary's and secondary's coating. Metal likes to be thin in vacuum deposition, this actually gives a higher reflectance. Even with a dielectric protected overcoat the transmission would be nil but if you hold a 60 watt or even a bright flashlight behind an optical mirror you could detect the light source. Did I mention this isn't intuitive?
Thicker coatings are deposited most of the time so customers don't complain and want a refund or a do over.
Lastly, Happy Birthday!
Bill

#49 Rich (RLTYS)

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Posted 06 March 2011 - 07:48 AM

Tim

Nice scope LOL.

Rich (RLTYS)

#50 clamchip

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Posted 06 March 2011 - 10:58 AM

Looks great Tim.

Quote from the Cave catalog for this scope:
"Designed and manufactured for the observer desiring maximum resolution and definition for planetary and lunar observing".

Specs show 2.9" secondary and over 4000mm focal length.
Is it possible the extremely high focal ratio f16 can cancel out and overcome the 30% CO?
Just wondering why you didn't need CPR after 1st light, collimation is critical with this design? and probably getting the secondary exactly on axis.

Robert


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