Latest project - Dobsonian telescope


Here's a few pictures of the latest project. Probably a little off the beaten path:
http://home.earthlink.net/~nateperkins1/misc/astro/12dob/12dob.htm http://home.earthlink.net/~nateperkins1/misc/astro/12dob/12dob_pics.htm
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Nate: I like it. Very nice joinery and a thoughtful, simple design. I've done a few dobs up to 17.5" in "classic" style (read: "heavy") and appraciate your efforts to keep it light. A few questions: Does it balance well without weights? How does it break down for transport? Who did the mirror? Do you use a shroud? BTW: what is your 6" MN" I have an Intes 61 modified with a Crayford focuser and Parallax rings. It's superb--refractor quality if a bit heavy. Cool down may be an issue but it's worth it--I saw the horsehead nebula from West Texas last month..
Bob

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Bob Schmall wrote:

Hi Bob,
It's just a hair backheavy at the moment. Balances well with my heaviest eyepiece. I'm working on a sliding counterweight for it (copied from Highe and Plettstone again). At the moment I just stuff a couple of big knurled nuts inside the open end of the front trusses :-)
To break it down for transport, you unclamp the secondary platform, slide it off, and pull out the tubes. The mirror box and platform travel side by side in the back seat of my Saturn SL. I need to build some small poles to hold the secondary cage in place over the mirror box for transport.
The mirror came from Hardin Optical. It's a Guan Sheng (gulp). I worried a lot about the mirror, but it was a bargain at $400 and I figured I'd give it a try. Turns out that the star tests are right on (at least to the level of my expertise), and it's pushed 300x no problem and 400x intermittently.
I don't use any shroud. Hasn't made much effect so far. I'm working on a focuser end baffle.
I also have the Intes MN61 (the Orion black tube model). It's a good scope but as you say a bit on the heavy side with the mount and all. The views in the dob are beating the views in the MN61 (I guess this is proof that more aperture can trump finer optical quality).
Regards, Nate
p.s. Sorry to the other readers that this has already strayed from the topic of woodworking.

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Oh Nate, Now I am jealous! I have wanted to build a telescope but other projects keep jumping in front. Add do the fact I have no idea how to build one, but that's never stopped me before.
Yours looks terrific! I hope it sees as well as it looks! Did you grind your own mirror?
Dave
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Teamcasa wrote:

Hi Dave,
Naw, I bought the mirror. I'm not good enough to grind one. See the reply to Bob, above.
Regards, Nate
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Dave: There ae several vendors of high-quality mirrors listed in the back of Sky & Telescope and Astronomy magazines. You might also DAGS. As for scope design, Richard Berry & David Kriege's book on Dobsonian telescopes, and Berry's on several designs, can provide just about all the information you need. Again, see Sky & Tel's website for the books, or try Amazon.
Bob Schmall
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waiting my attention. The mirror making was the stopping point but now I believe quality mirrors are readily available.
Do you have a few pictures of the scopes you have built? I feel a new inspiration starting to grow! Thanks to you and Nate.
Dave
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Dave: Oh hell. I hate to step on your inspiration, but they're long gone. I got to the age when the strength and gymnastic levels required to use those things weren't there any more. Now I've gone over to the Dark Side--goto, a Mak-Newt and an SCT. Sob. To renew the inspiration, try sci.astro.amateur. Lurk for a while, then leap. Astromart has several forums that would be of interest to you, but it's tightly run so be sure that you register properly.
Bob
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Looks great, Nate. I've got an 8" pyrex blank waiting for some free time to try grinding my first mirror. I had my 3.5" refractor out last night showing Saturn, Jupiter & the moon to visiting cousins. A pox on the guy who pushed for street lights in our subdivision, then moved out a year later. Grrrrr.
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Nate Perkins wrote:

Nice woodworking.
You have answered some of my questions as I often mused on the idea of turning some of my woodworking skills to something useful. :-)
Enjoyed your site.
--
Will
Occasional Techno-geek
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Thanks, Will.
BTW, woodworking of all kinds is useful if you have a wife who wants something made for the house. SWMBO would say that my scope is far less useful than, say, a new buffet. :-)
Cheers, Nate
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Nate Perkins wrote:

Oh don't be silly -- of course I know that. :-) and <g>
It's why men become such consummate liars -- "Oh honey -- buy me that tool and I will make you a buffet (Right after I build my telescope (or whatever)." Right!
You must be young. Even someone as gullible as a wife who loves you catches on eventually -- given 20, 30 or 40 years say. <g>
So be careful out there.
We have reached the stage where her pupils contract when I mention "off topic projects" -- that's a bad sign. :-)
(A scope is so _much_ more useful. Sigh)
--
Will
Occasional Techno-geek
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This is the thing that got me interested in Wood Working in the first place! Oddly enough I still haven't built one... I just keep on using my trusty old 8" Celestron StarHopper.
That is a beautiful Scope!
mike

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