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My new main instrument: a 16" truss Dobsonian

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#1 Roel

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Posted 04 November 2012 - 02:33 AM

Nearly two months ago I started building my biggest telescope so far: a 16" Dobson. I used a GSO primary and a Orion UK 3" secondary (18% obstruction)

I combined several designs I found on the internet to make the scope relatively lightweight but solid, and very important: the primary mirror box had to be a closed box to be able to use a Di Lio type cooling system.

It all worked out as planned and yesterday I took the telescope out under the streetlights :ooo: for its First Light, mainly to test the mechanics.

I have not yet installed the fan, so the thick mirror was far from ambient temperature. The optics could therefore no be judged, but the overall smoothness of the telescope's movements turned out to be just perfect! While moving the telescope around with just two fingers it's hard to believe your moving a 60lb mass.

The eyepiece height is 167cm, so I can easily look through the scope at zenith without having to use a step.

The scope is not finished yet. I still have some painting to do, and the primary cooling/ secondary heating has to be installed. But allready I have a working 16" telescope now!

Can't wait to take it out to rural sites for some serious deepsky fun!

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#2 Roel

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Posted 04 November 2012 - 02:34 AM

Primary mirror box:

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#3 Roel

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Posted 04 November 2012 - 02:35 AM

First light!

(More pictures of the building process can be found here: http://www.roelblog....-truss-dobson/)

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#4 planet earth

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Posted 04 November 2012 - 03:18 AM

That's a great looking scope, nice work
Enjoy :)
Clear Skies
Sam

#5 reiner

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Posted 04 November 2012 - 04:48 AM

Looks like a great telescope, well executed.

Do you use a baffle on the upper cage, opposite the focuser?

#6 Roel

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Posted 04 November 2012 - 06:09 AM

Hello Reiner! I must say 80% of the design is from your excellent website. Especially the descriptions of how to make the lower truss connectors, and how to poperly place the altitude bearings were very helpful!

Another inspiration for this telescope is the Canopus model by Sumerian Optics, mainly for its looks.

I do use a light baffle. It's barely visible in the "first light" picture, but you might be able to see it if you move your screen a little bit.

#7 starman345

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Posted 04 November 2012 - 06:18 AM

Nice looking telescope, I really like the altitude bearing design with the holes and also the stiffener between them

#8 Tim C

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Posted 04 November 2012 - 07:42 AM

Very nice scope! Looks very functional and very handsome - great job. Interested to know how the optics perform.

Tim

#9 Pinbout

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Posted 04 November 2012 - 08:58 AM

that is a very attractive scope, something to be very proud of.

#10 Achernar

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Posted 04 November 2012 - 09:16 AM

In a word, the work you did is superb, and that is a good looking telescope too. No doubt the views will be as good as the mechanics. :bow: I would definitely be thinking about adding digital setting circles to it, you will never run out of things to see with a 16-inch.

Taras

#11 rik ter horst

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Posted 04 November 2012 - 12:10 PM

Keigaaf Roel!! Really good looking! Next, an equatorial platform??
Cheers,
Rik

#12 TileArt

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Posted 04 November 2012 - 07:31 PM

That is a beautiful dob Roel! Well done.

#13 Dave O

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Posted 04 November 2012 - 07:59 PM

Yes, a fine looking instrument indeed! I particularly like the method used to attach the lower portions of the trusses and the spacer on the alt-bearings. Very nice design and construction. Thanks for sharing. :)

#14 Mr Magoo

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Posted 04 November 2012 - 08:40 PM

Well done Roel! I love the simplicity of the design. What is the focal length?

#15 tcmzodiac

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Posted 04 November 2012 - 09:34 PM

Gorgeous!!!!

#16 Roel

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Posted 16 November 2012 - 10:43 AM

Update!

The telescope is now completely finished. I painted black all the parts that are visible through the focuser. For blackening the 20mm trusses I used 22 shrink sleeve.

Wednesday evening the Dob got its real first light under a dark sky. It was a perfect evening: a nice magnitude 6 moonless sky and great seeing. The view of Jupiter at 360x was the best I ever got through a telescope. It blew me away! Deepsky was amazing as well, a huge difference with my previous 12" Dobson. Everything works fine: the movements, the secondary mirror heating, the primary mirror fan. Me = happy!

The photo's were made in the afternoon previous to this observing night. Looking at that blue sky you can imagine that I couldn't wait till sunset!

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#17 Roel

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Posted 16 November 2012 - 10:45 AM

The inside of the mirror box with the "Mauro Da Lio" baffle, 40mm above the surface of the primary. On the right you can see one of the twoo collimation knobs:

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#18 Roel

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Posted 16 November 2012 - 10:46 AM

The secondary cage:

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#19 Roel

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Posted 16 November 2012 - 10:48 AM

Another one, showing the complete setup. The weight of the total telescope is 28 kg (62 pounds). This includes the 12kg (26 pounds) heavy primary:

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#20 Roel

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Posted 16 November 2012 - 10:50 AM

Three vane spider, made out of hacksaw blades. One vane is slightly thickened by the wire for the secondary heater:

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#21 Roel

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Posted 16 November 2012 - 10:51 AM

Last picture:

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#22 tcmzodiac

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Posted 16 November 2012 - 10:52 AM

Looks FANTASTIC!!!! What primary did you use?

#23 Pinbout

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Posted 16 November 2012 - 10:52 AM

Another one, showing the complete setup.


that's an awesome photo of a work of art. :grin:

#24 Mirzam

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Posted 16 November 2012 - 10:55 AM

Really nice looking telescope. I like the shrink sleeve idea. Need to look for some here.

JimC

#25 Roel

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Posted 16 November 2012 - 11:00 AM

What primary did you use?

I used a second hand 16" f/4.5 GSO primary. It has been Hilux recoated by Orion Optics UK. The secondary mirror is from Orion UK 75mm (18,5% obstruction) , also with Hilux coating.






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