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Equipment Discussions >> ATM, Optics and DIY Forum

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Roel
professor emeritus


Reged: 04/22/07

Loc: Deventer, The Netherlands
My new main instrument: a 16" truss Dobsonian new
      #5503360 - 11/04/12 02:33 AM Attachment (136 downloads)

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 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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Roel
professor emeritus


Reged: 04/22/07

Loc: Deventer, The Netherlands
Re: My new main instrument: a 16" truss Dobsonian [Re: Roel]
      #5503362 - 11/04/12 02:34 AM Attachment (87 downloads)

Primary mirror box:

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Roel
professor emeritus


Reged: 04/22/07

Loc: Deventer, The Netherlands
Re: My new main instrument: a 16" truss Dobsonian new [Re: Roel]
      #5503363 - 11/04/12 02:35 AM Attachment (73 downloads)

First light!

(More pictures of the building process can be found here: http://www.roelblog.nl/2012/10/bouwverslag-406mm-f4-5-truss-dobson/)


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planet earth
Pooh-Bah
****

Reged: 09/07/10

Loc: Ontario Canada
Re: My new main instrument: a 16" truss Dobsonian new [Re: Roel]
      #5503378 - 11/04/12 03:18 AM

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


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reiner
sage
*****

Reged: 09/28/05

Loc: Freiburg, Germany
Re: My new main instrument: a 16" truss Dobsonian new [Re: Roel]
      #5503403 - 11/04/12 04:48 AM

Looks like a great telescope, well executed.

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


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Roel
professor emeritus


Reged: 04/22/07

Loc: Deventer, The Netherlands
Re: My new main instrument: a 16" truss Dobsonian new [Re: reiner]
      #5503436 - 11/04/12 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.


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starman345
Wait, I'm Thinking
*****

Reged: 07/06/10

Loc: New Brunswick, Canada
Re: My new main instrument: a 16" truss Dobsonian new [Re: Roel]
      #5503442 - 11/04/12 06:18 AM

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

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Tim C
Pooh-Bah
*****

Reged: 11/11/07

Loc: Marietta, GA
Re: My new main instrument: a 16" truss Dobsonian new [Re: starman345]
      #5503495 - 11/04/12 07:42 AM

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

Tim


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Pinbout
Postmaster
*****

Reged: 02/22/10

Loc: nj
Re: My new main instrument: a 16" truss Dobsonian new [Re: Roel]
      #5503579 - 11/04/12 08:58 AM

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

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Happy Birthday Achernar
Postmaster
*****

Reged: 02/25/06

Loc: Mobile, Alabama, USA
Re: My new main instrument: a 16" truss Dobsonian new [Re: Roel]
      #5503611 - 11/04/12 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. 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


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rik ter horst
sage


Reged: 11/01/10

Loc: Ewer, the Netherlands
Re: My new main instrument: a 16" truss Dobsonian new [Re: Achernar]
      #5503835 - 11/04/12 12:10 PM

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


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TileArt
member
*****

Reged: 09/13/12

Loc: Fort Collins, Colorado
Re: My new main instrument: a 16" truss Dobsonian new [Re: rik ter horst]
      #5504435 - 11/04/12 07:31 PM

That is a beautiful dob Roel! Well done.

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Dave O
sage
*****

Reged: 12/21/11

Loc: Sri Lanka
Re: My new main instrument: a 16" truss Dobsonian new [Re: TileArt]
      #5504470 - 11/04/12 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.

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Mr Magoo
Carpal Tunnel
*****

Reged: 11/05/05

Loc: Franklin, Indiana
Re: My new main instrument: a 16" truss Dobsonian new [Re: Roel]
      #5504521 - 11/04/12 08:40 PM

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

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tcmzodiac
professor emeritus


Reged: 11/11/11

Re: My new main instrument: a 16" truss Dobsonian new [Re: Mr Magoo]
      #5504616 - 11/04/12 09:34 PM

Gorgeous!!!!

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Roel
professor emeritus


Reged: 04/22/07

Loc: Deventer, The Netherlands
Re: My new main instrument: a 16" truss Dobsonian new [Re: tcmzodiac]
      #5522629 - 11/16/12 10:43 AM Attachment (33 downloads)

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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Roel
professor emeritus


Reged: 04/22/07

Loc: Deventer, The Netherlands
Re: My new main instrument: a 16" truss Dobsonian new [Re: Roel]
      #5522634 - 11/16/12 10:45 AM Attachment (34 downloads)

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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Roel
professor emeritus


Reged: 04/22/07

Loc: Deventer, The Netherlands
Re: My new main instrument: a 16" truss Dobsonian new [Re: Roel]
      #5522639 - 11/16/12 10:46 AM Attachment (29 downloads)

The secondary cage:

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Roel
professor emeritus


Reged: 04/22/07

Loc: Deventer, The Netherlands
Re: My new main instrument: a 16" truss Dobsonian new [Re: Roel]
      #5522644 - 11/16/12 10:48 AM Attachment (25 downloads)

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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Roel
professor emeritus


Reged: 04/22/07

Loc: Deventer, The Netherlands
Re: My new main instrument: a 16" truss Dobsonian new [Re: Roel]
      #5522647 - 11/16/12 10:50 AM Attachment (31 downloads)

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

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