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Equipment Discussions >> ATM, Optics and DIY Forum

Pages: 1
drago
sage


Reged: 01/11/08

Loc: Latvia
dobsonian mount for 300PDS ?
      #6126260 - 10/09/13 01:45 AM

Hello!
Maybe anyone has already done to building dobsonian mount for sky-watcher 300pds OTA (12") ?
thinking about buil;ding that dob for these OTA.
think, plywood is a good material for that, but maybe anyone can say, what thickness is optiimal? 18 - 21 mm ?
i be happy for any suggestions and advices.
thanks


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eyepiecedropper
member


Reged: 12/31/11

Loc: aschaffenburg, germany
Re: dobsonian mount for 300PDS ? new [Re: drago]
      #6127596 - 10/09/13 06:26 PM

Hi, Iīll post some pics tomorrow. But be warned, itīs rather crude. No fancy notches. 15mm plywood. But it works nicely without backlash and motions are smooth.The az bearing is a lazy susan turntable unit out of plastic with some inherent friction. No overshooting. The alt bearing has a diam. of 400mm with belt strap on Teflon. It works surprisingly good, but all in all i wouldīt use it as reference ;-)

Regards, Martin


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drago
sage


Reged: 01/11/08

Loc: Latvia
Re: dobsonian mount for 300PDS ? new [Re: eyepiecedropper]
      #6128286 - 10/10/13 01:44 AM

ok, thanks, i be waiting.
looking also on some russian and english projects, and think as alt bearing try use a rollers wheels.
15 mm plywood not too thin \ flimsy?
i thinking about 18mm laminated from both sides. think a regulate alt friction like on a serial "skywatcher" dobs - via tighten construction and add friction via that...
sorry for my bad english...


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eyepiecedropper
member


Reged: 12/31/11

Loc: aschaffenburg, germany
Re: dobsonian mount for 300PDS ? new [Re: drago]
      #6130829 - 10/11/13 11:20 AM Attachment (14 downloads)

Hi, the dimensions:

alt bearing diam 360mm
groundboard 500x500mm
clearance between side parts: 400mm
thickness of plywood: 15mm (you can see that i stiffend the open end of the box with 20mm square pipe)
distance between ground board and center of alt bearing: 680mm, that gives you a clearance of 170mm between scope and ground board.


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eyepiecedropper
member


Reged: 12/31/11

Loc: aschaffenburg, germany
Re: dobsonian mount for 300PDS ? new [Re: eyepiecedropper]
      #6130830 - 10/11/13 11:21 AM Attachment (12 downloads)

next pic

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eyepiecedropper
member


Reged: 12/31/11

Loc: aschaffenburg, germany
Re: dobsonian mount for 300PDS ? new [Re: eyepiecedropper]
      #6130833 - 10/11/13 11:22 AM Attachment (9 downloads)

last one:

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Pinbout
Postmaster
*****

Reged: 02/22/10

Loc: nj
Re: dobsonian mount for 300PDS ? new [Re: drago]
      #6130912 - 10/11/13 11:56 AM

Quote:

i be happy for any suggestions and advices.





love the astrogoods design concept with his clamshell rings.


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drago
sage


Reged: 01/11/08

Loc: Latvia
Re: dobsonian mount for 300PDS ? new [Re: Pinbout]
      #6131249 - 10/11/13 02:21 PM

eyepiecedropper:

Danke shon!
i see, you not using azimuth bearing at all? what observations can possible without az axis? :-O
and why groundboard is 50x50 cm, if clearance between walls is only 40 cm?

Edited by drago (10/11/13 02:22 PM)


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eyepiecedropper
member


Reged: 12/31/11

Loc: aschaffenburg, germany
Re: dobsonian mount for 300PDS ? new [Re: drago]
      #6132485 - 10/12/13 05:43 AM

hi, as i said: this thing works, nothing more. usually all of my scopes are eq-mounted.
the az-bearing is a turntable unit.
http://ecx.images-amazon.com/images/I/41djLlBOYhL.jpg

You want to build a nice looking one:

http://www.deepsky-brothers.de/Rockerbox-GSO.htm
http://www.astrotreff.de/topic.asp?TOPIC_ID=152694
http://www.astrotreff.de/topic.asp?ARCHIVE=true&TOPIC_ID=106315
http://www.astrotreff-deep-sky.de/ATDS_postst4182_AstroBastelstunde-Teil1.aspx
http://dobstuff.com/customrockerbox.htm

Regards, Martin


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eyepiecedropper
member


Reged: 12/31/11

Loc: aschaffenburg, germany
Re: dobsonian mount for 300PDS ? new [Re: eyepiecedropper]
      #6132555 - 10/12/13 07:42 AM

some instructions:

http://stellafane.org/tm/dob/mount/rockerbox.html
http://www.instructables.com/id/Homemade-125-inch-Dobsonian-Telescope/?ALLSTEPS


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drago
sage


Reged: 01/11/08

Loc: Latvia
Re: dobsonian mount for 300PDS ? new [Re: eyepiecedropper]
      #6134362 - 10/13/13 06:16 AM

thank you!

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