Build a 6" or 8" dob

[Per167]

Hi all,

I have recently been playing with the idea of building my own telescope. In the future a big truss dob is very tempting but the way my life looks at the moment - wife, two small children and a full time job - I don't want to rush into something I can't finish. I am therefore aiming more towards a first, more reasonable project to practice and learn.

I have so far only invested in some books:

- The Dobsonian Telescope: A Practical Manual for Building Large Aperture Telescopes (Kriege and Berry)

- How to Make a Telescope (Texereau)

- Build Your Own Telescope (Berry)

And now for the question: is there a big difference in building an 8" compared to a 6" dob? I am mainly considering the grinding and figuring of the mirror, which I would like to do myself. As you can see from my sig I already have an 8" Skywatcher Flextube. The plan for the rest of the scope is to build a small scale truss tube - kind of a small scale model of the large scope I might build sometime in the future.

Any other comments from those of you who have undertaken this kind of project is very welcome!

[marcopolo]

Definitely 8in. as it will take you the same length of time to make as the 6in anyway. Just be prepared for serious labour time of 150+ hours to grind, build tesing aparatus, test, figure, test, correct. test, correct, test, regrind, refigure, retest, scream, retest, scream some more, shout at the walls and the dog, refigure....rinse and repeat, sign divorce papers, re-marry, restart mirror making project then wait for postman to deliver your silvered mirror that you made from optical company and the flat you ordered and even then you've still to build the actual scope!! Or// you could spend 250 Euro on a finished mirror set and build a telescope instead.

Marco

[Per167]

I get your point, Marco. I will definitely think twice before starting a grinding project but a large part of the appeal is to do the whole setup myself. I'm really fascinated that you can (after 150+ hours of work, that is) actually make something like a telescope mirror without any advanced machinery. Being an engineer that is hard to resist.. And I already have an 8-incher so I'm in no hurry to finish it.