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Thread: Building a Newtonian

  1. #1 Building a Newtonian 
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    Has anyone done it and do they have tips?


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  3. #2 Re: Building a Newtonian 
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    Quote Originally Posted by C_Sensei
    Has anyone done it and do they have tips?
    I've built a number of truss dobsonians. What exactly are you trying to do?


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    Are you making it from scratch? ie. Grinding your own mirror? I would say not just on this part, but on the whole project, the best advice is slow and steady. Don't cut corners. Like don't move on to finer grits/polish until you are sure you've gotten out all the scratches from the previous one. Keep your work space clean. Avoid cross contamination. This is all sort of assuming you know the basic process.
    Anything specific you were looking for?
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  5. #4  
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    pretty much that - there's a number of guides online. I was just wondering about any tricks or other tips...

    thanx guys
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  6. #5  
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    Quote Originally Posted by C_Sensei
    pretty much that - there's a number of guides online. I was just wondering about any tricks or other tips...
    There are literally thousands of tricks and tips to building anything. What exactly are you looking for? Woodwork? Metalwork? ABS? Teflon? Math? Optics? Tools? Jigs?

    There is so much that goes into the building of a telescope, one can't just generalize.

    Can you at least provide a link or something else that points to the design of your scope, that would be a good starting point?
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  7. #6  
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    http://www.iceinspace.com.au/63-324-0-0-1-0.html

    ...perhaps.

    or maybe I should start with something simpler?
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  8. #7  
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    Quote Originally Posted by C_Sensei
    http://www.iceinspace.com.au/63-324-0-0-1-0.html

    ...perhaps.

    or maybe I should start with something simpler?
    It would depend on your skills to build. You may have noticed in your link the referral to Kriege book on building an Obsession. You will most likely need that book if you're going to build something as complicated as that truss dob. I've used it extensively to build my scopes as it has all the necessary principles for building them.

    Have you a proper workshop and tools for such a build?
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  9. #8  
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    The very first thing you need to procure is the primary mirror. A few things to consider:

    1) Your wallet. For example, I usually buy hand ground mirrors from Swayze or if I can get them, from Zambuto. However, there are other companies that put out quality mirrors; Galaxy, Pegasus and OMI to name a few. Nonetheless, you'll be shelling out the majority of your cash for one of these. One thing to remember is that if you get a mirror bigger than 15" or 18" (depending on the f-ratio) you'll be looking through the focuser standing on a ladder.

    2) Viewing. If you want a "fast" mirror (f-ratio 4-5) you'll be using it primarily for deep sky viewing as "slower" mirrors (f-ratio 8-10) are better suited for planetary viewing.

    3) Storage and usage. Can you store a big scope? Do you have the environment to use a big scope?

    4) Aperture is king!
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  10. #9  
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    yep aperture is KING indeed. I've got a store-bought 4" already, and I LOVE the deep sky - nothing much happening in the solar system anyway! And that includes the sun => $20 for a pair of homemade filters and there isn't much to see aside from sunspots.

    I was thinking something in the range of 12" to up to 16"...

    any ideas on mirror prices, or is it cheaper to grind your own; - also was wondering about the mount - I have come across plans for a plywood base that is stable and rotates easily.
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  11. #10  
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    Homemade solar filters? Please tell me you're joking.
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  12. #11  
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    No, I'm not joking.

    Follow the directions, obtain your filter material at a reputable telescope store, and you will get good results. I have already observed sun a number of times with it.
    I saw no sunspots in two observations in June, but a few were in the lower part in July.
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  13. #12  
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    Oh, that makes more sense. I thought you were making your own filter material somehow. I forgot about that foil that you can buy. The sun's spot cycle is in a lull right now, it should pick back up in a couple years. Once it does I'll probably get a filter for my scope too.

    Anyways, back to newtonians. It would be cheaper to grind your own but something in the size your looking to do would be a lot to tackle for a first time. Not to say it can't be done, but it would probably save you a lot of frustration to do a 6" first and then step it up.

    For 12-16" it would also be good to go with a quartz mirror instead of pyrex. They are a lot thinner and cool down quickly. 16" of pyrex, even with fans on it, is going to have to sit outside for hours before you get a good image.
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  14. #13  
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    Ah so ka!

    I didn't know that difference in properties! It pays to ask!

    I was thinking that 8" is only double what I'm using now, and 12" would probably be what I'd like to get hold of.
    The next question is what amount of concavity do I want to grind / buy for a better view of deep sky objects?


    I was dicking around with maybe using the lense mounting on my 4"; but the quality might not be all that great - here it is:
    http://www.harrisontelescopes.co.uk/...Telescope.html

    So I guess I'm also wondering about the quality of the supplied lenses that come with it. I understand you can get lenses costing 3 times the price of this telescope. Is there really that much difference in quality?

    I've already gazed upon M31, M81 M82 and M51 ( I think ) - they're maddeningly indistinct! The magnitude of what I'm looking at (as well as when I'm looking at) knocks me for a loop - but it's like getting a sudden kiss on the edge of your lip from a chick you desperately want to have sex with. IT'S NOT NEARLY ENOUGH!
    And pix in a book or online isn't quite the same thing...
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