How to building an aluminium skeleton for Dobsonian

[david_kmng]

Dear all,

I would like to build a truss structure for a Dobsonian mirror box with alumimium. I want to do some proof-of-concept first. Basically, it will be two rectangular frames, using rectangular aluminium tubes. These two frames will be joint by other Al. tubes to form triangles.

Can anyone tell me where can I find shops to build the frame? What do you think if I look for shops building Al. window frames? How much it will probably cost?

Thanks in advanced.

[mbike]

David:

What is the size that you plan to build? I am also planning to build a 8" dobsonian, I have bought 2 square aluminum tubesfrom 　. The price of a 0.5" size (per foot) is HK$2. You can go to some local 五金鋪 and ask the price of a 1" size aluminum tube, I guess it may be $4 per foot. But how can you connect it? What is your plan of secondary mirror holder? May be we can build together.

Regards,
mbike

[XR250]

Try this one, although it is not a newtonian telescope.
10" reflector on a small equatorial mount.
http://www.trivalleystargazers.org/gert ... rc_10.html

[david_kmng]

Thanks mbike and XR250.

Hi mbike, I have sent you my phone number in pm. Please feel free to call me at any time. I am so eager to build my scope and share with someone my design.

XR250, thanks for the URL. The scope is very much like what I have in my mind: simple truss tube. I want to build a alt-alz dobsonian first.

[Subaru]

我建議不如在農莊攪個杜蘇氏式望遠鏡製作分享會, 由d高手分享他們的心得, 不知大家意下如何? 又有多少人希望參加?

[bandofbrother]

好提議...
如果有，我會去參加

[david_kmng]

When?

Anyway, I think I will start doing a simple framework later this week. I was too busy last week (many overnight work .. )

Regards,
David

[01307699d]

我都想知道點樣整杜蘇鏡
唔知幾時有呢???

[HK.Raymond.Tse]

Pls go ahead to arrange a Dob workshop. I shall attend.

My next target will be a 20-inch ATM (trust structure only, mirror to be purchased) Dob !

[Chanlunlun]

Pls go ahead to arrange a Dob workshop. I shall attend.

My next target will be a 20-inch ATM (trust structure only, mirror to be purchased) Dob !

Dear Mr. Raymond,

Comercially available 20 inch mirrors mainly have f/ratio of 5 which means that the zenith eyepiece height is too far high above ground level rendering the telescope to be of limited practical value in Hong Kong. Furthermore the mirror normally has a trhickness of 2 inches, weighing 50 lbs, glass alone !! Your finished Dob will easily reach a weight of exceeding 120 lbs.

The best focal ratio is f/3.5, but not available commercially, however.

Best regards
Chan Yuk Lun

[HK.Raymond.Tse]

How about purchasing 20-inch F4 mirror (Strehl ratio 0.96) from Chan Sir ?

[Subaru]

How about purchasing 20-inch F4 mirror (Strehl ratio 0.96) from Chan Sir ?

鏡神's art is priceless.