鋁筒或碳纖筒

夸克星 註冊時間: 2004-12-13 文章: 6008 來自: NT

其實我見過jj12667枝10" F5牛頓鏡，用玻璃纖維做鏡筒，其實都已經好輕好硬。

白矮星 註冊時間: 2004-10-01 文章: 649

anguslau 寫到:

I remember a while ago (last year?) someone posted a source (in mainland china) of carbon fibre tubes here. Not sure if all carbon fibre tubes are suitable for telescope making...

I am also thinking about making a 10/12" astrograph myself. Though I am a novice in this area. If there are sufficient interest, I wonder if experienced people such as Subaru, Wah, Wong sir etc etc can help out in forming a small group for such an exercise?

My initial thoughts are:
1) 300mm f/3.8 parabolic mirror; purchased if possible, but can grind if necessary and there are someone who can guide me Embarassed

2) carbon fibre tube for reduced weight and less sensitivity to temp changes
3) 3/4" focuser, motorised; rigid enough for astro imaging
4) using Philipp Keller 3" corrector (0.95x) gives 50mm corrected field (-> 300mm f/3.6 f.l.=1083mm); accommodates upto 16803 or similar sensor
5) using Philipp Keller 3" reducer (0.73x) gives 28mm corrected field (-> 300mm f/2.8 f.l.=832mm); accommodates upto APS-C sensors
6) weight <14kg; can be carried by EM-200; is this possible??

Good project, a reseach level!
In your plan, I feel interested in the Philipp Keller's reducer corrector and just have briefly viewed some of its information, it looks an excellent corrector with professional grade which can be used with any sizes of big reflecting scopes. Hope this is your good choice. I also agreed to Subaru's suggestions, let your giant be loaded on a more heavy duty mount, like Paramount, Perfect! Or at lease an Astro-Physic mount. Let me guess further, are you going to have a fixed site for this planning gears....... Smile

As a HK amateur and because of the structure of our city, most of us are always facing a confusion of this: the investment on buying a big reflector or DIY one may not cost you too much, but how to have a good and fixed location for you gears is really a problem, not like other countries, say US or Canada, most people are able to enjoy their backyard astronomy or even easily built up their private observatory. Although some of our local amateurs can put their gears on mobile, traveling to better site, that also limit the size of our gears. How can we enjoy the bigger? ........the only thing can help is still the MONEY...... the more, the better solution......to make your dream of having a house with roof or a remote site with less-light pollution to come true....... Laughing

白矮星 註冊時間: 2004-10-01 文章: 649

anguslau 寫到:

This was the previous thread on carbon fibre tube. You probably remember as you were in those discussions...
http://www.hkastroforum.net/viewtopic.php?t=8945&postdays=0&postorder=asc&start=0

Thanks anguslau for your digging out this old thread, however I have asked JJ about this but he told me that the guy long time ago had stopped this business or refused any personal orders.... Sad

紅巨星 註冊時間: 2005-04-15 文章: 595

BossKwan 寫到:

Good project, a reseach level!
In your plan, I feel interested in the Philipp Keller's reducer corrector and just have briefly viewed some of its information, it looks an excellent corrector with professional grade which can be used with any sizes of big reflecting scopes. Hope this is your good choice. I also agreed to Subaru's suggestions, let your giant be loaded on a more heavy duty mount, like Paramount, Perfect! Or at lease an Astro-Physic mount. Let me guess further, are you going to have a fixed site for this planning gears....... Smile

As a HK amateur and because of the structure of our city, most of us are always facing a confusion of this: the investment on buying a big reflector or DIY one may not cost you too much, but how to have a good and fixed location for you gears is really a problem, not like other countries, say US or Canada, most people are able to enjoy their backyard astronomy or even easily built up their private observatory. Although some of our local amateurs can put their gears on mobile, traveling to better site, that also limit the size of our gears. How can we enjoy the bigger? ........the only thing can help is still the MONEY...... the more, the better solution......to make your dream of having a house with roof or a remote site with less-light pollution to come true....... Laughing

I actually have two lines of thoughts. One is to make the biggest possible astrograph to fit into my tiny rooftop observatory, and most preferably without the need to upgrade my current mount. The main usage will be for narrowband imaging at very fast focal ratios (~f/4 - f2.8 ). The above spec is essentially identical to the ASA 12" astrograph. I just found their pricing way too high... Thinking more about it, a 10" may be more realistic for the EM200.

The second line of thought is to build the largest portable astrograph which I can carry with me for overseas trips. I believe an 8" or 7" may be possible. For travelling use, the criteria will be even more stringent. I would like it to be extremely light so that it can be carried by a EM11. So the OTA itself must not be >6kg. Secondly, I very much prefer to carry the optical parts as hand-carry luggage for a number of reasons. The scope should have at least an APS-C field circle and can operate ~f/4-f/2.8. I am not sure such a scope exist commercially. But it will be an utlimate travelling astrograph if it can be made... Rolling Eyes

紅巨星 註冊時間: 2005-04-15 文章: 595

BossKwan 寫到:

... however I have asked JJ about this but he told me that the guy long time ago had stopped this business or refused any personal orders.... Sad

Its a pity. I hope we can locate another source in the mainland. Or perhaps the one in Taiwan is still in business.

anguslau 寫到:

BossKwan 寫到:

... however I have asked JJ about this but he told me that the guy long time ago had stopped this business or refused any personal orders.... Sad

Its a pity. I hope we can locate another source in the mainland. Or perhaps the one in Taiwan is still in business.

A garage owner suggested the name, according to the information, the factory makes carbon fibre car parts according to specifications/drawing by customers.

However, I have never deal with them or have any idea whether they do astronomical optical tubes.

I got the information using the name on the web:

http://flinkcarbon.cn.alibaba.com/

Maybe funoooo, Eddy or S Y Yuen can check it for us as it is in the same region where they work.

中子星 註冊時間: 2007-07-06 文章: 1803

I can give you guys some advise on aluminum but not carbon fibre. I think you can still find with some efforts 4 to 6 inches seamless aluminum tubes in the retail market. With the diameter you are talking about, it must be tailor made by factory. Now, it all comes down to money. Aluminum factory having extrusion machines and die making is able to do it for you. A die is needed to produce the shape and diameter you want and you need to pay for that. If you produce only a couple of tubes, the cost does not justify by itself. The more tubes produce, the lower the cost it will be. For a harder material, you can select a harder aluminum wrought alloy with a T 6 heat treatment grade. The wall can be as thin as possible to reduce the weight. Surface can be subsequently powder coat by polyester resin to achieve a glossy hard surface. As aluminum is more ductile than carbon fiber, it is easier for post treatment processing. This maybe the reason that you do not find a carbon fibre tube in large diameter commerically. So, my dear friends, money talks here. Very Happy

Let me know if you are still interest, I can give you a hand on this project 鬼點子

白矮星 註冊時間: 2004-10-01 文章: 649

鄧登凳寫到:

A garage owner suggested the name, according to the information, the factory makes carbon fibre car parts according to specifications/drawing by customers.

However, I have never deal with them or have any idea whether they do astronomical optical tubes.

I got the information using the name on the web:

http://flinkcarbon.cn.alibaba.com/

Maybe funoooo, Eddy or S Y Yuen can check it for us as it is in the same region where they work.

That's good! A good source maybe helpful. Smile

白矮星 註冊時間: 2004-10-01 文章: 649

anguslau 寫到:

I actually have two lines of thoughts. One is to make the biggest possible astrograph to fit into my tiny rooftop observatory, and most preferably without the need to upgrade my current mount. The main usage will be for narrowband imaging at very fast focal ratios (~f/4 - f2.8 ). The above spec is essentially identical to the ASA 12" astrograph. I just found their pricing way too high... Thinking more about it, a 10" may be more realistic for the EM200.

The second line of thought is to build the largest portable astrograph which I can carry with me for overseas trips. I believe an 8" or 7" may be possible. For travelling use, the criteria will be even more stringent. I would like it to be extremely light so that it can be carried by a EM11. So the OTA itself must not be >6kg. Secondly, I very much prefer to carry the optical parts as hand-carry luggage for a number of reasons. The scope should have at least an APS-C field circle and can operate ~f/4-f/2.8. I am not sure such a scope exist commercially. But it will be an utlimate travelling astrograph if it can be made... Rolling Eyes

Yes, your idea for a 10" astrograph is more practical and your EM-200 has enough loading for it besides.

Your second idea is also good, a more portable astrograph for overseas trips can offer you more chances to collect the images..... Smile

夸克星 註冊時間: 2003-07-02 文章: 5234

XR250 寫到:

其實我見過jj12667枝10" F5牛頓鏡，用玻璃纖維做鏡筒，其實都已經好輕好硬。

感有無門路整到?

夸克星 註冊時間: 2003-07-02 文章: 5234

syyuen168 寫到:

I can give you guys some advise on aluminum but not carbon fibre. I think you can still find with some efforts 4 to 6 inches seamless aluminum tubes in the retail market. With the diameter you are talking about, it must be tailor made by factory. Now, it all comes down to money. Aluminum factory having extrusion machines and die making is able to do it for you. A die is needed to produce the shape and diameter you want and you need to pay for that. If you produce only a couple of tubes, the cost does not justify by itself. The more tubes produce, the lower the cost it will be. For a harder material, you can select a harder aluminum wrought alloy with a T 6 heat treatment grade. The wall can be as thin as possible to reduce the weight. Surface can be subsequently powder coat by polyester resin to achieve a glossy hard surface. As aluminum is more ductile than carbon fiber, it is easier for post treatment processing. This maybe the reason that you do not find a carbon fibre tube in large diameter commerically. So, my dear friends, money talks here. Very Happy

Let me know if you are still interest, I can give you a hand on this project 鬼點子

Some years ago, I made my telescopes with Zinc-Iron roll tubes, and I was quite envy the telescopes with Aluminium tubes. I know it is difficult to solder Aluminium, and that's why it is difficult to make the tube.

Since there are now quite a lot of OTAs made in China or Taiwan, I am interested to see if we can source some kits (tubes, tube ring, tube end enforcement rings, etc...) from let's say Maxvision, Synta, GSO, Skywatcher, etc... and put the high end focuser, mirror cells, and mirrors, etc... to fabricate our own design.

The tubes made by these brands are quite good and not so heavy.

Subaru 寫到:

XR250 寫到:

其實我見過jj12667枝10" F5牛頓鏡，用玻璃纖維做鏡筒，其實都已經好輕好硬。

感有無門路整到?

國內有很多玻璃纖維廠，我老闆亦有一間玻璃纖維廠（生產火車車廂內的門柱、牆壁、天花、電視架、…），不過可以告訴你，其價錢絕對比用鋼做還貴，加上其模具費亦因尺寸大亦變得相當高，如果你不介意價錢貴的話，可以試試PM我。
此外我亦有朋友有碳纖供應商（深圳）在為他生產面板，據他所講如果要做大鏡筒的話，這類工廠未必願意做，除訂單類多少的問題外，還有是材料訂購並不容易，如果你有需要的問，我亦可找朋友要那個碳纖維廠的資料給你。

紅巨星 註冊時間: 2005-04-15 文章: 595

If money is not a major concern, Dream Telescopes have some very interesting carbon OTAs:
http://www.dreamscopes.com/pages/tubes-honeycomb.htm

Their tubes are very thick (but light) since they are sandwich cored. But they claim extremely high performance compared to conventional carbon tubes. They also produce custom tubes (such as round tubes with flat top & bottom) and other accessories (mirror cells etc) and have carbon truss tubes for sale. Quite interesting...

I wish they (or someone else) produce carbon fibre scope cases and luggage suit cases as well. It will save quite a few kgs for air travel while providing excellent protection. My old Samsonite suit case is quite light but very very strong, it is fabricated using ABS plastics. But can longer find these anymore since all hard cases nowadays uses cheap PP plastics. Its a pity...

原恆星 註冊時間: 2003-08-06 文章: 87 來自: Kowloon

Check this site for CF tubes (up to 8") and please also check your wallet:

http://www.carbon-tube.com/round.php

中子星 註冊時間: 2007-07-06 文章: 1803

Everybody wants light wegit but back off by the price. So, again moeny talk here Mr. Green

Tan14 寫到:

Check this site for CF tubes (up to 8") and please also check your wallet:

http://www.carbon-tube.com/round.php