16 inch ultra light weight telescope - version 3.0

[Chanlunlun]

Dear ATMers,

The version 3.0 of the ultra light scope is released. Instead of pure carbon fiber the struss is a hybrid of wood and carbon fiber tubes. In this way an extra of 1.0 kg is added to the total weight of the telescope.

Carbon fiber tubes are thin and light but have serious vibration. Though not seriously, the stability of the telescope still suffers. Hybridization with wooden struss greatly increases the stability. Wood is a good damper of vibration.

The price to pay for is the addition of 1 kg of total weight. Wood is light weight, but not as light as carbon fiber.

In addition the single arm diagonal holder was also replaced by a standard 3 legs spider. The three legs spider has less weight thus helps to compensate a little bit the increasing weight of the wooden struss. Now I have three options to choose from :-

1. Single pole design – total weight 14.7 kg, light weight but not very stable.
2. Carbon struss design – lightest weight 14.6 kg, reasonably stable but carbon tubes vibrates at high frequency.
3. Carbon – wood hybridization – heaviest at 15.6 kg, but stable.

I opt for design 3.

Best regards
Chan Yuk Lun
6 July 2015

[Water]

動畫 "復仇者聯盟" 中的 Tony Stark 可把 Iron Man 製作多個改良版本，現實中鏡神 Chanlunlun 兄同樣可把一支牛反望遠鏡製作多個改良版本，真的不可思議。

[PTS]

I found some carbon fibre tube at Ying Kee (Ap Liu Street).
They are about 2 cm in diameter, and about 35 cm long, with threaded ends. each will cost $150.

pts

[Chanlunlun]

I found some carbon fibre tube at Ying Kee (Ap Liu Street).
They are about 2 cm in diameter, and about 35 cm long, with threaded ends. each will cost $150.

pts

Thanks for your information.

However I need a total length of 6000 mm of carbon fiber. That will cost too much for me.

[BossKwan]

Dear Chan Sir,

I have no any experience of using carbon fiber meterials, I just know somtimes in some forms, carbon fiber can be harder than metal. As seen on your photos, these 6 mm carbon fiber tubes coupled with few sections and extend to about 5-6 feets, in such a lenght.... and looks so slim... I have a doubt and interested to know, is there really no serious vibration affecting practical observing?

By the way, how about using thicker sizes? 8mm or 10mm, are they available on the market? very expensive? Do you have these information? I love to know...
Thank you!

Peter Kwan

[Chanlunlun]

Dear Chan Sir,

I have no any experience of using carbon fiber meterials, I just know somtimes in some forms, carbon fiber can be harder than metal. As seen on your photos, these 6 mm carbon fiber tubes coupled with few sections and extend to about 5-6 feets, in such a lenght.... and looks so slim... I have a doubt and interested to know, is there really no serious vibration affecting practical observing?

By the way, how about using thicker sizes? 8mm or 10mm, are they available on the market? very expensive? Do you have these information? I love to know...
Thank you!

Peter Kwan

Hi Boss Kwan, long time no see.

Carbon fiber is no doubt very strong and light. However using thicker size such as 20 mm the weight will be no less than using wood. 20 mm diameter carbon fiber tubes are very expensive, considering the quantity that I am using.

When in a length of 1500 mm I am using, thin carbon fiber tubes tend to resonant easily at high frequency. The damping of carbon fiber is poor, at least no as good as wood. That's why I hybridizing carbon fiber with wood. However star test showed that such resonance seemed not affecting observation that much.

Now the vibrating problem is solved. Although a low tech stuff, wood seems to be the best overall material for construction.

[大黃傻貓GARFIELD]

Dear Chan Sir,

I have no any experience of using carbon fiber meterials, I just know somtimes in some forms, carbon fiber can be harder than metal. As seen on your photos, these 6 mm carbon fiber tubes coupled with few sections and extend to about 5-6 feets, in such a lenght.... and looks so slim... I have a doubt and interested to know, is there really no serious vibration affecting practical observing?

By the way, how about using thicker sizes? 8mm or 10mm, are they available on the market? very expensive? Do you have these information? I love to know...
Thank you!

Peter Kwan

Hi Boss Kwan, long time no see.

Carbon fiber is no doubt very strong and light. However using thicker size such as 20 mm the weight will be no less than using wood. 20 mm diameter carbon fiber tubes are very expensive, considering the quantity that I am using.

When in a length of 1500 mm I am using, thin carbon fiber tubes tend to resonant easily at high frequency. The damping of carbon fiber is poor, at least no as good as wood. That's why I hybridizing carbon fiber with wood. However star test showed that such resonance seemed not affecting observation that much.

Now the vibrating problem is solved. Although a low tech stuff, wood seems to be the best overall material for construction.

Wood is not actually "low tech" - we still cannot make such light and durable materials cheaply!

[BossKwan]

Hi Boss Kwan, long time no see.

Carbon fiber is no doubt very strong and light. However using thicker size such as 20 mm the weight will be no less than using wood. 20 mm diameter carbon fiber tubes are very expensive, considering the quantity that I am using.

Now the vibrating problem is solved..........

Right! long time no see...

Please don't mind my ignorance about carbon fiber. I have a few questions?

Can they be easily shortened by hand-saw?

Can they be easily drilled for small holes?

You are using those 6mm size, how long its original lenght each for shipping? Can you disclose the price?

[Chanlunlun]

Hi Boss Kwan, long time no see.

Carbon fiber is no doubt very strong and light. However using thicker size such as 20 mm the weight will be no less than using wood. 20 mm diameter carbon fiber tubes are very expensive, considering the quantity that I am using.

Now the vibrating problem is solved..........

Right! long time no see...

Please don't mind my ignorance about carbon fiber. I have a few questions?

Can they be easily shortened by hand-saw?

Can they be easily drilled for small holes?

You are using those 6mm size, how long its original lenght each for shipping? Can you disclose the price?

Hi BossKwan, your wish is my command.

Carbon fiber is very easy to cut by handsaw. They are as easy going as plywood.

Similarly they are very easy to drill. I haven't try them on lathe or milling machine, but I guess they are readily to be machined same as bronze or aluminium.

Each carbon fiber tube came with a standard length of 1000 mm ( 1 m). For a 6mm with 3 mm hole each piece cost around HK$ 23, including transportation fee. I bought them from TaoBao.

[BossKwan]

Please don't mind my ignorance about carbon fiber. I have a few questions?

Can they be easily shortened by hand-saw?

Can they be easily drilled for small holes?

You are using those 6mm size, how long its original lenght each for shipping? Can you disclose the price?

Hi BossKwan, your wish is my command.

Carbon fiber is very easy to cut by handsaw. They are as easy going as plywood.

Similarly they are very easy to drill. I haven't try them on lathe or milling machine, but I guess they are readily to be machined same as bronze or aluminium.

Each carbon fiber tube came with a standard length of 1000 mm ( 1 m). For a 6mm with 3 mm hole each piece cost around HK$ 23, including transportation fee. I bought them from TaoBao.

Many thanks for all of your answers!

As your description, carbon fiber is easy processing materials as aluminium. My original plan choses aluminium tube for the truss structure, this moment, there should be no any hesitation for me to take carbon fiber instead of aluminium.

Also thanks for your reminder, I today tried research on taobao for other sizes, truly, there are lots of different sizes, and of course including my desirable size: 10mm. Besides, most of the prices seem reasonable. That is really a good news for me...