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Carbon fiber truss tubes advice help

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#1 javad

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Posted 21 October 2021 - 03:21 AM

Hello, 

 

Can I replace 16 mm OD 1mm wall thickness 6063 aluminium truss tubes with the same dimensions CF tubes? Even, could I go down in size to reduce cost/weight?

 

Also, what sources do you recommend for such tubes? I need 6 pc 1000mm ones, at many shops the lengths are not evenly dividable by 1000mm, for ex, 60 inches which is 1500mm, in this case i will be left with 6  500 mm leftovers, waste of money. Many other lengths also don't work.



#2 Oberon

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Posted 21 October 2021 - 04:38 AM

eBay is your friend, and you can certainly do the same size.



#3 calypsob

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Posted 21 October 2021 - 05:00 AM

Ebay for the cheapstuff dragon plate for good stuff.

A local supplier is 20% cheaper if you buy full length pieces which are typically 48 to 96”

and you can rule out freight


Edited by calypsob, 21 October 2021 - 05:00 AM.

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#4 Pinbout

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Posted 21 October 2021 - 08:26 PM

Hello, 

 

Can I replace 16 mm OD 1mm wall thickness 6063 aluminium truss tubes with the same dimensions CF tubes? Even, could I go down in size to reduce cost/weight?

 

Also, what sources do you recommend for such tubes? I need 6 pc 1000mm ones, at many shops the lengths are not evenly dividable by 1000mm, for ex, 60 inches which is 1500mm, in this case i will be left with 6  500 mm leftovers, waste of money. Many other lengths also don't work.

How’s your supply chain over there during these Covid days? 


Edited by Pinbout, 21 October 2021 - 08:26 PM.


#5 Bob4BVM

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Posted 21 October 2021 - 08:58 PM

Hello, 

 

Can I replace 16 mm OD 1mm wall thickness 6063 aluminium truss tubes with the same dimensions CF tubes? Even, could I go down in size to reduce cost/weight?

 

Also, what sources do you recommend for such tubes? I need 6 pc 1000mm ones, at many shops the lengths are not evenly dividable by 1000mm, for ex, 60 inches which is 1500mm, in this case i will be left with 6  500 mm leftovers, waste of money. Many other lengths also don't work.

Just how much weight are you saving with CF ?

1mm wall Al tube is already pretty light and alot of the weight is far from the UTA.

 

Of course is you want CF just for the looks, that's another story but it would not be my choice due to  some of the undesirable properties of CF.  Worst of those being it's pretty fragile to being crushed or even nicked weakens it.  Al tube can take a beating and even with a few dents will still be structurally sound. If a CF tube gets bumped or pinched with a hard object it does not dent, it fractures, as in crushed., and it's over for the tube.  For a transportable scope that is always a possibility so you have to be very careful the protect the CF tubes from impact.

CS

Bob


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#6 javad

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Posted 21 October 2021 - 10:17 PM

Just how much weight are you saving with CF ?
1mm wall Al tube is already pretty light and alot of the weight is far from the UTA.

Of course is you want CF just for the looks, that's another story but it would not be my choice due to some of the undesirable properties of CF. Worst of those being it's pretty fragile to being crushed or even nicked weakens it. Al tube can take a beating and even with a few dents will still be structurally sound. If a CF tube gets bumped or pinched with a hard object it does not dent, it fractures, as in crushed., and it's over for the tube. For a transportable scope that is always a possibility so you have to be very careful the protect the CF tubes from impact.
CS
Bob

I have an ambitious plan to build the lightest 10" f/5 dob in the known universe. I will save 200-300 grams by switching to CF. 6 m aluminium piping is 0.97 kg, A 1 m CF tube is around 100g.
As a baxkground. I use a hexapod design and will be using plastic heim joints, aluminium screws, titanium bolts and so on to save as much weight as possible. My primary mirror is 3.7 kg and I am aiming for 5-6 kg for the whole OTA.

Edited by javad, 21 October 2021 - 10:20 PM.

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#7 javad

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Posted 21 October 2021 - 10:24 PM

How’s your supply chain over there during these Covid days?



God it is awful as ever! In azerbaijan, I basically have to import everything. I use freight forwarders and some suppliers refuse to ship to freight forwarders, like mcmaster. then i have to jump around switching my forwarder to see which one is not blacklisted. delivery times are very long, lengthy customs processes, bla bla. I got
lucky and ordered a mirror secondary pair from Agena right before the pandemic.

I am looking to buy some orion optics stuff, but dont know how to import, because almost no freight forwarders ship from the EU.

#8 javad

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Posted 21 October 2021 - 10:25 PM

eBay is your friend, and you can certainly do the same size.


I am kinda worries about the quality of ebay stuff. A lot of chinese sellers with poorly translated descriptions.

#9 javad

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Posted 21 October 2021 - 10:30 PM

Ebay for the cheapstuff dragon plate for good stuff.
A local supplier is 20% cheaper if you buy full length pieces which are typically 48 to 96”
and you can rule out freight



I have considered dragon, but they dont do 39" inches, or 3ft, with 48" ill waste 6x9" tube pieces , considering dragon is very expensive. I found a netherlands suppliers with all the metric sizes, but dont know how to have them shipped here.

#10 Oberon

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Posted 22 October 2021 - 05:20 AM

I am kinda worries about the quality of ebay stuff. A lot of chinese sellers with poorly translated descriptions.

I’ve only bought 500mm lengths of 94mm and 100mm CF tube on ebay from Chinese sellers but the quality was excellent.



#11 calypsob

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Posted 22 October 2021 - 09:12 AM

I have considered dragon, but they dont do 39" inches, or 3ft, with 48" ill waste 6x9" tube pieces , considering dragon is very expensive. I found a netherlands suppliers with all the metric sizes, but dont know how to have them shipped here.

Have you considered making it yourself?



#12 javad

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Posted 22 October 2021 - 10:49 PM

Have you considered making it yourself?



Haha, maybe one day, when I have a proper workshop. It is well beyond my means right now.

#13 Benach

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Posted 23 October 2021 - 03:15 AM

I have considered dragon, but they dont do 39" inches, or 3ft, with 48" ill waste 6x9" tube pieces , considering dragon is very expensive. I found a netherlands suppliers with all the metric sizes, but dont know how to have them shipped here.


Which suppliers are you referring to?

#14 javad

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Posted 23 October 2021 - 03:34 AM

Which suppliers are you referring to?


https://www.carbonwe...w=WebShopBasket
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#15 Benach

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Posted 24 October 2021 - 05:53 PM

https://www.carbonwe...w=WebShopBasket


If you want, I think I can order it online for you and send it to you via mail. Being Dutch, this should be no big issue for me. PM me for details please.
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#16 careysub

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Posted 14 November 2021 - 12:55 PM

If you want to build the lightest possible truss tube Dob as your actual objective, then go for it.

 

But, as a carbon fiber fan, I think this is one of the least compelling uses of carbon fiber in a telescope. I would only use aluminum tubes myself, they are less prone to damage.


Edited by careysub, 15 November 2021 - 09:39 AM.

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#17 javad

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Posted 15 November 2021 - 01:11 AM

Thank you everybody, thanks to your advice, I think I'll stick with aluminium tubes.


Edited by javad, 15 November 2021 - 01:12 AM.


#18 javad

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Posted 15 November 2021 - 01:11 AM

If you want, I think I can order it online for you and send it to you via mail. Being Dutch, this should be no big issue for me. PM me for details please.

Thank you Beach, for such kind offer, great to have such a great community here!



#19 dan_h

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Posted 15 November 2021 - 09:36 AM

Just how much weight are you saving with CF ?

1mm wall Al tube is already pretty light and alot of the weight is far from the UTA.

 

Of course is you want CF just for the looks, that's another story but it would not be my choice due to  some of the undesirable properties of CF.  Worst of those being it's pretty fragile to being crushed or even nicked weakens it.  Al tube can take a beating and even with a few dents will still be structurally sound. If a CF tube gets bumped or pinched with a hard object it does not dent, it fractures, as in crushed., and it's over for the tube.  For a transportable scope that is always a possibility so you have to be very careful the protect the CF tubes from impact.

CS

Bob

There must be different grades of CF tubing.  I raced kayaks for a decade and everyone in the sport used CF paddles.  A shaft for a double bladed kayak paddle was typically cut from a 1" diameter, 48" length of hollow CF tube.  I have seen a number of paddle blades fail under load but never heard of a shaft failing.   And yeah, the paddles took a beating during a race. The only time they were babied was when they were packed for airline travel. 

 

I can't imagine truss tubes being abused anywhere near the level  that our paddles received. 

 

dan


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#20 careysub

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Posted 15 November 2021 - 10:03 AM


 

There must be different grades of CF tubing.  I raced kayaks for a decade and everyone in the sport used CF paddles.  A shaft for a double bladed kayak paddle was typically cut from a 1" diameter, 48" length of hollow CF tube.  I have seen a number of paddle blades fail under load but never heard of a shaft failing.   And yeah, the paddles took a beating during a race. The only time they were babied was when they were packed for airline travel. 

 

I can't imagine truss tubes being abused anywhere near the level  that our paddles received. 

 

dan

I think they are different. Looking at this:

https://fishingtopic...r-kayak-paddle/

I am reading about ABS resin, and ABS injected nylon with the carbon fiber. Seems like it is using a tough polymer body with CF stiffening rather than CF maximizing layups with a minimum amount of epoxy.

 

Part of what I was referring to in my brief post was that people pay a lot of money for CF tubes for basically cosmetic reasons that are vulnerable to nicking, and that in a true truss many of the reasons for using CF are reduced due the stiffness being mostly provided by the truss structure, and you get the most benefit in a truss with a larger diameter tube which get very expensive in CF, and people tend to go with thin tube walls which become vulnerable to accidental impact.


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#21 Kunama

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Posted 15 November 2021 - 02:44 PM

I used paddle shafts for my truss tubes to save weight as well as their aesthetics…. Whilst my aim was never to build a lightweight, using carbon fibre and titanium along with other lightweight ideas, I managed to make a full UTA light enough to allow a low profile mirrorbox as well as keeping the altitude trunnions mounted very low…..

Attached Thumbnails

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Edited by Kunama, 15 November 2021 - 02:47 PM.

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#22 a__l

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Posted 15 November 2021 - 04:55 PM

Also, what sources do you recommend for such tubes? I need 6 pc 1000mm ones

Buy on AliExpress. A week ago I bought 15 CF tubes there, each 1000 mm long. Large selection of diameters.

 

Think about how you will fix them. Metric tubes are not compatible with American clamps. I have a lathe and will make inch size aluminum inserts without any problem.

 

My goal is less ambitious. I only want to operate my telescope with two hands instead of four. The means of achieving are about the same. Aluminum, titanium and carbon.


Edited by a__l, 15 November 2021 - 05:04 PM.


#23 a__l

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Posted 15 November 2021 - 05:11 PM

There is a nuance for UTA. You will not be able to make significantly less weight for 2" eyepieces, coma corrector, secondary, finder, focuser without loss of quality. Therefore, for a small telescope (12"), weight savings will be insignificant and you will not be able to greatly reduce the total weight telescope "tube".


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#24 careysub

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Posted 15 November 2021 - 05:42 PM

I used paddle shafts for my truss tubes to save weight as well as their aesthetics…. Whilst my aim was never to build a lightweight, using carbon fibre and titanium along with other lightweight ideas, I managed to make a full UTA light enough to allow a low profile mirrorbox as well as keeping the altitude trunnions mounted very low…..

Where do you source your paddle shafts from?



#25 careysub

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Posted 15 November 2021 - 09:52 PM

I have played around on spreadsheets with unusual CF truss tube implementations, like hand lay-ups of unidirectional CF around a poplar pole (low density wood, bamboo would be even lighter). You get the greatest stiffness with unidirectional fiber (which is cheap because it isn't woven) and the wood pole makes it crush proof (and provides the necessary lateral bonding). There are other similar sorts of possibilities. Some one should try it sometime (or point to someone who has).

 

But this is not what people usually mean when they talk about CF poles.


Edited by careysub, 16 November 2021 - 07:59 AM.



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