Hello all..
I have been thinking lately of making a carbon fibre tube, solid or truss style but finding the information with google seems rather hopeless. So does anyone have any links or where I could get some information on how to design and build a OTA with CF also where to buy the the tape ,epoxy etc to make it......
how do you go about fabricating it..do you have to vacuum bag it etc?, bake it?
I would love to have a go so all info on how you have done something with this would be greatly appreciated..
cheers Gary
For the 6" Gary? http://www.astroclassifieds.com/foru...330/index.html
I am about to receive some 8" optics, and will do the whole exercise again, this time I will document it better.
Try this to start with, and if you like give me a shout for more info. I will be away for 6 weeks though, so any time after 8th October
Gary
Thanks Gary for that link...
some great info there, I will have to register to get a look at those pics you posted..
going to build a 8' f4.5 newt next year and a CF tube would be nice and keep the weight down on my gm-8.
That would be great if you did a post on your next one!!!
your help would be very much appreciated in the future!!! ::
cheers
Hi guys,
It's been a while, but I used to build the carbon fibre landing gear doors for the Airbus A320 when i worked at Hawker De Havilland.
Not sure where you would get the material, but the procedure goes like this:
The material we would use is called "pre-preg", meaning the material is already impregnated with the resin. This material is layed out, layer by layer, onto a metal mandrel in the shape that you want. The layer that makes contact with the tool is the "smooth" side. The layers would be vaccuum compacted after every few layers.
Once all layers were applied, the final bag was prepared. This consisted of a layer of "peel ply", to prevent the rest of the bag sticking to the job. Then a layer of fibreglass material. This absorbs excess resin from the job. Then some layers of plastic, to stop the resin getting any further. Followed up with breather cloth, and the final thick plastic bag to seal the vaccuum.
This whole assembly is rolled into an autoclave, which is basicallly a very big pressurised oven. Its cooked for a few hours at high temperature and pressure.
There are different procedures for making seamless tubes, but I think they might go beyond the ability of the home user, as they are woven strands.
Hello,
i am in the process of finishing a carbon tube for my 222mm f5.9 and there are a few things i learned with this project:
- it is expensive to experiment with carbon fibre!
-it is also addictive; like silk, it has a special lustre.
-the first important thing is to have a solid form to wrap that precious fibres. I made mine from a 5mm cardboard tube i got for a piece of pie at the local "light-weight barrel factory", they made it up to my requirements for about 20$
-the carbon layers are 3x KDK-8042 and 1 layer KDL-8005
-pressure was applied by wrapping the epoxy-soaked carbon fabric with silicone treated polyester-tape, to remove excess resin.
-the finished tube (1355mm) is 1630g , 2mm thick and very solid.
The nine point mirror cell is 280g and carbon too.
I am putting in a curved,carbon tree vain spider and the focuser will be the only metal part exept for a few springs and bolts.
The aim is to have the OTA below 5kg, I hope...to finish it for the next new moon.
I love this kind of work and wonder what the next project will be!
clear skies!
Hello,
i am in the process of finishing a carbon tube for my 222mm f5.9 and there are a few things i learned with this project:
- it is expensive to experiment with carbon fibre!
-it is also addictive; like silk, it has a special lustre.
-the first important thing is to have a solid form to wrap that precious fibres. I made mine from a 5mm cardboard tube i got for a piece of pie at the local "light-weight barrel factory", they made it up to my requirements for about 20$
-the carbon layers are 3x KDK-8042 and 1 layer KDL-8005
-pressure was applied by wrapping the epoxy-soaked carbon fabric with silicone treated polyester-tape, to remove excess resin.
-the finished tube (1355mm) is 1630g , 2mm thick and very solid.
The nine point mirror cell is 280g and carbon too.
I am putting in a curved,carbon tree vain spider and the focuser will be the only metal part exept for a few springs and bolts.
The aim is to have the OTA below 5kg, I hope...to finish it for the next new moon.
I love this kind of work and wonder what the next project will be!
clear skies!
Hello Uyukon,
That tube looks a real beauty.
Can I ask how much would it have cost you all up for the tube?
How do you apply the silicone treated polyester tape. Is it just wrapped around the tube very tight till the epoxt sets..
Also how do you treat the former underneath to stop it sticking? and how do you remove it?
Thanks for any help..
cheers Gary
Can I ask how much would it have cost you all up for the tube?
How do you apply the silicone treated polyester tape. Is it just wrapped around the tube very tight till the epoxt sets..
Also how do you treat the former underneath to stop it sticking? and how do you remove it?
Thanks for any help..
cheers Gary
Hi Gary,
- carbon fibre is expensive! I spend close to 500 Euros on that stuff.
- the tape is wrapped overlapping and as thight as possible, the excess resin will flow out+ and makes a mess... You apply quite good pressure on the former by adding round to round.I mounted the former on a axis, a friend of mine was cranking and turning while i guided the tape. You need to finish that job in about 1 h, before the epoxy gets sticky.
-Epoxy will not stick to polyethylen plastic film, any old gardening plastic will do.( thin+new to prevent wrinkles)
- to remove the former I had to destroy it, but since it was cardboard paper that was not a big thing. It made a nice big fire.
Cutting+drilling carbon/epoxy will eat up a lot of tools.
Don't work in the sunshine, it gets too hot.
But I am quite happy with the results so far, just waiting for a clear night!
Have fun with that beautiful black stuff!
Hi Gerry,
I dug in my papers and found out that the carbon was rather 340 Euros ( material for the tube, mirror cell+spider+ some extra, just in case something would go wrong( and it did....). I got the stuff from http://www.carbon-vertrieb.com, in case you find a cheaper supplier, please let me know, i might even consider air mail shippment for such a lightweight material.
You could also consider to make the tube out of carbon rowings (monofilament fibre).Much cheaper!
I tried but failed because of a too weak former, it collapsed when wrapping, next time I do it better.
For the 260mm o.d.tube 2mm thickness is also not nessesary, 1-1.5 will do, saves you weight+costs.
Clear skies!
Hello Garyh,
I've actually just joined IceInSpace the other day, and I have 90% completed making some fibreglass components for a prototype telescope (sandwich core fibreglass sectioned tube, mirror cell, counterweight rings). I haven't worked on it for about a year, as I had postponed it to construct an observatory which is still in progress. It is my second fibreglass project, the first being a laundry chute I made a few years ago.
I have basically learnt it by myself with just web references and supplier info pamphlets for instruction - needless to say it has been a learning experience. However, I haven't tried carbon fibre yet - it costs a fortune and I want to perfect my skills first. I'm glad I did, as although the tube is turning out quite good, I will do it better next time! For one thing, I used too many layers of cloth and too much resin so it is heavier than it should be (but boy is it stiff and strong!!). I don't think there is much difference in technique, although I believe that carbon fibre has different wet-out characteristics to e-glass.
For fibreglass supplies, I use the following sources:
- ATL Composites in Queensland - very helpful staff !!!!!! They also supplied pamphlets on their products and some other info. (website: http://www.atlcomposites.com ) - I use them for most of my supplies - they have specialised laminating epoxy resins, carbon cloth, etc, etc.
- Fibreglass Material Services Pty Ltd, Unit 1/ 19 Boden Rd Seven Hills 2147(02) 9624 2811. They also have a lot of stuff, but not as much as ATL. However, can be more handy as you can drop in and buy over the counter.
- Advanced Composites in Unanderra - not very helpful staff, you've got to know precisely what you want and just order it. However, I believe the company has changed hands / merged / whatever and their website is no longer active, so you would have to chase it up. They were the only place I found that supplied Nomex Honeycomb which I needed,
although there is another company in WA that may have it (http://www.fibreglass-resin-sales.com.au/home.html).
I also have heaps of pictures (and a lot of practical advice) if you are interested.
Regards,
David
Hi Gerry,
I dug in my papers and found out that the carbon was rather 340 Euros ( material for the tube, mirror cell+spider+ some extra, just in case something would go wrong( and it did....). I got the stuff from http://www.carbon-vertrieb.com, in case you find a cheaper supplier, please let me know, i might even consider air mail shippment for such a lightweight material.
You could also consider to make the tube out of carbon rowings (monofilament fibre).Much cheaper!
I tried but failed because of a too weak former, it collapsed when wrapping, next time I do it better.
For the 260mm o.d.tube 2mm thickness is also not nessesary, 1-1.5 will do, saves you weight+costs.
Clear skies!
Thanks Uyukon for that info, I will have to chase up the prices over here to see if the cost will be prohibitive..hopefully they won`t be too expensive..
cheers Gary
Quote:
Originally Posted by David Fitz-Henr
Hello Garyh,
I've actually just joined IceInSpace the other day, and I have 90% completed making some fibreglass components for a prototype telescope (sandwich core fibreglass sectioned tube, mirror cell, counterweight rings). I haven't worked on it for about a year, as I had postponed it to construct an observatory which is still in progress. It is my second fibreglass project, the first being a laundry chute I made a few years ago.
I have basically learnt it by myself with just web references and supplier info pamphlets for instruction - needless to say it has been a learning experience. However, I haven't tried carbon fibre yet - it costs a fortune and I want to perfect my skills first. I'm glad I did, as although the tube is turning out quite good, I will do it better next time! For one thing, I used too many layers of cloth and too much resin so it is heavier than it should be (but boy is it stiff and strong!!). I don't think there is much difference in technique, although I believe that carbon fibre has different wet-out characteristics to e-glass.
For fibreglass supplies, I use the following sources:
- ATL Composites in Queensland - very helpful staff !!!!!! They also supplied pamphlets on their products and some other info. (website: http://www.atlcomposites.com ) - I use them for most of my supplies - they have specialised laminating epoxy resins, carbon cloth, etc, etc.
- Fibreglass Material Services Pty Ltd, Unit 1/ 19 Boden Rd Seven Hills 2147(02) 9624 2811. They also have a lot of stuff, but not as much as ATL. However, can be more handy as you can drop in and buy over the counter.
- Advanced Composites in Unanderra - not very helpful staff, you've got to know precisely what you want and just order it. However, I believe the company has changed hands / merged / whatever and their website is no longer active, so you would have to chase it up. They were the only place I found that supplied Nomex Honeycomb which I needed,
although there is another company in WA that may have it (http://www.fibreglass-resin-sales.com.au/home.html).
I also have heaps of pictures (and a lot of practical advice) if you are interested.
Regards,
David
thanks David... thats heaps of info for me to chew on..I shall check out the suppliers to see what they have and the costs..
Do you have any pics of how your tube is coming along..?
Thanks again for all that useful info..
cheers
Hello Gary,
Here are some pics of my tube and construction of a light trap. It is constructed from 3 layers of e-glass inside 6mm Nomex honeycomb with another 3 layers of e-glass on the outside (next time I will just use 2 layers inside and out). It has been constructed in 2 sections that bolt together for ease of transport. The patchy but smooth appearance is due to the use of glass bubble/epoxy mix as a final lightweight filling layer that has been sanded smooth. I plan to spray paint it white with a hard enamel paint when I get around to finishing it.
There appear to be 2 schools of thought when it comes to the final appearance for carbon fibre tubes - some like the appearance of the black carbon fibre (and is how most commercial tubes appear to be made). However, epoxy resin breaks down from UV exposure after time, and the black tubes will get very hot and may even reach HDT (heat distortion temperature) if not properly protected from the sun. For that matter, it wouldn't be advisable to leave any colour fibreglass product inside a car on a hot summer day (I ruined a tennis racquet that way once!). I prefer the traditional white look, and I think it may be more difficult anyway to have a clear look with sandwich core construction (if you want the tube perfectly smooth and round).
Regards,
David
Thankyou David for posting the pics..
looks like it will finish up like a nice tube..
I might end up going down the same road as you have and use E-glass fabric instead as it looks like 1/4 the price. Maybe not as strong or as light as carbon fibre but still lighter and more rigid than aluminium. Might also go for that nornex honeycomb foam for the core.
Yeas I have heard there is a problem with OTAs and UV radiation. I think it is a much better idea to actually paint it and protect it from heat and sun.
Thanks for all that info and I shall do some more research on it before I get into it..
I have noticed that Protostar make a epoxy impregnated craft paper tube, I wonder if anyones tried making something up similar if that would be possible? Sounds rather easy and cheap as kraft paper is cheap and maybe put in a layer of E-glass over the top to strengthen it.
I suppose the hardest bit would be wrapping it around nice and tight and not tearing it or putting big wrinkles in it?
How do you make a carbon fibre OTA?
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