Right mandrel/mold for 90° bent carbon fiber tubes

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Right mandrel/mold for 90° bent carbon fiber tubes

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zeiss	zeiss posted 11 Years Ago HOT Topic Details
Group: Forum Members Posts: 8, Visits: 30	Hi all, i'm buying some carbon fiber sleeves like the one in the image.. roughly 20 cm right + a 90° curve + another 20 cm right with the diameter of 21 mm. Upon your opinion what's the best and simple mandrel to create.. A copper tube rounded with pipe insulation foam...? I read in some article that it could be the right solution.. I think only that it should not be so easy to take out the copper tube once the carbon fiber is cured.. I imagine a different solution, the opposite of the previous one. I would like to try to use a rubber hose of roughly 45 cm ( those used to water the garden). I do not know the technical term (I'm not native English speakers ..) The outer diameter of the pipe must be equal to that which you want to obtain less the thickness of the sleeve of carbon fibers. Then I would insert each of the two ends of the rubber tube two pieces of an adequate diametered rigid tube (aluminum stainless steel ...) for a length of about 15 centimeters into the rubber hose... Then I subdue the rubber tube by holding the ends of the two metal tubes and would insert it into a kind of template that keep it fixed and positioned so as to create the shape I wish. I_ once the carbon fiber is cured... i think that it could be more easy to take off the carbon fiber tube the mandrel.. First i could take off the metal pipe from the rubber hose..it should be easier than the first idea.. Tha pipe are straight... Then taking off the rubber hose from the carbon fiber tube created it should be not so difficult because rubber i think it's more easy to go in the curves than copper.... :-) What do you think about my idea...? It might work ..? This will be my first attempt in the world of composites .. Do you have any different ideas or suggestions..? Thank you very much for taking the time in answering. Attachments Curved tubes.jpg (2.8K views, 98.00 KB) Tags Carbon fiber curved tube mandrel sleeve tube
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Warren (Staff)	Warren (Staff) posted 11 Years Ago HOT Post Details
Group: Administrators Posts: 2.5K, Visits: 7.9K	With a curved pipe like that, a flexible material in the middle is pretty much your only option as you would struggle to remove a solid metal pipe around the 90 degree bend! Your idea sounds like it would work. You will need to release coat the hose so the resin doesnt stick to it. Its will still not be easy to remove but it should be possible with manipulation and a bit of muscle. Warren Penalver Easy Composites / Carbon Mods - Technical Support Assistant
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zeiss	zeiss posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 8, Visits: 30	Thank you very much Warren for your reply..! I agree with your thought.. As you have some time please reply to my email about the diameter of this tubes i've sent you last night.. As you can read i'm in doubt on what products to use for making 21mm diameter tubes.. If it's enough the 20mm diameter or if it's better to go to the 40 mm type.. As i read in a comment from another user (Chris) on the 20mm diameter carbon fiber braided sleeve, i'd like also to be more sure about lenght and diameter to buy.. It's seem reading that post that he has some problem to make 21mm tubes with the 20 mm version.. and he have less lenght that expected at the 45° angle.. So as soon as i'll be sure on the right diameter and lenght to choose i'll order materials. Thank you again for the help.. Zeiss.
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Warren (Staff)	Warren (Staff) posted 11 Years Ago HOT Post Details
Group: Administrators Posts: 2.5K, Visits: 7.9K	For ease of use id go with the 40mm because its easier to contract braided sleeve than it is to expand it. However, if you are looking for ultimate strength and an even fibre distribution, i would go for 20mm as expended to 21mm the fibre angle will be closer to 45 degrees so better for a more even tube construction. Warren Penalver Easy Composites / Carbon Mods - Technical Support Assistant
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zeiss	zeiss posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 8, Visits: 30	Ok.. Thank you Warren for your reply..It's clear.. 1) It's a little more difficult to work with the 20mm to adapt to a 21mm mandrel but i'll obtain the maxx strenght as the fiber are more close to te rest position at 45°.. 2) it's more easy to work with the 40mm and stretching to 21mm...but the final product has a littel less strenght.. as the fiber as less close to 45° ... Just a question about the lenght of a braided sleeve.. In the hypothesis that : 1) the surface area of the sleeve remain roughly costant through the extension limits pushing or pulling the sleeve.. 2) the lenghts you are selling are taken when the sleeve is in rest position (fibers at 45° no pull no push..) i think it should be correct to write that : Lx = Dres / Dx * Lres Where : Lx -> is the lenght of the sleeve at the diameter Dx i'd like to make Dx -> is the diameter of the tubes i'd like to make. Dres -> Is the diameter of the Sleeve at rest (without any force applied) Lres -> Is the lenght of the sleeve at rest (without any force applied) So for example if i'll buy 1 meter of Lightweight Braided Carbon Fibre Sleeve 40mm i'll have a sleeve of roughly : Lx = 40 / 21 * 1000 = 1904 mm On the other hand, if i'll buy 1 meter of Lightweight Braided Carbon Fibre Sleeve 20mm I'll have a sleeve of roughly : Lx = 20 /21 * 1000 = 952 mm Waiting for you reply.. Thank you very much.... Zeiss. Tags braided sleeve change. surface area diameter lenght
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zeiss	zeiss posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 8, Visits: 30	Hi, i find this silicone pipe that could be nice for use as a mold/mandrel (whit a metal tube inside in the right part to mantain it straight) That's because i've read that resin do not stick to silicone .. The question is... Is true or it is anyway better to use a release agent, and in the case you suggest to use in any case a release agent .. which one can be the most suitable for a silicone tube ...? thank you very much for your useful help.
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Warren (Staff)	Warren (Staff) posted 11 Years Ago HOT Post Details
Group: Administrators Posts: 2.5K, Visits: 7.9K	Theoretically those figures look about right. How close you get in practice could vary slightly. Silicone generally does not stick to anything but itself. Warren Penalver Easy Composites / Carbon Mods - Technical Support Assistant
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