How to make carbon tube ?

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How to make carbon tube ?

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carbonfibreworks	carbonfibreworks posted 12 Years Ago HOT Topic Details
Group: Forum Members Posts: 292, Visits: 4.5K	I need to make some carbon tube and suspect i need to make a mandrel in the lathe to lay the carbon over, what would be the best material for the mandrel ? i have some nylon and alloy bar, would i have any release issues ? Thanks in anticipation Chris
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Matthieu Libeert	Matthieu Libeert posted 12 Years Ago HOT Post Details
Group: Forum Members Posts: 955, Visits: 3.4K	there are several ways to do this. I quickly tested this system: - PVC tube cut in to halves (horizontal) - inner biketyre with releaseagent on it - put carbon around half slightly blown up tyre - put it in the pvc tube - close everything with ducttape - blow up tyre Got some good testresults but not perfect, need to perfect it, if I find the time. you could also work from the outside with some shrinktape: - Take a tube - Lay CF around it - Tighten it with some shrinktape - Heat the tape - Tape will shrink and add pressure - Remove tape - Give it a quick sand Its harder to get a perfect thickness and smooth finish over the entire tube You could work with a Silicone core: - take a tube - Cut it in half (horizontal) - Give it some thickness on the inside (thickness of CF) - pour silicone on the inside - Let it cure - Remove Silicone core and thickness you've added - wrap Prepreg for example around the core - Put it in the tube - Close the tube (with some clamps or rope or something else - Put it in the oven - Silicone core will expand and prepreg will cure. - Remove core - You have your tube Haven't found the right expanding silicone yet You could take a pvc-tube with inner and outerbag and vacuum it: - Like with the biketyre - Instead of adding pressure with a manual pump you vacuumbag the outer bag - This results in the innerbag expanding (like experiment with balloon or egg in a vacuumbox) - let it cure - Remove inner and outer bag - open to halves of the mouldtube Haven't tested my theory out yet but this might give you some ideas Hope this helps you a bit, maybe other guys on the forum have more/better ideas Matthieu Libeert Founder MAT2 Composites X Sports website: www.mat2composites.com
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Drew Diller	Drew Diller posted 12 Years Ago HOT Post Details
Group: Forum Members Posts: 35, Visits: 199	Here's how I do carbon tubes with prepreg: - Get an aluminum mandrel from Discount Steel or something. - Polish it, quite a bit. - Get some high temp release wax. - Roll a single layer of mylar around the length and circumference of the area where you'll apply carbon. Give a few mm of overlap. - The mylar should sort of "hug" the wax, and apply pretty evenly. Properly applied, it should be almost invisible. - Be sure the foot print of the mylar is longer than the carbon tube you're making. At no point should you bond to the aluminum, even if waxed. - Seal the mylar seam, and the two ends of the mylar area, with kapton tape. - Test your mylar tube: slide it around on the wax. You might see some small wrinkling; this seems to be okay. Overall the mylar should act like a tube of its own thanks to the kapton spine running along the length. - The kapton spine is to prevent epoxy from reaching the aluminum. Even well polished and waxed aluminum has been all kinds of grippy with epoxy in my experience, I lost a whole mandrel, twice! - Lay up your carbon plies on the mylar. I imagine you could do this wet. - Apply shrink tape, I use Duntone. - Heat! - After epoxy has cured, let your mouth agape as you see how comparably easy mylar lets the tube slide off. It is still a muscle taxing exercise. EDIT: You will find that the non-stick side of the kapton will adhere to the innermost epoxy. It doesn't stick too much though, and can de slowly picked away using something long and thin. The mylar sticks almost not at all to the epoxy. If I need a tube to be empty inside, with a little faffing around I can eventually get it naked. Edited 12 Years Ago by Drew Diller
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