How to make carbon tube ?

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How to make carbon tube ?

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wozza	wozza posted 12 Years Ago HOT Post Details
Group: Forum Members Posts: 688, Visits: 5.4K	That's good news. I think we must be in a parallel universe I spent the weekend doing a tank/seat combo for an old Fantic twin shock trials bike. Carbon Copies Ltd
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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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tauruck	tauruck posted 12 Years Ago HOT Post Details
Group: Forum Members Posts: 7, Visits: 5	I never went into detail reading all the posts but here's a simple way to make a tube. Before I get into the process you need to know that you'll need to do some finishing on the part. Go to your local Polystyrene supplier and buy or order a column (Bar of solid Poly) with the OD you need. Make up a crude rotisserie with a plank, two 2x2" pieces of wood and two long nails that go through the pieces near the top. Build the tool to accept the length of your column plus a little extra. Set up the column so that you can rotate it fairly easily. Wrap peel ply tightly around the styrene column using pins. Wet out the peel ply with your "Epoxy"!! and lay up the Carbon rotating the column as you go. Once you're satisfied it's all wetted out or you've added more layers (I usually calculate how much material will give me the thickness I want) you can leave the job for a few minutes. It drips a lot so you come back and rotate the piece spreading the resin to get an even layer. You can eventually let it cure and sand smooth for clear or you could lay up peel ply. After the job is cured pour acetone into the Poly core to dissolve it and carefully remove the inner layer of peel ply (you don't want to get stuck with the pins) and you should have a good looking duct on both sides.
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Drew Diller	Drew Diller posted 12 Years Ago HOT Post Details
Group: Forum Members Posts: 35, Visits: 199	Wanted to post again in this thread after trying something very useful on a recommendation from a friend who has much more experience than I do. Instead of a metal mandrel with a slippery insulator as I had posted about before, or a soluble mandrel (polysterene and acetone, above), try Polypropylene rod stock combined with a high temp wet epoxy or a reasonably high temp prepreg. If you look at a thermal expansion chart, note that polypro has a very high thermal expansion rate. It grows a lot when heated, shrinks a lot when cooled. I used a prepreg that cures at 250 F in one hour. My workshop was 60 F at time of hand layup. Based on the resulting ID of my carbon tube, the PP mandrel grew from about 31.75 mm OD to about 33.25 mm OD. I was thinking that I might have to stuff the whole affair into a freezer to really take advantage of the cooling contraction - on my way to the freezer in my basement I heard an audible pop, and suddenly I could twist the mandrel at one end of the tube with respect to the carbon. Not long after, a few more crack sounds, and I was able to pull the tube relatively easily. Here's the thing. The mandrel arrived straight from shipping - I haven't turned it smooth on a lathe yet. It has some scuff marks that are visible and can be felt. If I were to do this with an aluminum mandrel, no way would I have ever gotten things separated. As a bonus, epoxy doesn't stick very well to PP in the first place. Some of the excess that got squeezed out simply fell off when I disturbed it a bit. As a super bonus, the stuff is pretty cheap! http://www.interstateplastics.com/Natural-Polypropylene-Rod-PRONE.php Here's a result: http://dillerdesign.com/random/bike/testing/904217_10152767246300038_1814471181_o.jpg Edited 12 Years Ago by Drew Diller
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BoostSamurai	BoostSamurai posted 12 Years Ago HOT Post Details
Group: Forum Members Posts: 34, Visits: 413	That sounds like a great way to make CF tubes Drew. JZX World Forums
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Matthieu Libeert	Matthieu Libeert posted 12 Years Ago HOT Post Details
Group: Forum Members Posts: 955, Visits: 3.4K	Looks like a great way to make tubes Drew. So if I understand everyting you wrap the tube with prepreg, put everything in an oven to cure the carbon, once cures you put it in a freezer (if needed) and remove the PP tube. You didn't use an outer tube as a mould where the prepreg is pushed against, but just shrinkage tape or something like that? (picture) Thanks for the share of information 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	Matthieu - your description is accurate, and the shrink tape is release coated Dunstone tape. The guy who gave me the advice doesn't use prepreg, but the wet epoxy he uses cures between 250 F and 350 F.
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carbonfibreworks	carbonfibreworks posted 12 Years Ago HOT Post Details
Group: Forum Members Posts: 292, Visits: 4.5K	Thanks for the great tips, i tried using an alloy bar with reasonable results but will try some of the other methods next time. Chris
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