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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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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