Tried making a tube with 3k Carbon Fiber and it comes out pinched in some places where the vacuum squeezed to it. I did 6 layers continuously wrapped around a 1 1/2 diameter aluminum rod. Applied peel ply w/ breather cloth and almost everything I do, I fail. I wrapped the peel ply once and I also wrapped the breather cloth which is where I think I made my mistake, but not certain if that was the cause of it or not. What am I doing wrong? Thanks.
Assuming you are using a mandrel, heat shrink tape should give a much better finish. Are you using pre preg or wet lay up? If wet lay up, you have to do your wrapping and vacuum when the resin is tacky rather than wet for best results.
No I’m not using a mandrel, and I’ve never used heat Shrink tape. I’ll have to read more into using heat shrink tape. Appreciate the info. I am using a wet lay up, and I did not know to let it get tacky first. That might be my problem. I will try that tomorrow.
I just re-read your post and you say you used an aluminium rod, this is your mandrel. The reason for letting the resin tack is to make it easier to handle, not as much sliding around on your mandrel. Heat shrink tape is brilliant for making tubes as is heat shrink tube. Check out soller composites as they also have braided sleeving that might help with your process. Practice makes perfect.
Also, when wrapping the fiber, you need to tension the fiber quite a bit. Id you do not tensionthe fiber, you get less compaction. The compaction will then be done by the vacuum, and that will compress the fiber, creating wrinkles.
If you make a jig where you can rotate the tube in, preferably hands-free (electric of some sort, or with a helper) then you have both hands free to attach the fiber, and roll it on with tension.
I would also probably opt for carbon fiber tape, in a narrow width. I have seen a jig which rotates the mandrel slowly, and 10cm (4") away from the mandrel a piece of threaded rod rotated. This was used to wind carbon fiber or glass fiber roving (just long fiber, buy it at someone who is doing sprayup) in a nice manner. (hold the fiber on one point on the threaded rod, and the rotation will move it nicely from one side to the other.)
IT all makes it easier to wind the fibers tightly. This is critical to avoid wrinkling. After the fibers are on, you can wind your peelply, or just release coated shrink tape (Airtech A575RC)
Okay I understand now. I’m a huge noob to some terminology. I am curious now to try the shrink tape so I’ll probably order some up soon. The braided sleeve I’ve been wanting to try too, but I wanna learn how to do it first with just the sheet CF I have now. I agree, practice def makes perfect. Appreciate it. Thanks.
Thanks for all the info. Ill try out the shrink tape and see if I can build a jig to keep everything tensioned a little better. Thanks!
One more question. Watched a video on the shrink tape process, and I kind of do not understand. Can someone elaborate? If I use the shrink tape, do I need to vacuum bag the part? should I let it get tacky first before applying the shrink tape? Do not know the process / steps to take because everything I’ve watched is about repair. Thanks.
The shrinkage of the tape does the compaction, so no, you do not need the vacuum bag. As for time to apply tape, you will probably need to experiment somewhat, but keep it onthe early side.
How would I layer it? Shrink tape is better for pre-preg I’m guessing correct? I would think using a lay up, the shirnk tape would squeeze access resin out and make a mess. What I meant by layering it is, do I put mandrel, carbon fiber, tape? Also the tape is not permanently on the part correct? I would need the CF visible.
If you use a shrink tape with release it will just peel off after cure. You need to use a heat gun to shrink the tape. This is where fibre - resin content is important. Too much resin and you end up with a bit of a mess. Expect to see some resin squeeze out with wet lay up. When you vacuum bag with peel ply and breather you have the same thing, excess resin is pulled through. You can still make a really nice tube with wet layup. Your layering idea’s are correct.
Take a look at this old thread:
http://www.compositescentral.com/showthread.php?t=3715&highlight=rocket+tubes
ok,
go and buy carbon fiber socks like the one below:
Cover all the tube with this material and tight up the 2 edges with ties:
After take the resin (vinyl or epoxy) and wet the carbon. leave it to cure and then 2nd hand and 3rd. When this done sand it with 100 and after with 400, 600, 1200 , 2000.
The results are super and you don’t have to spend nothing else.
Just remember that braided sleeve may not have the ideal properties for the tubes intended purpose.