carbon fiber

[SCOTT EVANS]

Also if you dont want to bag your airframe I have another great method that leaves a fantastic finish. Works without vacuum but as good if not better results and cheaper. In fact so good that Giant leap took the idea and is now making their Dynawind tubes with my method. I personally will say one thing about buying product beings it was mentioned. Sometimes people shop for price. I try to always find myself shop with those that support our hobby. Like Aerosleeve does. It was a product originally designed by them for our use. For fiber glass stuff like epoxy I buy from Mr Fiberglass. He is one of us as well. I use the mr fiberglass line of epoxy.

Anyhow good luck !! give a shout if we can help.

Conway

SO

I tried my first small tube with glass last night. I used this porous teflon coated release film instead of mylar. A little fabric on top to soak up the excess resin. Well where it didnt wrinkle looks nice 🙄

[Ken PlattnerParticipant]

Scott, did you use peel ply and then wrap it with duct tape or heat shrink tape?

Ken.

[SCOTT EVANS]

peal ply??? Dont think so? I rolled on 2 layers of 6 oz cloth,
saturated it, then a layer of this porous teflon coated release film (thats the name) then this fluffy fabric, then heat shrink tape, then I couldnt find my heat gun (and a hair dryer wasnt hot enough) Sooo
I put on duct tape over all of it. BUt I started from the center out, instead of from one end to the other. Whats Peel ply (tech. name?)
Maybe Ill pull out ALA Food Saver. I saw a sight where the laid all the layers on a flat table, wetted out the mat and rolled it all on at once.
Then bagged and vacumed it. 🙄 🙄

[SCOTT EVANS]

I sanded out the wrinkles and it reminds me of termite tracks in wood!
lol

[SCOTT EVANS]

hmmm

Second try not much better. Maybe Im using to much resin.

[Warren B. MusselmanModerator]

Do one layer at a time if you’re v-bagging and make sure you squeegee all the excess out of the fabric before and after it’s layed up. Then wrap your peel-ply tight so that there are no bubbles, next your breather and finally the v-bag – all of this needs to be as smooth and tight to the tube as possible before you start to pull the vacuum. Sometimes it takes far more than two hands to get it right – even then it can be difficult. I’ve found 2-3 people to be a minimum for a 4″ tube if you’re using the food saver method. (You need two hands generally to hook up to the machine and hit the vacuum button, and two to four or even more hands managing the bag as the vacuum is drawn. By the way, if you do it right with a food saver, you’ll still end up with two lengthwise seams where the bag seams are. If you don’t get things as absolutely tight as you can before pulling vacuum, you will get wrinkles.

Personally, I’m leaning towards the shrink-tape method for airframes these days. However, I’m intruiged by what the big boys in composites and the aerospace industry do. You do your entire layup dry and then using a special vacuum bag setup, you vacuum the epoxy through the fabric in the layup using what’s called resin infusion. The amount of resin is supposedly much more controllable. The fabric is wound on the mandrel under constant tension as it’s applied.

Kent at Giant Leap is making these new pre-glassed tubes using a constant tension application of the fabric to the tube. That technique intruiges me even without the resin infusion because using it you can manage multiple wraps simultaneously. If you can wrap under constant tension and wet out the glass as it goes on, you’d be set. The unfortunate thing about the new GL tubing is it isn’t strength-optimized they’re using one or two wraps of 10 oz or thereabouts and then wrapping with mylar. They leave way too much resin – I would guess possibly even twice the weight of the cloth or even more from the look and feel of it. The best thing about it is you get an essentially prefinished airframe with some glass on it. No where near as strong as convolute wound glass or even filament wound glass tubing so I wouldn’t use it for high performance projects.

The ideal fabric to resin ratio is somewhere between 40% and 50% depending on the fabric, weave, and weight of the fabric relative to the fiber size and fiber count per rove. For standard weave 5.6oz 3K carbon, 43%-48% is the supposed standard from what I’ve read on some of the composite lists I participate in. That seems about right to me though in practice it seems like it takes a lot of effort to get the resin down below 55% or so. You basically want just enough resin to fully coat every fiber without a drop more – from a strength to weight perspective. (The main thing that makes composites work is that the epoxy keeps the individual fibers and threads from moving relative to one another.)

If you want that glassy mirror smooth epoxy finish, you need to have a LOT of excess resin. Some of the finest composite builders lay up their tubes at the ideal resin/fabric ratio until they get to the final layer and they lay it up resin-rich and mylar wrap it for the mirror finish layer.

Warren

[SCOTT EVANS]

Well

Tonight Ill try both again for second layers. One taped and one bagged. Ill try REAL HARD to make every thing as tite as possible. The way I figure it, even if I sand out the wrinkles, and refill the grooves with epoxy. The breaks in the cloth will be offset from one layer to the other.
It will be stronger than quantum tubing and much stronger than if I hadnt done it at all. AND Ill be around that curve a little further. (Ill bet sleaves would be a little easier, you could crank down the ends and get them real tite)

Scotte

[SCOTT EVANS]

Would more than 1 layer (Like 2,3,4) of the upper cloth used to soak up exess resin help, in maybe it would wrinkle, and not let the lowest layer (the fiberglass) winkle?
Mylar is a more rigged material than this poris tefflon. Would that help?
How would the exess resin get out from under the mylar ???

se

[Conway StevensParticipant]

Scotte, Did you see my post above on the compression wrap method? It outlays exactly the method with Mylar sheet. Many people now use this and in fact is the method that Giant leap is using to do their new dyna wind stuff with. The epoxy is compressed in a uniform manor and excess is squeezed out the ends. Ive been doing this method for the better part of 8 or so years. I believe that Ken is using it to do his CF lay ups as well as a few other Locals. My Daughter did her 3″ Thor last year with the method. It comes out very nice. Worth a Try.

[SCOTT EVANS]

Ill have to get some mylar.

(yes but yor daughter has more experiance and isnt a hard headed man like me!) 😉

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