Campy

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I asked this question in the composites forum, but did not get a reply.

What is the best adhesive to use to adhere CF to plywood ?

Articles I have read have said to use everything from thin CA all the way up to and including epoxy to secure the CF. I will be using CF strips/tissue to strengthen some joints and also CF tubes (I plan on running the push rods/nyrod through them and want them to double as stiffners also).

Thanks

JoeAirPort

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Med to Thick CA is better than thin CA IMO. Also sand the CF to make it adhere better. You could always true Pro-bond, Gorilla glue, or any other polyurathane glue. Epoxy is good, just heavier than the above.

campbec

Hi Campy,

I havent had a great deal of experience with Carbon Fibre so others may have better ideas. I have found that if the fibre is exposed thin CA is amazing but I heven't used it to mate with ply. When the fibre isn't exposed but the surface is keyed with medium grit 24 hour epoxy glues it to ply like $$it to a blanket.

Hopes this helps,

Colin

vicman

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Wow, I never heard the blanket analogy before[X(].
I use the strips to reinforce foam under fiberglass with z-poxy. As far as rods go the sanding idea is a must other wise I treat it just like I do balsa, depending on the joint determines the glue. For struts and braces I use thick ca. or spars in a foamy 5min epoxy. I have also used hot melt to hold the pivot rod on a stabilator with no problems so far.

Bill Jennings

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You must have then indeed had a very sheltered life mate.javascript:void(AddText(''))
jaRegards.
Bill.vascript:void(AddText(''))

saramos

I did a couple of tests with some .5 oz CF tissue as a subsitute for fiberglass covering. Perhaps you can find some usefull info in my results. I did not try any tests with thin CA.

I made some test wing sections and tried a couple of approaches. One used 30 min epoxy thinned with alcohol. The other using brushing lacquer. The first thing I found is that the carbon tissue absorbs a lot of resin and it takes a lot to fill. On one epoxy test, I applied the epoxy over the surface, squeegied it, and used paper towels to soak up all I could. I then tried to fill it with a sandable primer. After 3 coats without sanding between coats, the carbon still showed through and was not filled. On another epoxy test, I added a second coat of epoxy with microballoons. It looked like it would still take another coat with microballoons to fill!.
On the lacquer test, I applied 4 or 5 coats of lacquer, and it still needed to be filled. I found the epoxy gave a harder finish than the lacquer.
I have just about given up with the idea of using it instead of a traditional glass finish because the results of the epoxy and lacquer test sections were twice as heavy as a test section I did using .5 glass with epoxy. Perhaps if I can find a good filler, or for special strenght needs, I'll revisit it.

For your application, if these are plywood parts that are flat and being reinforced by a layer of CF, you might try vaccume bagging. I've not done bagging myself, but from lurking around the composites forum, this sound like a method that would work well for creating a carbon/plywood laminate while minimizing the amount of resin.

Scott

Campy

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Thanks for the information.

I now know the following:

1. Sand/rough up the CF to insure better adhesion.

2. CF is basically a sponge - it is going to soak up a fair amount of adhesive.

3. Since I will using this on plywood I will most likely go with thick CA or epoxy. The polyurethane glues sound good, however, they are expensive, have a short "bottle" life once opened, and I am concerned about their ability to adequately penetrate the plywood and whether or not they are going to penetrate through and block the tubes with their expansion.

Thanks again for the information.