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How to apply carbon veil?

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Old 09-06-2011, 11:48 AM
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rg1911
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Default How to apply carbon veil?

I had read that some people, especially those concerned about weight, are using carbon veil instead of glass cloth. So, I bought a bunch of .3-ounce carbon veil from CST for my current project.

Starting with the rudder, I discovered that the veil is not good about following curves, such as the rounded trailing edge.

Is there a trick to getting carbon veil to follow curves, or do I need to go back to glass? (I've asked CST, but have not received a reply.)

Thank you for any suggestions.

Cheers,
Richard
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Old 09-06-2011, 01:23 PM
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Default RE: How to apply carbon veil?

There are a couple of techniques that might work.  You might try misting the part to receive the veil with 3M Super 77 spray adhesive.  Then you can lay on a slightly over-sized piece of veil, press onto the shape/surface, trim of the excess, and then wet out with resin.  The other alternative is to use a vacuum bag to press and hold the veil in place until the resin cures.
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Old 09-06-2011, 01:55 PM
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Default RE: How to apply carbon veil?

Many thanks for the suggestions. I'll try the 77 spray adhesive (since I have some). I do have a used vacuum bagging system I haven't used yet, so I'm not sure that it works. And I suspect I should try something smaller than a 6-and-a-half foot fuse.

Cheers,
Richard
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Old 09-07-2011, 06:39 AM
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Default RE: How to apply carbon veil?

I did some experiments with carbon veil and found there were 2 problems when trying to use it to cover a traditional built up and balsa skinned plane. One you have discovered is that it does not drape well. The other is that it absorbs epoxy like a sponge and leaves a very noticable texture leading to a heavier finish than .5 or .75 oz glass. The light stuff has a lot of voids that need to be filled. I think where it is most used is in vacuum bagging where the pressure helps with both these problems.

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Old 09-07-2011, 06:55 AM
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Default RE: How to apply carbon veil?


Quote:
ORIGINAL: saramos

I did some experiments with carbon veil and found there were 2 problems when trying to use it to cover a traditional built up and balsa skinned plane. One you have discovered is that it does not drape well. The other is that it absorbs epoxy like a sponge and leaves a very noticable texture leading to a heavier finish than .5 or .75 oz glass. The light stuff has a lot of voids that need to be filled. I think where it is most used is in vacuum bagging where the pressure helps with both these problems.

Scott
Agreed. I don't use the stuff at all because you get pretty poor fiber:resin ratios.

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Old 09-07-2011, 07:20 AM
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Default RE: How to apply carbon veil?


Quote:
ORIGINAL: saramos

I did some experiments with carbon veil and found there were 2 problems when trying to use it to cover a traditional built up and balsa skinned plane. One you have discovered is that it does not drape well. The other is that it absorbs epoxy like a sponge and leaves a very noticable texture leading to a heavier finish than .5 or .75 oz glass. The light stuff has a lot of voids that need to be filled. I think where it is most used is in vacuum bagging where the pressure helps with both these problems.

Scott
That's interesting. I first saw the veil being used as covering in an article about control-line stunt planes. I had thought they were very concerned with weight. Vacuum bagging was not mentioned in the article.

None-the-less, it does look like I need to go back to glass cloth.

Many thanks for all the information.

Richard
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Old 09-07-2011, 04:29 PM
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Default RE: How to apply carbon veil?

I've heard it mentioned in the same or similar use on a video I have on molding balsa. They may have even suggested its use for reenforcing relief cuts. I suppose it could be the technique that I used as well. On the other hand, most of what I've read and seen on carbon composites has been vacuum bagged. I did use a couple of layers of carbon veil to reenforce the engine mount box on a Top flite Spitfire. I had to extend the box to accomodate the enigine I was using. It used a lot of epoxy to fully cover the carbon. It also felt spongee before it was set. Cost is another consideration. It's definately more expensive than .5 cloth. I still have a roll or two of the stuff waiting for an apropriate use.

Scott

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Old 09-07-2011, 04:56 PM
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Default RE: How to apply carbon veil?

Scott,

Thank you for the added information. Since I don't plan to get into vacuum bagging yet, it looks like it's back to glass cloth. Haven't decided on .5-ounce or .75 ounce, which I hear has a tighter weave and uses less resin.

And I'll have a total of about 15 yards of assorted carbon veil to use to reinforce areas. Should last me 20 years or so.

Richard
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Old 09-08-2011, 05:03 AM
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Default RE: How to apply carbon veil?

Quote:
Since I don't plan to get into vacuum bagging yet, it looks like it's back to glass cloth.
Now that's a relief.
For a moment I was worried that you were going to put your whole fuselage into a vacuum bag and compress the whole thing. []
(Would take up a lot less space in the bin, though.)

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Old 09-08-2011, 05:49 AM
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Default RE: How to apply carbon veil?


Quote:
ORIGINAL: Magne

Quote:
Since I don't plan to get into vacuum bagging yet, it looks like it's back to glass cloth.
Now that's a relief.
For a moment I was worried that you were going to put your whole fuselage into a vacuum bag and compress the whole thing. []
(Would take up a lot less space in the bin, though.)

Magne
And I wouldn't even have to go through the trouble of flying it into the ground.



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