Other Wet layup composites, is carbon even worth it?

[Cannibal]

Does anyone have any real insight on strength of material, quantities of material needed, and what kind of weights comparing some typical products we would use such as 1708, 5.7oz carbon (twill or not), 6oz s-glass and 6oz e-glass, maybe some 5oz kevlar too? (all things available at Us Composites) to achieve similar strength?

In each case, does the advantage always go to carbon? Keep in mind the fact that we are talking about a wet layup, no autoclav, no baking, just a paintbrush, roller, and maybe some release film and a squeegee.

Can your home guy actually take advantage of carbon's properties in this case, where you are going to have too much resin left over to reach full strength, especially when looking at the additional cost?

For the sake of keeping things consistent, lets use building a tray from scratch as an example (say 14" x 24") if anyone wants to get specific on quantities and weights of a given size (which would be awesome).

I'm really hoping some of the composite gurus on here can enlighten me some.

 

[WFO Speedracer]

Depends on what we are comparing exactly, if we are comparing wet layup fiberglass vs wet layup carbon fiber the carbon fiber will always be stronger. Same goes for vacuum bagged or resin infused parts, the carbon fiber or Kevlar version will be stronger than the fiberglass part.

 

[Cannibal]

Ya, wet layup to wet layup. I understand the carbon will be stronger given the same weight, or be lighter given similar strength layups (or be stronger and lighter if done right), but by how much? With the cost of carbon, and our home practices, are we really talking land slide differences here? I can't seem to find any type of table giving this type of information.

I mean if I'm going to layup 3 layers of 6oz e-glass or 3 layers of 5.7oz carbon, I know the carbon is going to be stronger, and need less resin, however, with wet layup, getting that resin to cloth ratio is nearly impossible without vacuum bagging and soaking up the excess. All this at a cost that is 5x or more greater.

I'd love to know, given the tray example I gave; Lets say I was going to lay up that 14x24 area with 3 layers of 1708. How much 5.7oz carbon would I need to get the same strength, and how would my weight compare?

 

[WFO Speedracer]

The strength of E-glass is about (3.45 GPa) and carbon fiber is about (3.53 GPA for carbon T300) as you can see they are very close strengthwise. Carbon fiber is lighter however @ $ 1.75 g/cc vs. 2.5 g/cc for glass.

 

[NVJAY775]

Good questions for sure. I have heard that there are different qualities as far as strength goes on carbon materials, and USComposites stuff isn't the toughest unfortunately. I do not know who's is better, so hopefully others can chime in on whos is worthy and available.

Without vacuum what I have been doing with cloth is this. I have a nice thin sheet of stainless that I lay my glass on. From there I will pour on and brush in the resin on one side, then flip the glass. The do the same from the other side, but will also use a bondo squeegee to get the needed resin penetration pushed in and then remove the excess with the squeegee. Works pretty good for not having the vacuum set up.

I seem to get good penetration and also get most of the excess out for weight savings.

Wish I had a better answer for ya...

 

[kevbo]

Ya, wet layup to wet layup. I understand the carbon will be stronger given the same weight, or be lighter given similar strength layups (or be stronger and lighter if done right), but by how much? With the cost of carbon, and our home practices, are we really talking land slide differences here? I can't seem to find any type of table giving this type of information.

I mean if I'm going to layup 3 layers of 6oz e-glass or 3 layers of 5.7oz carbon, I know the carbon is going to be stronger, and need less resin, however, with wet layup, getting that resin to cloth ratio is nearly impossible without vacuum bagging and soaking up the excess. All this at a cost that is 5x or more greater.

I'd love to know, given the tray example I gave; Lets say I was going to lay up that 14x24 area with 3 layers of 1708. How much 5.7oz carbon would I need to get the same strength, and how would my weight compare?

It is very easy to figure when the fiber is loaded in direct tension or compression. Bending loads the resin almost entirely and that is the main loading in boats. Carbon produces stronger short beam shears than glass does with the same resin. So a flat carbon pannel of given thickness will weigh less and be stiffer/stronger than glass regardless of ply orentation. This explains why SMC and nano clay can produce acceptable performance in boats. You can find lists of specific gravity for many materials on the net.

 

[harris414]

I have just started learning composite's and its turning out to be fun... and itchy...
I can supply you with some biaxial carbon fiber .024" thick if you like
Its left over from a local aerospace company and am told its as strong as ill ever want/need

Like stated above, I went by a glass shop and got 2 large pieces of glass to do my flat parts, and squeegee
out each layer going in the same direction, lay top glass on and add little weight, makes a real nice plate...
o and i have non stick layer on bottom and top so it doesnt stick to glass...

Its amazing how light and stiff this stuff gets...

 

[Waternut]

No one ever listens to me when I talk about the differences between kevlar, carbon, and glass so I won't bother. However, if you want cheaper/high quality carbon, go to www.sollercomposites.com.

 

[sportfish258]

What did he say ...

 

[TOBY]

Call th man

 

[Cannibal]

Thanks for the input everyone. I guess is there any way for us laymen to figure out how much of a given cloth one would need for say, the tray example, bottom of a hull, pole mount area, etc. I'd love to see some real world info from some builders giving the rest of us some hints about how much material is actually needed for different applications.

No one ever listens to me when I talk about the differences between kevlar, carbon, and glass so I won't bother. However, if you want cheaper/high quality carbon, go to www.sollercomposites.com.

Do you have any links to some of those topics no one has listened to you on? I'd like to take a look.

I have just started learning composite's and its turning out to be fun... and itchy...
I can supply you with some biaxial carbon fiber .024" thick if you like
Its left over from a local aerospace company and am told its as strong as ill ever want/need

Like stated above, I went by a glass shop and got 2 large pieces of glass to do my flat parts, and squeegee
out each layer going in the same direction, lay top glass on and add little weight, makes a real nice plate...
o and i have non stick layer on bottom and top so it doesnt stick to glass...

Its amazing how light and stiff this stuff gets...

That would be great! Let me know how much you are asking.

 

[harris414]

Just shoot me a pm when you think you know about how much you need, It will be cheap
and like I said its right from an aerospace company so its not cheap by any means

The material is a biaxial carbon, -45/45 deg.
I did a carbon ride plate for my 750sxi as one of my first projects, I layed up 4 layers and im sure it was
strong but had more flex than i wanted for the ride plate, so i layed up one with 8 layers and its super strong
and has almost 0 flex... the stock plate was over 3 pounds, the carbon is .43 pounds!

Im in the process of doing a test piece for a carbon hood, Looks like 4 layers will get the job done.
has strength and just a little flex like a stock reinforced hood.

Only use epoxy resin with carbon fiber
and I have found vacuum bagging a must when doing composite work... parts come out sooooo much nicer and stronger...

 

[snowxr]

My personnal oppinion (after building my own carbon hulls, and numerous other composite parts) is that if you're not going to vac bag or compression mold your layup, don't waste your money on expensive carbon or kevlar cloth. You'll never come close to the intended strength or resin to cloth ratio. The strength vs. weight depends very much on the RTC ratio, and extra resin doesn't increase strength. Building your own vac bagging system isn't all that expensive, and will even allow you to employ resin infusion. I have two of these setups, and they are worth every penny. A small up front investment will allow you to exploit the benefits of carbon vs. glass.

 

[WFO Speedracer]

All this talk of vacuum bagging and resin infusion is great if you are building new parts on mold set up to do vacuum bagging with, it doesn't help out someone like Cannibal who is trying to lay up a tray area on the ski, that would be extremely difficult to vacuum bag. I went back to the drawing board on my molds and made a lip so that I could vacuum bag the parts and yes you are correct there is no comparison in quality. That being said on something like a tray area I would rather be a little resin rich and have carbon fiber for the stiffness than to tryand get the same stiffness with Fiberglass cloth JMHO.

 

[XJCrawler]

No one ever listens to me when I talk about the differences between kevlar, carbon, and glass so I won't bother. However, if you want cheaper/high quality carbon, go to www.sollercomposites.com.

Weren't you the guy claiming the carbon Kevlar isn't anymore flexible then just plan carbon fibre!? Hahaha

 

[Schmidty721]

No one ever listens to me when I talk about the differences between kevlar, carbon, and glass so I won't bother. However, if you want cheaper/high quality carbon, go to www.sollercomposites.com.

Per Nut's recommendation this is where I sourced all of my carbon & kevlar too. By far the cheapest site I found for first quality material and lots of options for weights, weaves, etc in carbon.

 

[snowxr]

WFO, vac bagging reinforcements to the tray or the insides of a hull are rather simple. no mold is needed.

 

[Waternut]

Weren't you the guy claiming the carbon Kevlar isn't anymore flexible then just plan carbon fibre!? Hahaha

Love it. I didn't say a word about composites and even still people are trying to twist things around and put words in my mouth. Would love for you to find where I said that...

 

[harris414]

WFO, vac bagging reinforcements to the tray or the insides of a hull are rather simple. no mold is needed.

x2

 

[WFO Speedracer]

WFO, vac bagging reinforcements to the tray or the insides of a hull are rather simple. no mold is needed.

Actually that depends on how you cut your tray out, if you just cut out the bottom then yes its pretty simple, if you also cut out the sides and widened the tray then yeah not so simple, also to those of us who do vacuum bagging on a a frequent basis, yes it is a simple process, to those that have never done it again not so simple. I find your statement way too general in nature. :27: