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Old 02-02-2010, 05:51 PM   #11 (permalink)
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carbon fiber

I've only worked with pre-preg epoxy cloth.It required continuous refrigeration and documentation in and out of the refer.
We vacuum-bagged the material within tooling,the whole works inside an autoclave for the post-cure necessary to develop full strength.
It produced a fabulous part,extremely light for it's strength.Very expensive!
I know of only one person locally who works with the material.He does vacuum-bagged wet layups of experimental water ski's.He runs a ski service and can absorb expenses as a part of his business.
A certain university was given a large quantity of this material from an aerospace contractor and after considering the material,chose not to let the students to work with it.
Some consider it to be the new asbestos.
While I see the "promise" for the material,I doubt I'll ever use it again.I just cannot reconcile the expense over generic FRP.

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Old 02-02-2010, 05:58 PM   #12 (permalink)
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Quote:
Originally Posted by aerohead View Post
I've only worked with pre-preg epoxy cloth.It required continuous refrigeration and documentation in and out of the refer.
We vacuum-bagged the material within tooling,the whole works inside an autoclave for the post-cure necessary to develop full strength.
It produced a fabulous part,extremely light for it's strength.Very expensive!
I know of only one person locally who works with the material.He does vacuum-bagged wet layups of experimental water ski's.He runs a ski service and can absorb expenses as a part of his business.
A certain university was given a large quantity of this material from an aerospace contractor and after considering the material,chose not to let the students to work with it.
Some consider it to be the new asbestos.
While I see the "promise" for the material,I doubt I'll ever use it again.I just cannot reconcile the expense over generic FRP.
I agree, I'll just stick with polyester resin and T-shirts or fleece blankets for just about anything I need to do.
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Old 02-02-2010, 07:16 PM   #13 (permalink)
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my university also have a certain supply of carbon fiber cloth, while its true its dangerous to work with (dust is toxic and is conductive by nature, thus clogs and destroys power-tools) but as long as you work in a well ventilated area and where proper maskage. its safe. as far as cosmetic 2x2 twill versus standard cf, yes if you want to make it look cf pretty its going to be awfully expensive, but if you plan to paint over it, or just leave it raw, standard carbon fiber is rather inexpensive by comparison. but by far my personal favorite is vacuum formers (abs plastic) :-)
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Old 02-03-2010, 12:31 AM   #14 (permalink)
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An expert can get better properties from 'glass than an amateur can with carbon, except for stiffness. That is seldom needed except for structural parts, while it reduces toughness, which is what we normally want for aeromods. When I was building the all-composite integrated frame and suspension for my prototype - (see avatar background) Aircraft Spruce sent me a roll of carbon instead of aramid, and I sent it back, despite the chance for some cheap stuff. A lot of carbon gets used because it looks pretty and sells well, not because it is appropriate structurally.
You shohuld definitely practise on 'glass, because it goes transparent and you can check your technique. When you can get really high fiber content without voids, every day, you can graduate to opaque cloth. A lot of the difference in results with carbon is from using better resin and methods because the cost of the cloth seems to justify it. The same resins can be used on most cloth although mat often needs an ester resin to dissolve the binder.
Pre-preg is a nice clean process if you can afford it, but you can get the same fiber content using dry-bagging, with far less waste for bleeders, blankets, etc. Gougeon Laminating Resin is a nice low-viscosity epoxy that can be post-cured on a sunny day. Vinylester is better than cheap epoxy, most ways. It is just hard to buy because of a short shelf life.
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Old 02-03-2010, 12:12 PM   #15 (permalink)
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Their are more differences in the weave patterns other than looks. Fiberglass is available in the same weaves as well. Sometimes CF is woven with glass or aramid to get the desired properties (strength, cost, looks). Glass, CF & Aramid are also available in different grades, stronger grades are less stiff.

The main difference is in workability of the fabric. A standard 1x1 won't make a compound curve worth a darn. It's good for flat or 2D curves. You need larger spaces between the yarns to make compound curves.

One of the main reasons most people don't use FRP is the time & cost associated with the tooling involved to make molds.

I certainly agree about practicing with glass until you know what you're doing. If you're not careful you can end up with a very heavy part when doing wet layups.

As far as safety & tool ruining, Pros wear Tyvek suits, masks/respirators. They almost universally use air tools with vaccum hoses attached to them, or at least hold the hose near the surface to remove the dust.
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Old 02-03-2010, 12:15 PM   #16 (permalink)
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LOL - I still use t-shirts and fleece blankets, and a good 'ole can of Bond-O poly resin. It's worked out great for anything I've needed, but I wouldn't go building a boat with it. (Or would I? O.o)
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Old 02-03-2010, 02:48 PM   #17 (permalink)
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i certainly wouldn't use bondo on my car for anything bigger than a cracked plastic bumper
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Old 02-03-2010, 02:51 PM   #18 (permalink)
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You're thinking about Bond-O plastic filler. I'm talking about Bond-O poly resin, which is specifically designed for fiberglass repairs. They're two different products.

I don't use plastic filler for anything. I have other stuff I use to fill/level panels, but Bond-O's resin is the cheapest I've found in the quantities I need (next to nothing).

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