How do you fab carbon fiber, anyone? Options

[914Timo]

BTW, look Gunnars´s fan shroud mold. It is beautiful (like all they do) ..... :sweet:

[JWest]

You might think twice before using CF for door panels.

In composite aircraft, CF is not used in the cockpit (kevlar instead) because of the danger of a broken CF piece.

If your car was to get hit, the door panel could shatter and the CF could do MAJOR bodily harm as it is razor sharp and splinters in a real nasty way.

Another tip if you are working with CF, use air drills rather than electric. The carbon dust from cutting CF can short out electric tools because it is a conductor.

[URY914]

Thats it-forget the CF door. I'll use my nice cheap 2 oz. f/g cloth. Two layers, with another 1" wide layer around the edges. I've taken pictures of the when I made the mold for the door and I'll take some more when I lay up the door. I'll show the whole process, step by step, just like Gunner. (Ha! I wish.)

Paul

[914Timo]

Sounds good idea Paul. Dont waste your money to CF.

But, if you like, please send more pics. I am big fan (IMG:style_emoticons/default/aktion035.gif) of your super light racer and I always like to see more pics about it. It would be nice to see pics about your FG molds and parts too. (IMG:style_emoticons/default/mueba.gif)

[Zeke]

You might think twice before using CF for door panels.

In composite aircraft, CF is not used in the cockpit (kevlar instead) because of the danger of a broken CF piece.

If your car was to get hit, the door panel could shatter and the CF could do MAJOR bodily harm as it is razor sharp and splinters in a real nasty way.

In that case, Kevlar would be the hot ticket, no?

[JWest]

Except Kevlar is expensive, ugly, and hard to work with.

[Jeroen]

From the little I know about it, Kevlar is used for impact protection (read the "canoo" post and it is used for bulletproof vests etc.) and Carbon is used for structural rigidity.

If you want your piece to work both ways, you could laminate the together...

cheers,

Jeroen

[Jeroen]

BTW... Timo, that fanshroud looks absolutly awesome!!!
Nice work agian!

cheers,

Jeroen
(another Gunnar junkie (IMG:style_emoticons/default/biggrin.gif))

[JWest]

If you want your piece to work both ways, you could laminate the together...

Yep - outer CF skin -- Kevlar inner protective layers.

345 tires all around on 20" full chrome rims

Did someone say 20" Chrome?

(IMG:http://www.truckxpressions.com/images/wheels/spintek_ICE882.gif)

[TMorr]

Typical CFRP race car construction, for safety, which is now almost all components, uses primarily carbon fiber, with a percentage of high tenacity, low modulus fiber to act as basket to restrain the broken carbon fibers. (Kevlar, Dyneema, Spectra)
In a monocoque design, elements like the nose box are intended to fully obliterate, absorbing a huge amount of energy. Retaining the nose stucture to the mass of the car is critical to achieve this full effect.
By the time the impact is beginning to encroach on the driver cell, the crash is pretty serious and the obliteration of the monocoque could be disasterous, especially in the case of multiple impacts. For this reason, Kevlar, but even more effective, Dyneema, is used with the carbon fiber to act as an anti penetration barrier. The high tenacity fibers allow the carbon fiber to crumble, absorbing a huge amount of energy, but retain the mass of the structure around the driver, offering at least some protection in multiple contacts.
Most people proabably recall the horrific footage of Stan Fox at Indy, where he was effectively a driver strapped to a seat back tumbling down the front straight after an initial impact removed the front of his chassis. Modern construction techniques are specifically intended to reduce the risk of this kind of accident.
An Indy car monocoque is not as light as it could be, with manufacturing process, skin thickness, core thickness and weight and "other fibers" all mandated - For Safety.

For a club level project, assuming you have safe and adequate driver protection in the form of metal structures, the lightest and most cost effective panels, like door panels will be foam sandwich with either fiberglass or carbon skins depending on you budget.

A carbon or glass and foam sandwich door panel for a 914 would weigh about 2 - 2.5 lb without paint. This panel would be stiff enough to sanding block rub without significant deflection. The carbon will be stiffer, as a virtue of it's fiber stiffness, regardless of laminating resin or process.

Without using foam sandwich, the panel will be quite flexible and will require significantly more fiber weight before acceptable stiffness ( but still significantly lower) could be achieved.

Foam sandwich can be done at home using your shop vac and a plastic bag (not to laminate - only to bond the foam) and I am sure there would be many DIY web sites listing this kind of information. Other than bonding the foam, the whole job could be treated as a simple wet layup process and within the reach of most people. I am sure a 3lb door skin is something most people could make at home if they have the door mold at their disposal.

Regards

Hayden PTBT

[Mueller]

For the heat curing of carbon fiber parts, what is the temperature for curing?

I'm talking about non-critical parts, not making brake rotors (IMG:style_emoticons/default/smile.gif)
(yet, LOL)

I've got an oven and an adjustable electric vacumm pump that will pump down to about .2 megapascals (~2 bar)

I'd like to do the engine sheetmetal in CF if I go the horizontal fan route.....personally, I do not like the CF valve covers...they do not dissapate the heat enough IMHO

[TMorr]

Mike,

It depends on the resin system. Most of what you are familiar will be room temperature cure. Many of these will benefit from an elevated temperature "post cure" maybe 175°F, that will improve the resin properties and also raise the realistic service temperature.
Beyond the room temperature systems, are miriad of resins that have special process or use applications. For race car construction, pre-preg (pre impregnated fiber) resins are cured at 120°C and 180°C - 2 different systems. The higher the cure (or post-cure) temperature, generally speaking, the higher the service temperature.

There are some great LTM (low temperature mold) resins these days that will cure at lower temps (just above room temp), that allow greater lattitude in pattern construction, curing over a long time frame. Elevate the temp and these systems cure faster. In all cases, these can be post cured once removed from the pattern to achieve full mechanical properties and high service temp.
These systems have to be refrigerated, so can pose some logistics issues.

Primary factors to consider when chosing a resin system - what service temp do I need? what temp can my pattern tolerate?, there are many others, but these two initial questions head to to a specific group of products to make the additional choices.

Hayden PTBT

[anthony]

Does anyone ever watch Dream Car Garage on the Speed channel? In this weeks show they did a segment on how to make a mold for a fiberglass hood. They also showed how to make a vacuum bag for the mold.

[TonyAKAVW]

I've heard of Phenolic resin being used with Carbon Fiber (for re-entry vehicle applications). Is there any advantage to phenolic for general use?

-Tony

[Mueller]

Phenolic usage is great as an insulator between the manifold and the carbs...helps prevent heat soak so that the chances of vapor lock or fuel perculation is less likely to happen

[Jeroen]

Wow Hayden, thanks for posting. Great info!

I was just reading this about the new Carrera GT, which has a CF monocoque
It's cured between 6 and 8 bar at a temperature of 150 deg. Celsius for 8 hours

cheers,

Jeroen
(just adding some trivia info (IMG:style_emoticons/default/biggrin.gif))

[TMorr]

Phenolic resins have some of the highest service temperatures of any laminating systems. Unfortunately they have relatively poor mechanical properties, so their use is limited by this.
CFRP with phenolic is kind of oxymoron, the performance of the Carbon fibers is so high that it can not be utilized in a Phenolic laminate.
Fiberglass and Phenolic are a more reasonable match, as is Phenolic and cotton, which is the common thermal insulator for carbs, circuit boards etc.
There are some other resins with better combinations of properties and these are used for components like the carbon exhausts on the Ferrari's.
These resins, with names I can pronounce, but not spell have applications far and wide, I am sure including aerospace where they would have been developed.
Anything cured above 1 atm, will not have been under vacuum, but rather in an Autoclave, where multiples of atm. can be generated to squeeze the laminate for advanced consolidation.

Hayden PTBT

[jonwatts]

Hayden, do you need anyone to sweep up around your shop? Clean toilets? Anything? I'll work for free as long as I get to be within earshot of you (IMG:style_emoticons/default/smile.gif)








No, I'm not kidding. Look where I live (IMG:style_emoticons/default/laugh.gif)
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[Mark Henry]

Except Kevlar is expensive, ugly, and hard to work with.

Yep, my canoe was expensive and the finish is ugly.

But it weighs only 48 lbs (my buddys FG canoe rings in at 75lbs) and it's bullet proof. (IMG:style_emoticons/default/ph34r.gif)