CF: Form vs Function

[Blurred Talon]

Actually BlurredTalon, CF is stronger than steel, and I would prefer that over steel in an accident. Now if you are talking in an accident where roll bars are required.. well that's why the roll bars are required.

I'm not arguing that CF is stronger. It's just a steel door was designed with crash beams, these beams channel the energy away from the driver in a crash; that's all.

 

[xe0]

Definitely interested in "real" a.k.a made in an autoclave dry carbon parts but am fairly certain they will never be produced for dsms

 

[PotatoFlakeSTi]

Definitely interested in "real" a.k.a made in an autoclave dry carbon parts but am fairly certain they will never be produced for dsms

I'm sure someone would if offered enough money... Problem is supply/demand.

 

[MidShipCivic]

Definitely interested in "real" a.k.a made in an autoclave dry carbon parts but am fairly certain they will never be produced for dsms

Autoclaves that huge are expensive pieces equipment man!

 

[xe0]

Autoclaves that huge are expensive pieces equipment man!

One of the reasons that so few companies make parts in them. I would imagine that you would contract out that thing to one of the many airline industries that own giant autoclaves versus purchasing your own. Limited market in an even more limited and dying aftermarket for our cars .

Still interested to see what you can come up with. My Seibon "carbon" hood has bent from being propped on the hood for about 2 months, talk about "quality".

 

[GsXdSmKingGsX]

There are just certain colors that CF looks amazing with. (Silver, white, red)

If it wasnt any of those colors, I would paint it to match the car.

 

[Dylan0123]

I was asking mainly because I make CF/Aramid parts every so often for a mine I work for, and I came across a technique that *can* reduce cost quite a bit without sacrificing a noticeable amount of strength while still keeping the weight extremely low. We have tried it, and it works quite well. It's just not as pretty.

There's a possibility of manufacturing the parts people have been asking for, as 100% CF pieces, but not at F1 racing prices. Very few of us would be able to afford that. One of the problems is that t700/aerospace grade cloth in several weaves is becoming increasingly hard to purchase in smaller than 100 yard quantities, and I'm not in a financial position to drop $2800 for a roll.

I normally don't like using anything less than aerospace CF because the flexural modulus in commercial grade CF cloth is a ballpark guess, at best. If I made someone other than myself a part, I want the knowledge that the part is as strong as it possibly needs to be and isn't going to fail catastrophically and hurt/damage anyone or anything. That way I can sleep at night, and the people who use them are confident in the safety and quality of the part. In reality though, the strength of both aerospace and commercial CF is usually more than strong enough for most automotive applications. It's mainly just for my peace of mind.

The catch is that the "pretty" cloth CF look would be extra, not necessary. I can laminate it on as a surface layer on a few if it's something the person really has to have, but for automotive use, it's unnecessary.

If that isn't a major problem with the people potentially using the parts, then I'll continue setting up a few production molds and rigging up a series vacuum pump.

And to address the statement above:

Fit problems are more a result of using lower grades of epoxy. Some epoxies will shink a tiny bit OR can absorb more water than others. I generally stick to ASTM tested structural epoxy with a known shrink rate, which should be miniscule. When I vac a laminate something like a ballistic equipment guard, I leave a couple inches of surface for fiber outside of the mold lip, so final cut size is adjustable if needed.

Another factor is cure. If cured at a temperature under the epoxy's moment of fluidity while still contained under the vacuum used to form it, it will be exact to the mold used if stored properly after being demolded. This is assuming that the part is made with an appropriate resin though.

Finally, all carbon fiber matrixes have a little expansion/contraction that can be noticable along tight body lines, which can be minimized through epoxy type, but it's just an aspect of the material that you have to accept for the weight reduction. I personally don't notice it unless it's REALLY hot or cold outside, and it will normalize once the engine heats up.

As for the inconsistancies, you are correct. The widest roll of CF that I've heard of is 60" wide, and it's not cheap. That generally means the fabricator will have to use a couple pieces from a 50" or 42" roll to form something real wide, like a hood. If they don't bother matching the weave at the intersection and super gluing it in place so the vacuum bag doesn't move it much, there's an obvious visual change in pattern. Even gluing the join line doesn't always work.

I'm all about function over form. I think that most DSM enthusiasts are as well. I'd love to be able to pay less money and have something that works just as well but maybe doesn't look as pretty. My car is 16 years old and i bought it for $1200. I'm just looking to keep it running, and running fast. I think if you made a product like you described it would definitely sell well in this community.

 

[H@xtGSX]

I've been wanting a true carbon fiber hood and hatch for my GSX for a while (and fenders, and doors, and dash, etc). Instead, I have a hood and hatch that consists of a fiberglass shell with a CF top layer like everyone else. And I'd like the option to get them without the thick clear coating so that I don't have to sand it down by hand to paint it. I don't care of the weave looks perfect because I want to paint it. So long as it's strong and fits right, I'd absolutely love to see some less expensive options out there that can save just as much weight. Maybe then we'd see CF fenders for all DSMs, along with all kinds of other parts.

On a side note, I edited your post so that it doesn't violate our commercial posting policy. We don't want people posting threads for market feedback who aren't a Supporting Vendor - or at the very least, a Supporting Freelancer.

OK, I'll remember that. This is the 1st DSM I've owned and I'm still a n00b here, but I'll actually be contributing soon so I can do so. It'll be necessary eventually. My car is a 2ga, and it's what I'll be pulling my initial molds from, but it looks like there's next to nothing for you high power 1g's. I'll have to see about getting a few panels.

I'm currently doing the math for material and time for various parts, and setting up a small 10x20' shop (read ghetto ass shed...haha, it's clean though) in the backyard. If no one is offended by the lack of the CF cloth look, that's a good thing for everyone. Real CF parts do not flex much. Their rigidity is why they are so strong, and because of that characteristic, I've never had the vast majority of the problems people are having occur with aftermarket parts.

It's going to take a little while to get things working smoothly though, so don't expect to see anything for a few weeks, at least. I'll have it set up for vacuum forming, so no thick, goopy looking hand layup stuff. I'm used to working in a huge machine and plate shop with all the space and tools you could ever hope for though, so this will be an adjustment that's going to take some time. The first parts will be shown here for critique when I get some done to my satisfaction, and prior to anything leaving my possesion.

I'm thinking a set of fenders with a CF tubular shock tower stiffener attached with a bolt plate that extended back to near the door hinges would be pretty kickass myself... something for future research, for sure.

Addressing a few of the statements/questions above:

Impact resistance of CF parallel to the length of the fiber is excellent, initially, but if the force is even a little out of line, compression of one side or the other will cause it to fail via shattering. F1 cars have energy absorbing cylinders of CF that progressively transfer a bit of the impact energy around the structure of the entire car as they resist a progressing amount of force then they shatter. This allows it to sustain huge amounts of damage without the driver getting squished. As for CF on street cars, there's no highly engineered energy absorbing crush zones built into anything I've ever seen. Also, you're a whole lot more likely to sustain a lateral hit which would transfer energy to CF's weakest point, perpendicular to the grain of the fibers. They'll just snap. So shell CF doors wouldn't be a good idea. They'd likely just turn into a big shrapnel grenade in a side impact.... BUT, if someone were to apply that shell to the interior steel with the crash bar intact, that'd be a heck of a lot safer, and doable I would think.

As for weight.... there's NO COMPARISON to carbon fiber. Carbon fiber's density is about 1.75, fiberglass (E-glass, usually) has a density of 2.54, and steel is 7.9.
On top of that, carbon fiber has a tensile strength about 18-25% higher than steel. It's unbelievably light weight. You could lift a CF hood for an Eclipse with a couple fingers.

Also, the autoclave process is used for speed with a particular type of epoxy. For our purposes, an autoclaved part would perform no better or worse than a well made vacuum formed part.

 

[xe0]

Also, the autoclave process is used for speed with a particular type of epoxy. For our purposes, an autoclaved part would perform no better or worse than a well made vacuum formed part.

Do you have some data to back that up? Not calling BS just interested in the scientific reasoning (organic chemist <---).

 

[Corse]

Generally the CF door panels that I've seen are not something that I would trust for a daily as others have mentioned. Not to say that carbon fiber is not strong enough, but many of the people who manufacture the aftermarket panels make them for weight reduction and are not something that have gone through crash testing nor are they the thickness that should be considered for such an application. Most people that are going to run something like CF door panels in sanctioned racing like SCCA or those lines have also got the cage to back it up which is a different story.

There are instances where carbon fiber can be made strong enough but the difference is that where steel can bend and tweak, carbon fiber will hold rigidity and is brittle and will eventually break. A panel that is a mm or two thick is not something I would want to be plowed into from a ford f-350 on my daily driver. Not to say I'd like to get plowed from the side as it is...

Carbon fiber is very good for structural applications though. I enjoy making some stuff for my cars out of the stuff and it's fun to work with. It's actually very similar to fiberglass in many ways. A friend once told me "It's just fancy paper mache." and in a lot of ways it is. But to make something structurally worth it takes many layers, but it is such an easy way to lose weight.

I like it for it's aesthetic purposes as well, but of course... I like function over form.

 

[born2tune]

I love carbon fiber, replacing heavier parts with it would be awesome, painting it would be a plus as the clear coat lasts for 4-5 years max,under perfect conditions.

 

[Corse]

I can agree there. It's not crazy to paint either. A lot of people seem to go "WHAAAT?" when they hear about you painting it. But realistically a lot of companies that use it do paint over it on some stuff. Ducati is a good example. For instance on the xerox replica some years back the fairings were 100% carbon fiber, but they were painted over. There's no way you could tell unless you looked on the inside of the fairing where it was masked in a few places.

Nice shiny paint job.... or icky yellow once it's had enough exposure with time... unless you have crazy deep pockets and can afford that uv resistant gel coat, and that stuff isn't cheap.

 

[arrowhead]

Well I would have to disagree with most of you.
I have been working with fiber for over 40 yrs, I have built from boats to very small pieces and complete cars, I dont find it messy or difficult only you have to learn it properly.

As far as CF vs steel the reinforcements at the doors are a joke, with a very thin gauge of sheet metal and a flimsy bar running lengthwise there is not much impact absorption that is the reason newer cars now have to have side air bags, of course it would offer more protection than a CF or fiber door, the hoods are no problem they are design to crumble up on impact and also the engines to crumble down.

Please do not compare the extremes of F! or any other type of racing to our DD.

I am building now a RR car and I am going to the max on weight saving I want this to be the lightest car I have done.

CF vs fiber, unless you really like the looks IT IS NOT WORTH GOING WITH CF INSTEAD OF FIBER, the weight difference between the 2 is minimal, I can build a part out of fiber lighter than CF you just have to know what you are doing.

SO if it not for the LOOKS CF is not worth it, and maybe only for the 1st yr or so, specially on a RR car.

I made a post in another thread with the weights of the roof w the glass glass and w/o and my new fiber one yesterday.
specially on a RR car that takes a lot of beating
if it was, I would be making my parts out of CF and I have already tried.

 

[H@xtGSX]

I have worked with CF and Kevlar for ballistic guards for a while, and I've done fiberglass quite a bit also. Now, I'm not a 40 year vet with the stuff, but I have to contend a little. Fiberglass for daily use is tougher than CF is, but I don't think pure CF is a waste on daily drivers. IF you aren't purchasing the enormously over priced CF/Aramid honeycomb/CF racing panels some places are selling, pure CF panels with nearly as strong characteristics can be made for much less. We've made a couple and tried them out where I work. They aren't anymore expensive to make than what stores are charging for lamented fiberglass CF parts, and I know for a fact they're a lot lighter. It's no more difficult to make one of those panels than it is to make a fiberglass panel IMO. Strength ratio wise though, I think your off the mark. Fiberglass is 30% heavier than CF and requires about 14% more material than CF to reach comparable strength. Now, in automotive application, you may be able to get away with using less fiberglass because of it's greater flexural capacity, but it is not going to hold form rigidity and resist things like downforce nearly as well as CF in things like the convex structure of a hood. I'm not saying DD conditions are anything like F1, but that's the only place I see pure CF being used for entire car structures, so what else is there to relate it to?

Don't get me wrong, I actually agree with you for the most part. If I had to choose between an 8 ply 12k tow hood that weighed 8lbs vs 17 lbs of fiberglass when the price difference is $1200, hands down the fiberglass wins. CF usage and production is advancing though, and the use of the majorly expensive fabrics in anything other than the most extreme conditions is quickly becoming unnecessary. Unistrand, veils, chops, and bidirectionals are all much cheaper than cloth and perform as well if used right... in some instances they work even better. Just look at garbage truck drive shafts.

 

[arrowhead]

I have never made any anti bullet part but for DD and street cars turned into race cars, as far as deflection, I only made one hood for a 1980 firearrow which was buckling in the middle at high speed even NASCAR hoods flop at tracks like Daytona, talladega, I only added a rib to the center of that hood and problem solved and it happened because I am a weight nut., As far as a roof, laminar flow is minimal and you do not get deflection, much less on the hatchback, the fenders at least on a 2g they are not worth doing, they are very thin gauge and weight saving would be almost nothing.

I raced a Corvette which the front cap complete weighted only 17 pounds.

Weight of resins vary and it all depends how you do the lay up and what you are trying to make, the hood is the heaviest of all pieces, mine after taking all hardware off was 43lbs and my new fiber is now 8lbs it will gain a couple of lbs after the reinforcement.

I would not recommend doors to anyone unless is a pure track car, my gutted steel even after cutting the hinges in half and no closing latch was still 18lbs so it was still too heavy my new door is 7lbs and I know I can still make it lighter.
Even on race tracks with the dust and sand floating in the air, during a race the front of the car gets a nice sandblasting. being CF or fiber.

 

[MidShipCivic]

Please do not compare the extremes of F! or any other type of racing to our DD.

Your product end use intentions is not the entire forum.

Also, I strongly disagree fiberglass is not tougher than carbon the entire motorsport industry disagrees with you.

In the same sense no one needs an aluminum rod 750whp street car.

fiber, unless you really like the looks IT IS NOT WORTH GOING WITH CF INSTEAD OF FIBER, the weight difference between the 2 is minimal, I can build a part out of fiber lighter than CF you just have to know what you are doing.

In your sense fiberglass will flex more and be weaker, because you used less layers of it. Strength and stiffness properties are lower than carbon fiber to match it you will make the same part heavier.

You could flex fiberglass more without breaking it.

I would not recommend doors to anyone unless is a pure track car, my gutted steel even after cutting the hinges in half and no closing latch was still 18lbs so it was still too heavy my new door is 7lbs and I know I can still make it lighter.

There is nothing wrong with a carbon door at all some production vehicle have carbon floor pans carbon doors with a steel unibody. Some manufacturers use plastic panels ( (new lamborghini advantadore).

Some cars have aluminum doors to save weight.
Some cars have entire aluminum frames.

The same goes for carbon.

You can just stop the '' no one needs that for a street car'' thing .




Side impact on vehicles are the worst for obvious reason that little door bar in a factory car will not do anything for you. If you're looking for side impact protection this race car practice is the best you can get.

This is a incompressable foam pocket covered in kevlar ( best abrasion resistance).

You must be logged in to view this image or video.

The door frame and skin simply put; in composites it will be stiffer and stronger lean on it and it won't fold in like your factory door (if made correctly) & will be lighter.

Simply put the part is a better part in terms of weight, stiffness and strength it DOESN'T cost better.

 

[arrowhead]

The OP named this thread FORM VS FUNCTION.

I have stated facts and recommendations only.

I advise against a fiber or CF doors only.
I am not disputing the fact that CF is lighter.
I am not saying that it does not look cool.
For some people apparently not since they are painting over it.
I only pointed out the facts.
I never mentioned the racing industry.

NICE picture of that door on probably an 80k or more DD.

Is that a 1g or 2g.

I gave weights of the fiber pieces I made, could you please do same so we can compare apples to apples?

I can certainly see a lot of DD with that nice foam on their doors.

I am not in the industry are you?

I am only trying to build a road race car W/ a very limited budget and I have the ability and knowledge to work with either one of these materials and about 85% of the time go w/ fiber.
I currently have molds for spoiler on a Miata, rear 1/4 panels for 914 Porsche,complete roof for a 2g, naca ducts single and double, various sizes of funnel type ducts for brake cooling, also made my hood with 2 humps instead of 1 like the original.

Since you are in ORLANDO, FL., and I am in MIAMI I invite you down and if you like you can use some of these molds to use with whichever fabric you use.

I only do this as a hobby, been doing it for a long time for me and my racing friends.

Sincerely and respectfully yours.

arrowhead

PS: Also known to some of my friends as MOLD MAN.

 

[tonyseagle]

If you can produce strong CF parts that fit well, I could care less about inconsistencies in the weave, and I'm sure many others would agree. I'm about to pony up big $'s for a chaser CF convertible hardtop, and its got all sorts of weave inconsistencies, which I have no problem with as it weighs half as much as the fiberglass version, and I know fitment isn't an issue (been on another car already)
Peoples biggest gripes that I've heard with CF is fitment past the point of being cosmetic, to where permanent modifications has to be done to the car to make it work.

I'd check some reviews with that company before you buy from them. It took them 11 months to finally give me a refund on a hood they never had. Pain in the ass.

 

[gusu]

Directly from the SAE website.

"Side crash tests indicate that side impact bars play an important role of providing protection to occupants during the crashing processing. It can provide lateral stiffness of side structure and get more human live space. Therefore a good design of side impact bars will improve the crashworthiness."

Crash bars even, the first ones WERE accurately and thoroughly tested to reduce risk of injury in side impact collisions. Most work by deflecting away from the driver and passengers towards a different and harder part of the car.

Side impact bars don't have to be huge to do A LOT. Guard rails aren't very strong or very considering they can help fully loaded 18 wheelers on the road. Deflection is a much better way reducing chance of injury or death than just being able to stop a impact.

Do you think a rock offers better protection to your face than a pillow? If you are so stupid to think a strong piece of metal offers superior protection than a well designed weak piece of metal, please let me come over and smash your skull in with the rock. Maybe you get the picture now.

The reason they put such strong capsules in race cars instead of small OEM style crash bar is simple. The whole car is the point of deflection rather than the cage doing the protection. Those side impact bars like in the picture don't work because they are strong but because the rest of the car does the deflection.

Please if you don't know how roll cages and safety equipment in cars work don't offer even your opinion. This kind of misinformation can get someone killed. Yes roll cages for different style race cars are what is designed to absorb the impact and it does it well for what it is rated for. There is a reason why when you pass a certain point most forms of racing require a lot of different things. At a certain point a roll cage can no longer deflect the forces of a high speed crash by itself. Instead the cage is designed to absorb secondary lower speed collisions and the main deflection point becomes the body panels or even the frame of the car itself. It is very common knowledge that race cars explode into tiny parts for this reason. Most modern cars do nearly the same thing.

 

[arrowhead]

Directly from the SAE website.

"Side crash tests indicate that side impact bars play an important role of providing protection to occupants during the crashing processing. It can provide lateral stiffness of side structure and get more human live space. Therefore a good design of side impact bars will improve the crashworthiness."

Crash bars even, the first ones WERE accurately and thoroughly tested to reduce risk of injury in side impact collisions. Most work by deflecting away from the driver and passengers towards a different and harder part of the car.

Side impact bars don't have to be huge to do A LOT. Guard rails aren't very strong or very considering they can help fully loaded 18 wheelers on the road. Deflection is a much better way reducing chance of injury or death than just being able to stop a impact.

Do you think a rock offers better protection to your face than a pillow? If you are so stupid to think a strong piece of metal offers superior protection than a well designed weak piece of metal, please let me come over and smash your skull in with the rock. Maybe you get the picture now.

The reason they put such strong capsules in race cars instead of small OEM style crash bar is simple. The whole car is the point of deflection rather than the cage doing the protection. Those side impact bars like in the picture don't work because they are strong but because the rest of the car does the deflection.

Please if you don't know how roll cages and safety equipment in cars work don't offer even your opinion. This kind of misinformation can get someone killed. Yes roll cages for different style race cars are what is designed to absorb the impact and it does it well for what it is rated for. There is a reason why when you pass a certain point most forms of racing require a lot of different things. At a certain point a roll cage can no longer deflect the forces of a high speed crash by itself. Instead the cage is designed to absorb secondary lower speed collisions and the main deflection point becomes the body panels or even the frame of the car itself. It is very common knowledge that race cars explode into tiny parts for this reason. Most modern cars do nearly the same thing.

What year was that report from and how far back does it cover, maybe we could ask them to see the ones on the 2gs and give us their opinion as I stated before hoods will crumble up and engines will drop.
GET a tape measure or a ruler and measure from the edge of the hood, at least on a 2 g, go up 12" and you will see the deflection point on that hood.

 

[newalonguy]

I understand your guys concern of "not for a daily driver" but i also feel that unless my car has a cage (bar to protect my legs&lower body) i don't like ANY fiber or CF doors or uni body in an accident. I've been in many cars with CF and glass bodies and would NEVER want them to basically explode inward to me ESPECIALLY in a wreck on the track....In fact thats kind of why nhra requires cages on fast cars because the speeds they go, those little crash bars used for the street like to fold or fly off cars (doors flying off on the track) When you bounce off the walls at 120-130 MPH i would want more than some CF doors to protect my lower body. For a SHOW car CF doors with no cage looks......cool

 

[arrowhead]

I understand your guys concern of "not for a daily driver" but i also feel that unless my car has a cage (bar to protect my legs&lower body) i don't like ANY fiber or CF doors or uni body in an accident. I've been in many cars with CF and glass bodies and would NEVER want them to basically explode inward to me ESPECIALLY in a wreck on the track....In fact thats kind of why nhra requires cages on fast cars because the speeds they go, those little crash bars used for the street like to fold or fly off cars (doors flying off on the track) When you bounce off the walls at 120-130 MPH i would want more than some CF doors to protect my lower body. For a SHOW car CF doors with no cage looks......cool

I agree 100%, by the way I weighted the driver side door today and a complete door weights 87lbs that is a lot of pounds.

 

[glowryder]

i overlay CF, as well as make CF (full parts) and i can tell you this:

1. yes CF is stronger (in some aspects) then steel. Mostly in tensile strength. as for an impact like a CF door vs car, .. cf looses.

Overlays: overlays are great for parts that dont have much weight to begin with, like trip parts. It only adds a few ounces, and fits like OEM vs, 3m taping it on.

Overlaying large parts like hoods, is sill, it add alot of weight.. and is pointless

for this community, there isnt enuf interest/$$ to make full fledged CF parts.. the equipment, time, materials and r/d all cost ..Thats where overlaying (smaller parts) becomes cost effective, without adding alot of extra weight. A cf arm rest may way 8-10 Oz more then oem..

As for quality, it depends on the resins the use and the after treatment. Our parts dont yellow, b/c we invest more into the resins we use, giving the quality I and most of you expect..

bottom line:
Large parts: fenders, hoods, hatches, doors: if you cant buy them/arnt currently, then give up..as again it would really require alot to r/d, mfg etc these parts.. its not smart for compaines to do so..
Trim parts: get overlays, or if you like taping parts to your car, get the 100% CF stuff, in the either way, you stil have a 100% CF part, just the attachment is different.

Moral of the story: Most of the big gains, (hood hatch and doors) are already made and available.

 

[H@xtGSX]

i overlay CF, as well as make CF (full parts) and i can tell you this:

1. yes CF is stronger (in some aspects) then steel. Mostly in tensile strength. as for an impact like a CF door vs car, .. cf looses.

Overlays: overlays are great for parts that dont have much weight to begin with, like trip parts. It only adds a few ounces, and fits like OEM vs, 3m taping it on.

Overlaying large parts like hoods, is sill, it add alot of weight.. and is pointless

for this community, there isnt enuf interest/$$ to make full fledged CF parts.. the equipment, time, materials and r/d all cost ..Thats where overlaying (smaller parts) becomes cost effective, without adding alot of extra weight. A cf arm rest may way 8-10 Oz more then oem..

As for quality, it depends on the resins the use and the after treatment. Our parts dont yellow, b/c we invest more into the resins we use, giving the quality I and most of you expect..

bottom line:
Large parts: fenders, hoods, hatches, doors: if you cant buy them/arnt currently, then give up..as again it would really require alot to r/d, mfg etc these parts.. its not smart for compaines to do so..
Trim parts: get overlays, or if you like taping parts to your car, get the 100% CF stuff, in the either way, you stil have a 100% CF part, just the attachment is different.

Moral of the story: Most of the big gains, (hood hatch and doors) are already made and available.

I haven't really bothered doing any overlays. Never saw a need for it. 100% agree on the resins being most important. If you're not getting something with a high grade epoxy with a UV stabilizer, don't be surprised when it turns yellow next year.

My only point of minor contention is this: if you've done molding for larger pieces and have used a vacuum bag or pressure mold before, you know it's not very difficult to make a good replica of any part on the car. There's not much R&D necessary unless you intend to start some sort of fully automatic assembly line or are completely modifying some load bearing structural member. Reinforce the points of greatest deflection, as arrowhead suggests, and you are highly unlikely to break the part with anything short of a collision impact or brick of C4. Also, we aren't confined to cloth anymore. Cloth is overkill in many instances, which I'm sure you have noticed if you've made full CF parts before. It is ridiculously strong stuff. I've smacked 12k tow 2 ply bowed panels with a 5 lb sledgehammer as hard as I could and had the hammer bounce back and hit me with no visible effect to the panel... it was like hitting a piece of concrete. Cloth has just been available publically longer, so people are comfortable with it. There's quite a bit of research now with chopped, uni, and veil CF that supports the conclusion, just as with fiberglass, that the random distribution of chop or veil in an equivalent thickness is nearly as strong as fabric, and uni in shaft and uniformly loaded structural applications is superior to nearly any other material available. Unless you're building a ballistically rated part like a scatter shield or something, I see no need to continue using cloth CF for auto body applications other than aesthetics. It's expensive, especially when priced against an equivalent weight of chop. For small time producers like us, it is a slight shift in production technique, but allows us to make full CF for a small fraction of what a cloth piece would. If they are going to paint it, who cares if its chop or veil? It's just like fiberglass in that respect.

 

[glowryder]

It is when your doing parts that need "tabs", or mounting parts to snap in like factory. Apart from doing a 2 pc style mold for those parts, youll still end up making thim out of some sort of plasticine, and then infusing CF over top.. thats when time becomes the factor.. Even if you did make a 2 pc mold to make a 100% replica, and infuced it with CF, youll have to sell quite a bit of them to make back the costs.. Just making the "shell 100% CF is easy enuf, but then you get back to the 3m taping it on comment.. Im more into making the smaller parts.. as the big companies dont really want to waste time (yet) with the interior stuff when they can build hoods etc...

unless im missing something, i would rather not CA them to the back like ive seen some do on their 100% CF parts.. to me to do it 100% requires some nifty tooling and 2 pc molds..which d personally dont wanna bother with, as the scene is dying.. thanks economy..