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 Post subject: Carbon Fiber Frame?
PostPosted: July 27, 2013, 2:22 pm 
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I been looking into Carbon Fiber because not only am i interested in making my own body panels from carbon fiber but i been interested in building my own ram air intake system for my daily car because most ram air kits are made from plastic and never seem to fit right or not as easy on the eyes.. so its been just something i been interested in learning.. Well after some thinking i remembered reading about one guy who built his own bicycle frame after buying a $900 dollar road bicycle and hitting a bump that split the aluminum open causing the frame to be unsafe to ride on anymore.. Well after returning it to the manufacture he decided to build his own frame and decided to build it out of carbon fiber...and built the entire bike for less than $900 using carbon fiber for the entire frame as structure

What he did was he epoxied and glued the frame together out of PVC.. then where all the bearings and axles needed to go through he epoxied them to the pvc frame and then after getting everything where he wanted it.. He wrapped the frame in 3 layers of carbon fiber around all the parts and around all the pvc pipe...

He says he has put 2500 miles on this bike with him weighing in at 195lbs and he has yet to have anything give or break.. so what do you guys think about building a frame out of pvc first.. then when have everything situated you wrap it all in carbon fiber and never have to worry about painting it or it rusting.. and from what i understand about carbon fiber.. its stronger than steel...

He said he used 2 inch and 4 inch cloth to wrap the frame with..

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 Post subject: Re: Carbon Fiber Frame?
PostPosted: July 27, 2013, 4:20 pm 
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I have been testing this myself. What I have found is that PVC will laminate off, eventually compromising the strength. However, by using oak or ash boards (I used 1x2 boards) the epoxy will bond the carbon fiber weave to the wood space frame, increasing the overall strength.


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 Post subject: Re: Carbon Fiber Frame?
PostPosted: July 27, 2013, 4:41 pm 
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Downix wrote:
I have been testing this myself. What I have found is that PVC will laminate off, eventually compromising the strength. However, by using oak or ash boards (I used 1x2 boards) the epoxy will bond the carbon fiber weave to the wood space frame, increasing the overall strength.


i dont see how the pvc has anything to say in the strength of the final product.. i thought the final carbon fiber structure is strong enough on its own.. the pvc is just there to have a backbone to structure the carbon fiber to.. i remember watching an episode of how its made and they made the entire sail boat out of carbon fiber which was able to withstand the high speeds across water without damage for the USA sailboat Olympic team.. when they made the tubes that formed the frame they used preformed foam in the shapes of the parts and wrapped it in carbon fiber.. then after it was cured they would dip all the parts in a vat of something that melted the foam out of the center.. this made hollow structure supports out of carbon fiber...

It would be ideal to make the frame out of foam and then wrap it in carbon fiber but i think that would be incredibly time consuming and difficult due to the foam being so fragile.. thats why i brought up the pvc method this guy used for his bicycle.. pvc is very cheap to buy and easy to use.. and all the parts where things need to connect to the frame can be easly epoxied to the pvc tell the carbon fiber is cured and takes over as the structure..

Image

If you look carefully in the center part of the boat that connects the 2 sides.. you can see tube structure.. those where the tubes it was displaying being made.. after all of them were made they would epoxy the tubes together then wrap the entire structure in carbon fiber forming the peace structured by carbon fiber tube frame..


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 Post subject: Re: Carbon Fiber Frame?
PostPosted: July 27, 2013, 6:09 pm 
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The frame will twist during use. Having an independently moving core within the spaceframe can add stresses over and above the road itself. Another alternative struck me, using foam tubing or rods, glued together.


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 Post subject: Re: Carbon Fiber Frame?
PostPosted: July 27, 2013, 9:18 pm 
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Downix wrote:
The frame will twist during use. Having an independently moving core within the spaceframe can add stresses over and above the road itself. Another alternative struck me, using foam tubing or rods, glued together.


how does it add stress when the carbon is WRAPPED around it


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 Post subject: Re: Carbon Fiber Frame?
PostPosted: July 27, 2013, 11:22 pm 
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storx wrote:
Downix wrote:
The frame will twist during use. Having an independently moving core within the spaceframe can add stresses over and above the road itself. Another alternative struck me, using foam tubing or rods, glued together.


how does it add stress when the carbon is WRAPPED around it

Precisely because it is wrapped around it. When it flexes, if the core is flexing independent of the main load bearing structure, it will transfer stresses in different, unpredictable ways.


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 Post subject: Re: Carbon Fiber Frame?
PostPosted: July 28, 2013, 12:10 am 
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Wouldnt the resin bond the pcv to the carbon wrap as a single structure.. resin adheres to plastic pretty good i know..


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 Post subject: Re: Carbon Fiber Frame?
PostPosted: July 28, 2013, 12:34 am 
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storx wrote:
Wouldnt the resin bond the pcv to the carbon wrap as a single structure.. resin adheres to plastic pretty good i know..

See, that was my original thought as well, hence why I did the experiment. I do a lot of PVC based work (weaving loom, hand cart, etc) so it was my first thought for experiment. Instead I had every test case delaminate after testing. It worked well for a month or so but then they all began delaminating. Very sad for me.


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 Post subject: Re: Carbon Fiber Frame?
PostPosted: July 28, 2013, 8:47 am 
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polyester or epoxy resin aren't the correct chemistry for bonding to PVC. You need something with a good bit of serious solvent that actually melts the surface of teh PVC for a good bond.

Still, I think a well laid, fully saturated cf tape would be pretty dang strong. Fully saturated is absolutely critical.

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 Post subject: Re: Carbon Fiber Frame?
PostPosted: July 28, 2013, 9:46 am 
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Sounds interesting, I would like to make my body panels out of carbon fiber also but I already have most of the steel frame. I have never make anything out of fiber glass or carbon fiber so it will be a first for me. Good luck!

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 Post subject: Re: Carbon Fiber Frame?
PostPosted: July 28, 2013, 9:52 am 
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CF if expensive compared to glass. Cut your teeth on glass first and save a whole lot of $$$

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 Post subject: Re: Carbon Fiber Frame?
PostPosted: July 28, 2013, 11:42 am 
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TooBusy wrote:
CF if expensive compared to glass. Cut your teeth on glass first and save a whole lot of $$$

carbon fiber is much more expensive than fiberglass but the benefits of carbon fiber stretches a mile long...

I was thinking of doing the frame out of carbon fiber because of the following:

1)
Read the following off the internet:
1 inch 3 ply tube 127% stronger than 1 inch mild steel tube
1 inch 4 ply tube 161% stronger than 1 inch mild steel tube
1 inch 5 ply tube 203% stronger than 1 inch mild steel tube
1 inch 6 ply tube 243% stronger than 1 inch mild steel tube
.............................................................................................
So from reading that building structure components from it is incredibly strong...

2)
Read on a go cart racing forum that a guy who builds go cart frames for a living decided to dabble into carbon fiber and this was the results:
1.5 ID inch steel tube frame is 33.1 lbs
1.5 OD inch carbon fiber frame turned out to 19.2 lbs

He said he used the same jig he uses for the steel frames...
The way he built his was he used a 1.5 inch steel bar that he wrapped with 2 layers of paper... He said he used the paper you buy at home depot for painting.. then he wrapped 4 layers of carbon fiber around while painting the surface resin while he wrapped it.
The reason he had to use painters paper as the first 2 layers was because when he tried to make it on the bare metal rod he couldnt get it off once it was cured... the paper shrinks slightly allowing the carbon fiber to slide off.. The ones that gave him trouble he said he would drop them in a vat of water allowing the paper to soak in water then the paper would tear as you pulled the carbon fiber off..

Then when he made the frame he used carbon fiber epoxy to glue the straight peaces together.. kinda like welding.. once he had the frame made up in the jig he wrap the entire frame with carbon fiber ribbon to covering up all the cut ends.

On the locations that mounting peaces needed he used aluminum peaces and epoxied them to the frame and then wrapped over the peaces with carbon fiber ribbon to build it into the frame as a solid peace.

3) no need to paint... All the years i had sport bikes the most annoying part was paint and maintaining the paint from wear, scratches, and environment causing corrosion on aluminum parts and such... with the carbon fiber frame makes rust a thing of the past and the look of carbon fiber is beautiful. so no need to paint it so you save hundreds on prep and paint or powder coating..which in turn reduces the cost of the frame cost slightly...

4) power to weight benefit...
If 33.1lbs was reduced by roughly 42% to make a 19.2lb frame..
if a normal frame is roughly 80lbs... if it reduced it by 42% also that would put the frame at 46.4lbs
then when you do the body plates and floor in carbon fiber then the weight is kept low possibly makeing a fully bodied frame closer to the origional frame weight of 80lbs instead of 150ish pounds..saving you weight...


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 Post subject: Re: Carbon Fiber Frame?
PostPosted: July 28, 2013, 4:50 pm 
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Jeez! You are just barely started and 'Locost' is so far behind you can't even find it on radar!

Interesting theory though. Go for it and keep us updated.

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 Post subject: Re: Carbon Fiber Frame?
PostPosted: July 28, 2013, 8:55 pm 
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Sounds exciting, look forward to you trying it out. My concern is you spend all this effort trimming 70-80 pounds out of the body, you'll want to be absolutely anal about every single component choice in the car (measuring weight vs performance), otherwise it doesn't make sense other than to say I have a carbon fiber frame.


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 Post subject: Re: Carbon Fiber Frame?
PostPosted: July 28, 2013, 9:16 pm 
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storx wrote:
1)
Read the following off the internet:
1 inch 3 ply tube 127% stronger than 1 inch mild steel tube
1 inch 4 ply tube 161% stronger than 1 inch mild steel tube
1 inch 5 ply tube 203% stronger than 1 inch mild steel tube
1 inch 6 ply tube 243% stronger than 1 inch mild steel tube
.............................................................................................
So from reading that building structure components from it is incredibly strong...


How does its stiffness compare? For a chassis I wouldn't care about strength if it has to be a lot heavier to be the same stiffness.

storx wrote:
3) no need to paint...


UV destroys the integrity of resin. For something structural I'd paint it.

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