# Building your own Carbon Fiber Parts



## JACKofSPADES (Jan 12, 2014)

Hi All

I am new to MTBR so please Redirect me if i am on the rong Forum for this.

I would like to know how would you build a Carbon piece like the 
P-Knuckle on a rear derailleur. Like what carbon will be used and how would this part be molded or formed ? 








Please Help

Thanx
JACK:thumbsup:


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## mykle (Dec 25, 2013)

That is a really complec part to make out of cfrp. You will need multiple moulds and a vacuum system. Will be expensive for only making a few parts...


Fra iPhone


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## mykle (Dec 25, 2013)

Its hard to see if the fibres are continues on the pictures, can you see the fibres?


Fra iPhone


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## JACKofSPADES (Jan 12, 2014)

mykle said:


> Its hard to see if the fibres are continues on the pictures, can you see the fibres?
> 
> Fra iPhone


I cant see a definite patern of the threads but it seams to be more randomly spread.


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## Testmule (Jul 27, 2013)

From my own cf experience, which although is extensive, is only amateur, and hobby-based - I would say that part has probably been engineered by someone with a formal engineering background.

It isn't just fiber orientation. There are a large number of weaves, and quality levels (modulus) of cf, unidirectional being the strongest in one direction. The resin, which most people see when they look at cf construction is only the encapsulation mechanism that results in cf strength, and it is imperative that the optimum resin-cf ratio is achieved.

You can probably make that part, but you will have to do your research, and testing, on top of constructing molds and equipment. Vacuum pumps, epoxy resins, and cf are the easy part.

Paul


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## JACKofSPADES (Jan 12, 2014)

Testmule said:


> From my own cf experience, which although is extensive, is only amateur, and hobby-based - I would say that part has probably been engineered by someone with a formal engineering background.
> 
> It isn't just fiber orientation. There are a large number of weaves, and quality levels (modulus) of cf, unidirectional being the strongest in one direction. The resin, which most people see when they look at cf construction is only the encapsulation mechanism that results in cf strength, and it is imperative that the optimum resin-cf ratio is achieved.
> 
> ...


Ok cool

So what would your opinion be on this ?








Clearly you can see the Carbon threads (on the same part)

How would you make that ?

Thanx for Help:thumbsup:


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## Testmule (Jul 27, 2013)

Not sure how I would approach such a small detailed part, but one method I haven't investigated is making a mold using Plaster-of-Paris and then vacuum bagging. And I'd be interested if anyone else has?

Best place to start your learning is at Fibreglast. Lots of learning videos.
Learning Center

You can take what you learn there and use your own techniques.


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## JACKofSPADES (Jan 12, 2014)

Testmule said:


> Not sure how I would approach such a small detailed part, but one method I haven't investigated is making a mold using Plaster-of-Paris and then vacuum bagging. And I'd be interested if anyone else has?
> 
> Best place to start your learning is at Fibreglast. Lots of learning videos.
> Learning Center
> ...


Thanx so much


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## mykle (Dec 25, 2013)

The last part is probably made by using pre-preg ( pre inpregnated) weave, which is cut in shape and put onto a mould. The mould is then covered by a vacuum bag and put into an oven ( approx 180 deg maybe) . This part is fairly easy to make. Youtube vacuum infusion moulding. If the first part is relatively short fibres ( ish 2cm) in a random order, they could be pressed into a mould and apply pressurised epoxy. This is called resin transfer moulding, and makes an even less void content and higher fibre fraction than vac inf. The process is faster but the equipment is more expensive. 

If you want to start with composites, go for parts you can make by sheets of weave. Dont use random cloths. Practice with cheap materials like fibre glass and polyester. Check out DIY vacuum pumps or find a cheap one. Look at youtube. Tons of stuff about vac inf there. Many tricks and you will learn a lot by practice.


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## JACKofSPADES (Jan 12, 2014)

mykle said:


> The last part is probably made by using pre-preg ( pre inpregnated) weave, which is cut in shape and put onto a mould. The mould is then covered by a vacuum bag and put into an oven ( approx 180 deg maybe) . This part is fairly easy to make. Youtube vacuum infusion moulding. If the first part is relatively short fibres ( ish 2cm) in a random order, they could be pressed into a mould and apply pressurised epoxy. This is called resin transfer moulding, and makes an even less void content and higher fibre fraction than vac inf. The process is faster but the equipment is more expensive.
> 
> If you want to start with composites, go for parts you can make by sheets of weave. Dont use random cloths. Practice with cheap materials like fibre glass and polyester. Check out DIY vacuum pumps or find a cheap one. Look at youtube. Tons of stuff about vac inf there. Many tricks and you will learn a lot by practice.


Thanx for the help :thumbsup:


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