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  1. #1
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    Carbon fiber bicycle frame building

    Are you interested in learning how to build a carbon fiber frame? I would like to show you how I built my own carbon fiber frame, from raw material to taking it out for a ride.

  2. #2
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    Hello, my name is Luis Blanc and I build bike frames made out of carbon fiber. I would like to show the process that I follow to design and build such framesets. I'm about to finish a road frame and I will be posting notes on how I'm progressing (including photos). I hope it is informative for you and I hope I can also get help from some of the members of this forum. I would like to mention that I learned how to do all this after attending the carbon fiber frame building course ran by Dave Bohm from Bohemian cycles (Tucson, Arizona)
    Last edited by Duende; 26th June 2016 at 8:19 AM.

  3. #3
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    To begin the construction of a carbon frame, I'll show you how I make the main tubes (down, top and seat tubes). I use a mandrel which is just a solid aluminum cylinder, the diameter required on each tube and wrapped with strips of unidirectional carbon fiber. I use unidirectional carbon so that I can control the direction of maximum tensile strength and compression (that is the direction in which the filaments of the carbon fiber have been arranged). This results in different layers wound on the mandrel with directions ranging from 0 , + 45 , -45 to 90 . In this way I make sure that the tube will respond well to forces in tension, compression and torsion (with the fibers at 45 ). In the picture below, you can see how the strip 45 is wound onto the mandrel.
    tube wrapping.jpg
    Attached Images Attached Images
    Last edited by Duende; 26th June 2016 at 7:55 AM.

  4. #4
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    This is the final result after wrapping all layers,
    IMG_0081.jpg

  5. #5
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    The tube is then introduced in a vacuum bag and subsequently cured in an oven. By the way, I almost forgot to say that I only use carbon fiber that has been pre-impregnated with epoxy resin (pre-preg) as it facilitates the handling of the material lot.

    IMG_0089.jpg

  6. #6
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    And this is the aspect that offer the three tubes once baked and removed from the vacuum bag. As can be seen, the surface of the tubes has a certain roughness. That is because the envelope cloth used for curing tubes. This is solved relatively easily on the basis of subsequent sanding but I am in favor of sanding as little as possible because invariably when sanding, carbon fibers can break and, in a way, the integrity of the piece is compromised. Now I'm trying molds that will leave an outer surface of the tubes completely smooth. The last step is the removal of the aluminum mandrel inside the tubes. This is done very easily if you have cleaned the mandrel with release agent before the wrapping of the carbon strips. If you forget this step, then I can assure you that you will never be able to take off the mandrel form the carbon tubes.
    tubes after curing.jpg
    Last edited by Duende; 26th June 2016 at 7:59 AM.

  7. #7
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    In my next "chapter", I'll show you how I make chain stays, dropouts and the rear brake bridge, all out of molds. See you soon.

  8. #8
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    Thanks Duende - very interesting!

  9. #9
    Senior Member VLAD (the Friendly Vamp)'s Avatar
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    Yarp - will be interesting to see it finished.
    NOT logging in every and each visit now.
    Going to have to BITE someone soon.
    Amicabili Lamia

  10. #10
    Senior Member Boxhilljunkie's Avatar
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    I always thought carbon frames where made in one peice .
    looks good tho..

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