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A question about carbon fiber

Discussion in 'CNC Lathes' started by Steven Bloom, Feb 23, 2017.

  1. Steven Bloom

    Steven Bloom Journeyman
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    Hi All, So I built my CNC machine last year and it works okay, Why I say that is that it gets bogged down a bit due to all of the weight I added. This mainly happed becase I used 4.5mm stainless steel plates for everything. And that adds like 40lbs to the machine.

    So this is my question. I have found someone to make me the same parts that I made in stainless before but this time in 4.5mm 3K carbon fiber. The replacement of the parts would e a simple swap in and out. The motors would run a lot better.

    But my question is would the 4.5mm carbon fiber be stiff enough for this kind of applicatiion. Has anyone else done something like this and had positive results ??

    Thansk Steven
     
  2. Anthony Bolgar

    Anthony Bolgar Journeyman
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    I would have the parts remade using aluminum. I do not think that the carbon fiber sheets could take the long term stress that they would be put under. Maybe someone else could give you a more definitive answer, mine is just a gut feeling.
     
  3. Steven Bloom

    Steven Bloom Journeyman
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    Well they have been working great so far. 4.5mm CF is really, really strong !!!
     
  4. MaryD

    MaryD OpenBuilds Team

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    @alex_b has a lot of experience with carbon fiber...maybe he will chime in.
     
  5. alex_b

    alex_b Journeyman
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    Yes, I can attest to the strength of CF plate! I've made a few things from 5mm plate in our shop and it is almost un-bendable in any configuration and extremely light. As for failure modes, keep in mind that CF is a composite material and thus highly ansiotropic and is prone to catastrophic failure if overstressed. Basically meaning it doesn't fail on a gradient, it will go from 100% strength to nothing very quickly unlike metal which will typically warp an bend before breaking. (this is why CF is typically layered with multiple types of aluminum and titanium in aircraft to enhance its strengths and minimize its weaknesses.)

    My 2c on CF. :)
     
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  6. Anthony Bolgar

    Anthony Bolgar Journeyman
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    Thanks for the clarification, I did not know that the strength was not on a gradient.
     
  7. alex_b

    alex_b Journeyman
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    Here's a good video showing it, once it starts to splinter it's basically finished. last test they show kinda speaks for itself. CF is incredibly strong...up until it's not.... lol

     
  8. Gary Caruso

    Gary Caruso OpenBuilds Volunteer
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    Steven, I would love to see more pics of your sea ox, all decked out in CF!
     
  9. Joe Santarsiero

    Joe Santarsiero OB addict
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    It's light, strong, and "brittle". Goes just about straight to catastrophic like you said.
    There's a nice CF F1 drive shaft torsion test on YT.
     
    alex_b likes this.

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