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Carbon Brushes are Graphite right?

  1. Dec 6, 2012 #1
    Carbon Brushes are Graphite ... right???

    I was wondering if the carbon brushes are graphite? and if yes how pure?
    These days I am in Sri Lanka and can't find any seller offering pure graphite tubes, to be used as a heating element.

    So I though what if.... I could use these carbon brushes instead as a cheap & fast alternative until I get one from abroad... lol

    It's not a cleaver thought but any chance it could work???!!!

    Thanks in advance
     
  2. jcsd
  3. Dec 8, 2012 #2

    sophiecentaur

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    Re: Carbon Brushes are Graphite ... right???

    What resistance do you need? By design, brushes are short and fat and have as low a resistance as possible. A heating element needs to have high enough resistance to dissipate the power you require.- hence, long and thin (ish).
     
  4. Dec 8, 2012 #3
    Re: Carbon Brushes are Graphite ... right???

    Brushes are not pure graphite, by a long way - They are a mixture of carbon, graphite and a collection of binders to "glue" them together. They are baked (sintered) during manufacture. When they are running inside a motor, some of those other chemicals are liberated and act as a lubricant between the brush and the commutator....... one of those lubricants, I believe, is plain old water.
     
  5. Dec 8, 2012 #4

    sophiecentaur

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  6. Dec 10, 2012 #5
    Re: Carbon Brushes are Graphite ... right???

    I wonder if a thick pencil core would work?
     
  7. Dec 11, 2012 #6

    sophiecentaur

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    Re: Carbon Brushes are Graphite ... right???

    Yes, in principle - I have done it. You need to specify how much power you want and what your operating voltage will be before you can expect a quantitative answer but you can definitely get a pencil lead too hot to touch!
     
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