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Wire through a hole - diameter question

  1. Aug 26, 2012 #1
    I'm trying to find a silver chain that can be used for a small bead with a small hole. Obviously, the chain needs to be thin enough to fit through the hole, but I can't measure the hole inside the bead by hand.

    I found a chain that is 0.9mm in diameter, but I'm not sure the bead will fit. So I went home and threaded the bead with a 0.3mm wire that I have. It fit through 5 times. So basically, I have a bead strung up on 5 0.3mm wires. With this information, how can I figure out the diameter of the hole, or at least if it is greater than 0.9mm?

    TIA
     
  2. jcsd
  3. Aug 26, 2012 #2
    http://mathworld.wolfram.com/CirclePacking.html

    From the case of five circles packed into one larger circle on this page, you can see that with optimal packing, the diameter of the larger circle is about 2.7 times that of the smaller circles. This means that in your case, if 0.3mm is the diameter of your thinner wire, the chain with 0.9mm diameter may not fit.
     
  4. Aug 26, 2012 #3

    haruspex

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    Turning it around the other way, if a 0.9mm diameter wire would fit then that means three 0.3mm wires would fit with their centres in a straight line; so you should manage 7 wires - a central one and six more arranged around it.
    Of course, practical considerations might mean that 0.9mm would just fit, yet it's quite hard to thread 7 x 0.3mm.
     
  5. Aug 28, 2012 #4
    Go buy a welding tip cleaner at the hardware store. They are very cheap, and have many wires on different sizes in very small increments. Makes a very cheap alternative to a pin or wire gauge set.
     
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