Question on airspace in cabinet? (1503)

Discussion in 'Archived Threads 2001-2004' started by Greg P, Jan 22, 2002.

  1. Greg P

    Greg P Stunt Coordinator

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    I believe I read somewhere that I need to calculate the mass of the basket, motor, etc, and subtract it from the internal volume along with bracing.

    1. Some one listed it before, but I cant find it. What is the area for the magnet,motor of the 1503?

    2. How do I calculate the flange on the driver? I saw on the blueprint sight 8.5 in. Is that 8.5 x 8.5 x 1??
     
  2. Brian Bunge

    Brian Bunge Producer

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    Greg,

    1. I believe Pat at Blueprint told me the volume displaced by the motor structure on the 1803 was .24ft^3. Since the 1503 has the same motor structure I believe you could use the same value for it as well.

    2. I'm not sure I understand the question.

    Brian
     
  3. ThomasW

    ThomasW Cinematographer

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  4. Ron Shaw

    Ron Shaw Stunt Coordinator

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    Calculating driver displacement isnt very difficult. As far as magnet assembly goes, just multiply surface area by height. Surface area of a circle is (Pi X R sqared). For the displacement if the cone, use this formula (the small 2's mean squared):[(R1 2 H1)-(R2 2 H2)] Pi/3

    R1 is the radius of the cone (at the surround), R2 is the radius of the cone (at the spider). H1 is the height of the cone from the surround to the spider, H2 is the height of the cone from the surround to the apex (an imaginary point, if the cone continued to taper to a point). Just guess at H2. The figure you get will be close enough. The basket volume itself can usually be ignored, as it will be insignificant. If you are going to the trouble of these calculations, dont forget to add the driver cutout to your box volume if the driver is front mounted.
     

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