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    Re: Construction of Sextant Arm Pivot Questions ?
    From: Greg Rudzinski
    Date: 2007 Nov 08, 15:21 -0800

    The index arm on my 1970 M.Low U.S. Navy Mark 3 has a single pin with
    two separate cone tapers of the same brass material as the frame
    bearing. Normal wear should seat the tapered pin further into the
    frame keeping the system snug. A pin retainer screw holds everything
    together and sets bearing tightness.
    Greg Rudzinski
    On Nov 8, 5:06 am, Robert11  wrote:
    > Hello,
    > I guess I should introduce myself, somewhat.
    > Am a retired research engineer, and have always been interested in
    > navigation, but, unfortunately, more on the theoretical than the
    > actual "doing" side.
    > However, I did complete the two celestial navigation courses given
    > many, many, years ago by the U.S. Power Squadron, which included the
    > taking of many sextant sites.  Can't remember when i enjoyed any
    > courses more.
    > I don't really have the opportunity to inspect any sextants now
    > firsthand, but am quite interested in how these folks did, and
    > presently are, designing and fabrication the pivots for the arms.
    > Are they just a bored, and subsequently honed, hole for a steel pin ?
    > Is it a cylindrical hole, or tapered ?
    > Is there any "preload" to minimize wobble or looseness with wear ?
    > Different mfg's doing it differently ? In the past ?
    > Any good detailed pix available ?
    > etc.
    > Great Group; have learned much.
    > Regards,
    > Bob   (Sudbury, Mass., USA)
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