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    Re: Cylindrical Slide Rule tube poll
    From: Richard M Pisko
    Date: 2010 Jan 19, 22:38 -0700

    On Mon, 18 Jan 2010 12:03:21 -0700, Wolfgang Hasper
    > A kit of all three sizes 300 long each would be nice.
    > Narrow tolerances are required for the outer diameters
    > to fit the scales, the inner diameter is less
    > important. If there is a felt lining as on the
    > original you can easily compensate for 0.2 mm.
    > Aluminium as the material seems preferable but not
    > compulsory. I would not like to have stainless steel,
    > it is heavy and a pain to machine.
    I think a felt liner would be almost essential for prolonged use.
    Aluminum tends to blacken surfaces through rubbing.  A coating of the
    paper or plastic would help, and I had even thought of spraying the inside
    of the outer tube with a thin film of drawing fixative; but I believe that
    felt would be the best solution.
    As for the parallax worry, a metallic pointer can be bent closer to the
    scales if deemed necessary.  The eye can keep the cursor centered in line
    with the axis quite well without aid; but a small bit of silver colored
    mylar at the base of the cursor will reflect the eye pupil well enough to
    allow very repeatable observation positioning.
    Just my opinion.
    Richard . . .
    Using Opera 10

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