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    Re: DIY Davis prism directly on the mirror?
    From: Tony Oz
    Date: 2018 Nov 8, 01:07 -0800

    Dear Brad,

    This is a sketch of where I'd like to glue a prism. Its' edge where the two faces meet should be made parallel to the transparent|mirrored boundary.

    Most sextants I saw so far let the horizontal mirror to rotate slightly in the holder, at least my SNO-T does. So I will definitely need to adjust the mirror+prism position (within ~half degree) using the cross tool - just as the original Davis prism attachment was supposed to be properly aligned. And later on - to re-check the alignment with the same cross tool.

    Actually my question was if there is a reason to NOT have a prism permanently attached (glued) on the horizon mirror. You ask why? - I think it is a convenience and more robust/compact design.

    And I want this prism there exactly for its' indended purpose - to help to align my sextant vertically at sea.

    Please comment.

    Warm regards,


    60°N 30°E

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