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    Re: Sextant Shade (filter) Modification Help
    From: Bill Morris
    Date: 2012 Sep 21, 14:00 -0700


    The glass is "swaged" into place. This means that a thin lip of metal has been bent over the bevelled edge of the glass on one side. It is sometimes possible to lift the lip and free the glass by using a sharp point like the tip of a box cutter blade to raise the metal and then running round with the tip of a scriber. This also gives you a fighting chance of having some metal to bend back over the replacement, or you could use super-glue. Or, if the glass really is useless, you have nothing to lose by breaking it and picking out the pieces. It is then much easier to raise the swaged lip. I assume you have tried a variety of solvents to clean the glass and it is sometimes worth trying a very fine polish like rouge moistened with alcohol or even a good quality metal polish.

    All this is much easier to do if you remove the shade from its mounting. You remove the shades bracket from the sextant (one screw) and look carefully at its structure. Usually, there is an adjusting screw one end. Remove this first. At the other end will be the head of the pin around which the shades rotate. The pin is prevented from rotating by a taper-pin through the bracket. Remove this by tapping on the _narrow_ end. Then tap out the pin by putting a short length of 1.5 to 2 mm rod, such as a piece of bicyle spoke into the screw hole and tapping it. If tempted to replace the screw a little and tap it, resist the temptation; it is easily bent. Sometime the pin is prevented from rotating by a grub screw and, Sodd's Law being what it is, it is nearly always rusted in place. Sometimes there is a screw driver slot each end of the pin, just to make life difficult. Look carefully for a grub screw at one end. This is the end that will not turn...

    If stuck, feel free to contact me off list.

    Bill Morris
    New Zealand
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