A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Tony Oz
Date: 2017 Feb 12, 13:32 -0800
Just got myself a sextant - the FREIBERGER PRÄZISIONSMECHANIK 37/1407/1001 (engaved under the triangle with the "1" inside it), SN 18232 (all this is on the frame), and the red "stamp" with circled "14 DAMG 1" and "55" on the index arm.
All the filters and mirrors are there, though dusty and fingered, the telescope(s) is/are missing. The drum and the "clutch" work fine, there is no play in the worm gear.
First of all I'd be greatly gratefull for a hint on where to get a service manual and all the advises on how to bring the instrument into the best possible condition (as a DIY, at home).
A couple of observations so far:
- both mirrors are "the silver under the glass" type, the light has to traverse each glass twice before reaching my eye. I guess - because of this there is some movement of the reflected image when I rotate the sextant up/down slightly while keeping its' frame in vertical plane (remember - there is no telescope and I have no clear indication of from where exactly I should look into the instrument). The same reason could explain why near-by objects look smaller through the mirrors compared to the straight view through the transparent part of the index mirror (the reflected path is a bit longer than the straight one). I think it is normal and expected.
- there is an index error of approx. 1.5°.
The instrument came just under the USD12 mark and I'm completely happy to have it! :)
I guess the easiest way to use it (without a telescope) is to hack-on an rubber eyepiece pad and a tube to shield the view path from the side lighting.
Tomorrow I'll try to clean the filters with the special liquid for computer monitor screens. I'll leave the mirrors as they are for now.