A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Noell Wilson
Date: 2021 Sep 9, 07:50 -0700
I ended up with an old Brandis vernier sextant that has some square head adjustment screws but no tool. Drilling and filing is possible but more difficult on deep and/or blind holes. I found a painless substitute in some #8 square drive screws with a 0.112" hole for a 0.110" adjustment screw head. I ran a 1/2" long screw into a small piece of copper tubing with everything slathered with polyurethane glue. Hand grinding the sides of the screw head makes it a reasonable size.
Square drive screw dimensions range from 0.0696" to 0.1910" as shown on https://www.aspenfasteners.com/content/pdf/square_drive_specification.pdf