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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Fine adjust a Davis Mk 3
From: Don Seltzer
Date: 2016 Mar 26, 09:21 -0400
From: Don Seltzer
Date: 2016 Mar 26, 09:21 -0400
On Sat, Mar 26, 2016 at 2:03 AM, Frank Reed <NoReply_FrankReed@fer3.com> wrote:
The Davis Mk. 3 sextant has one basic functional problem. The index arm works with a pure vernier scale, and it depends on friction between the arm and the arc. There is no adjustment for this. The user slides the arm along as best as possible until the angle is right. It catches and "bounces" with static friction along the arc. Does anyone have any advice on how to "nudge" the arm to get it right?
Just thinking out loud, I wonder if attaching a small vibration device such as a buzzer to the sextant might reduce the stiction. Press a button to turn it on while adjusting the arc, release to 'lock' in place. Of course the major drawback could be if the vibration was enough to shake the sextant and affect the visual sighting.
Don Seltzer
