A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Marty Lyons
Date: 2014 Oct 6, 08:33 -0700
I have previously been using a plastic plate with motor oil. Lots of spills. So I set out, with input from the forum, to make an artificial horizon. I tried a WalMart wall mirror, but way too much distortion in the glass. Ended up with a pack of 5 of 12" x 12" mirror tiles from Lowes, $9.99. Needed one cut to 10" x 12" but could not convince them to cut it. They said the mirror glass tiles would ruin their cutter, yet they cut mirror glass if you buy it at the glass cutting aisle, go figure. So I cut it myself, shattered one piece, but so what. Mounted it to a piece of 3/4" plywood, have the mirror "floating" on a 1/16" foam rubber. Mirror clips are not tightened down for fear of distortion, just hold it laterally on the board. Board is drilled and tapped for three 10-32 stainless screws, fine thread for fine adjustment, ends of screws rounded. Two spirit level vials are epoxied to the board, not for serious leveling, just rough, and for the cool-look factor. Leveling right now is done with a machinist square level which seem pretty good. Working on getting a high precision machinist level.
Quick shots this morning on a concrete patio, yielded the following results, which for me seemed acceptable:
Homemade horizon, 0.7 nM Away, 1.8 nM Toward
Pan of dirty motor oil, 1.4 nM Toward, 2.5 nM Toward
Sextant was an Ogawa Seiki, more trials this afternoon.