NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brad Morris
Date: 2013 May 6, 20:27 -0400
Hi Randall
In further thinking about the 180 degree end for end flip, it occurs to me that you need a horizontal reference or you must create one as you go.
CREATE AS YOU GO
Let me assume that the reference surface is not horizontal. Eventually, as I sand the feet, the bubble will always end up on the high side. No amount of end for end flips will move the bubble from there.
At this point, I use the level I'm working on to bring the mirror closer to horizontal, until the bubble starts to show variation in sides as the end to end flip occurs.
Now that the bubble says there's variation of the high side, I sand the feet until I end up with the bubble high to one side independent of flips.
Back and forth, and so on, until both the mirror is level AND there is no variation in bubble with end to end flips.
KNOWN REFERENCE
Of course, I can skip all of this if I have access to a surface plate and can bring it to horizontal, using a machinist's level, to the desired 10 seconds. Then I can just focus on sanding the feet and flipping the level end for end.
May I inquire as to which method you used? It seems to me that the known reference method would be much more straight forward, yet I would think that the create as you go method to be more satisfying. If you used some other method, would you describe your experience?
How long did it take you? Some may think their time or labor is free.
A commercial Freibeger AH, with built in levels, is ~ 600 euros. Of course you spent some on materials. May I ask how much?
I'm just trying to get a sense of how much time and effort you put into making the AH, such that I can compare to the commercial unit.
I assume that you are getting your mirror horizontal to 10". That's something to be rightly proud of. I'd like to hear more of your journey and experience.
Brad
Data from "11 leisurely sights":
5 May 2013
DR 35*19.4 N, 119* 05.5 W
Teperature 75 degrees, roughly.
IC checked 4 May at (-) 0.1
DST ZD +7
All Hs must be divided by 2 for AH use
Body: sun10-14-42
Hs 99* 37.2 a=0.510-18-07
Hs 100* 57.6 a=0.110-22-04
Hs 102* 29.0 a=0.110-26-00
Hs 104* 00.4 a=0.410-29-58
Hs 105* 30.0 a=0.210-34-48
Hs 107* 20.8 a=0.310-37-54
Hs 108* 28.4 a=0.810-42-18
Hs 110* 09.6 a=0.510-46-57
Hs 111* 51.8 a=0.110-50-53
Hs 113* 19.2 a=0.610-54-49
Hs 114* 43.0 a=0.2All reductions were done from USNO site with their sun refraction from + 15.1 to +15.3
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