NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brad Morris
Date: 2014 Jan 23, 14:26 -0500
Correct Örjan. Its a Hirth radial interface. From any one position to any other whole degree is accurate (for mine) to 0.5". The repeatability (for mine) is 1/20". Mine is divided into 360 parts (degrees). Its traceable to NIST (National Institute of Standards and Technology) and is calibrated within the last year. It is a spectacular piece of kit.
Bill, I've gone through your post. Yes, the Ultradex can take the place of the SNO-T and make short work of the motion from angle A to angle B. The motion takes just a few seconds of time (5-10, we want to treat the Ultradex with respect). In doing so, we have the accuracy and repeatability detailed above.
I'll make a sketch of the optical path I'm thinking of. Whilst I do have simultaneous access to a Nikon 6D Autocollimator, I would like to try to replicate the original patent. There is a fundamental reason. Last I checked, to purchase the Autocollimator and the Ultradex would cost > $40K. That puts the solution Örjan specified well out of the reach of many.
Patience, the sketch is coming!
Brad
Uhm, i think you are both talking what I have been taught is Hirth Rings, accurate to better than 2 arcseconds and repeatable to 0.5 arcseconds.
A set of 720 tooth rings (two for each indexing platform) should do well as sextant test platform, add a autocollimator and you are set
should make short work of testing each degree to VERY accurate value, better than the readout of the sextant at any rate.
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