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Since it is now possible to 3D print (using metals) a 1911 semiautomatic
pistol that appears to work rather well.  A traditional sextant could
also be constructed in this manner.  I am amazed that all parts of the
pistol, including screws and springs were printed, wow!  A simple
internet search tells more...

With 3D printing technology, metal components may be fashioned and
optical elements may be molded or perhaps also printed.  Optical
encoders for precision angular metrics are now commonplace.  A large
assortment of fantastic sensors combined with electronic/computing
circuits enjoy wide usage today.  Miniaturization has introduced terms
such as nano and molecular into our vocabulary.  So in my opinion, it
should be possible to build an inexpensive sextant that would have
superior specifications to any sextant today.  Such a device might not
give a mariner more confidence in his position but the resources are
certainly out there.

Why would you want to design, build or own one?  Most agree that no
significant market exists today so the economics of such a venture isn't
very attractive.  Even if 3D printing were used to lower the
manufacturing costs who wants a navigation system known to be somewhat
complex (except for NavList members) and impossible to use when seas are
rough and the weather foul.

If you could afford to modernize this device, why not consider an
alternative that might deliver more while providing a better backup
system for GPS.  Such a system is apparently in use but not available to
the public and it may only work at high altitudes too.  So why not dream
big and consider a multi-body tracking system that would operate during
periods of good seeing whether night or day in a continuous manner.
Even if only night operation is available, inertial guidance could
fill-in when tracking fails during inclement weather or other
disruptions.  It is likely that optical ring gyros are operational on
many platforms today.  Would a system such as this actually give better
positional information than the traditional methods?  I like to think so
but that's another matter.  The goal to create a device that could
compare favorably to the outdated LORAN system while providing global
coverage would be useful if the cost is kept under $...

My dear wife says I need to stop daydreaming and get on with some chores
so you have my meager and not well thought out contribution.
Regardless, no plans here to make a DIY/home-built sextant.

Frank
Rochester, NY

On 1/6/2014 1:22 PM, Frank Reed wrote:
> In another thread, Sean asked:
> "how long before we see the first "3D printable sextant"?"
>
> This question was spawned by some humorous speculation about sextants being 
outlawed which may have brought to mind some recent new stories about 
homemade 3D printed handguns (not really viable at this time). But this is an 
element of a broader question: could you build a reasonably accurate sextant 
at home? Does 3D printing have anything like the required precision at this 
time? Could we re-purpose some other components to create a really good 
angle-measuring instrument?
>
> I'm sure some of you have seen a design, I think originally by Omar Reis, 
that uses a CD case to provide a simple rotating base element. Adding a 
couple of mirrors and a home-printed scale, you get a nice little sextant 
with accuracy around a tenth of a degree if you're careful. Primitive but 
usable. Can that design be improved upon?
>
> Could the pivot of a marine sextant be manufactured by any home "shop" 
techniques, 3D printing or otherwise? How about some digital means of 
producing scales? Would a vernier sextant be easier to produce than a 
micrometer sextant?
>
> And what about a more mechanical sextant (similar to some aviation sextants) 
using a gearbox and showing a "digital" readout for the angle? Could we 
produce something small and very accurate? Fundamentally, a sextant is a very 
simple device: it rotates one mirror with respect to another by a 
pre-determined, readable angle, with high accuracy and repeatability. Surely 
with some elements of modern computer-driven manufacturing, there's a way to 
go beyond the traditional marine sextant design...
>
> -FER
>
>
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