[ATM] Focuser speed reducer

[Don Clement]

I don't use or need speed reducers. Just use a single fine pitch leadscrew
with zero backlash nuts.  The advantage is no backlash or play from an added
gear (or similar type) reduction mechanism. There is also excellent
repeatability and ultra-smooth movement because the leadscrew nuts average
over many threads and have a very large contact area. Of course fine focus
is inherent with leadscrew focusing whereas the Crayford design has  the
inherent coarse focusing limitation in which a focus reduction mechanism
must be added for any type of fine focus. Also the contact area of the
Crayford is very small, a point or line contact at best so there is also a
limitation on maximum load before slipping occurs.



Don Clement

Running Springs, California





> I've seen lots of great focuser plans out there, but I've never seen
> plans or even a commercial source for a speed reducer like the ones used
> on feathertouch and moonlite focusers to get dual speed focusing.
> Anybody have plans or a source for such a beast?
>
> Thanks, and clear skies!
> -- 
> Michael Lindner
> http://www.starastronomy.org *** http://home.att.net/~mikel
> http://www.atmsite.org *** http://www.atmlist.net
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