To: Goran Hosinsky 
From: Stan Truitt 
Cc: atm{at}shore.net
Reply-To: Stan Truitt 


Aloha Goran,

I selected a Futaba proportional MicroServo with a plus & minus 140
degree rotary range.  Being right handed, the focusing knob that would be
used by a left hander was removed from it's shaft and replaced with a
plastic bellcrank.

The bellcrank is mounted to the focusing shaft so that it can slip;
effectively providing a clutching action when the other knob is turned by
hand.  When an eyepiece is placed into the focuser tube, the servo is
centered, and the eyepiece is focused by hand. Then, operating the R/C
unit, hands-off fine focusing corrections are made.

A metal linkage couples the servo bellcrank to the focuser shaft bellcrank.
 The metal linkage is press fit into the bellcrank holes, on both ends, to
avoid free play and lost motion.  A double pully/o-ring scheme was tried at
first, but was replaced because of hysteresis effects with the o-rings, and
difficulties with clutching the pullys.


A fellow island dweller,

Stan Truitt            20ø 51'  N,  156ø 22'  W                 511 Meters MSL

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