Jan 162011
 

Yesterday, the observatory took it’s first step toward automation.   The dome rotation and shutter motors were configured and tested.  Ultimately, both systems will be capable of remote computer control, but for now, being able to open and close the shutter without climbing the 10′ ladder is a major advance.

The rotation tests proceeded without problem.  I wasn’t expecting any as great care was taken in leveling and ‘circularizing’ the base ring.  Unfortunately, less care was taken in the assembly of the base ring as I was completely successful in reversing the left and right segments.  Luckily, the only repercussion is a gap in the pre-configured wiring clamps.

I was more concerned about the shutter.  The shutter mechanism consists of two springs, several tens of feet of flexible wire cable and 29 pulleys.  This is all driven by an electricallly powered gear reduction transmission that turns a 15″ screw that simultaneously retracts and feeds out the flexible cable.  What is curious is the far ends of the open and close cables are fixed to the inside of the dome.  In effect, the cables never move.  Yet the shutter opens and closes.  And it all worked the first time.   I will need to tweak some of the pulley mounts to optimize contact angles, but there were no loud twangs or screeches and the shutter moves smoothly throughout its range of motion.

The next step is to integrate the end-of-motion sensors so the shutter will stop on its own accord.

 Posted by at 08:58

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