Quote:
Originally Posted by Steve_C
Ok,
The barn door is coming along. I am playing around with construction methods and processes to get a feel before I make my final unit.
A question I have is, is the perpendicular alignment of the hinge in relation to the longitudinal axis of the arm critical? In my experimental version and with my limited woodworking skills I can get the hinge to within 1 deg of perpindicular to the longitudinal axis of both arms of a single arm design. I can get the threaded rod arm to the correct distance from the centre of the hinge without a problem, am I making myself clear here? I plan on using arms of about 19mm x 100mm.
My motor will be 12VDC, speed controlled with a PWM controller.
TIA
Steve
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Steve,
The errors I worked out for you in an earlier post apply here.
Quote:
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"A 1mm error in the radius, that is where the radius error results in a 1mm greater radius than the ideal radius will result in a drive rate error of 4 arc sec per minute. This is not significant for short exposures on wide angle lenses. Up to 2 min exposures up to 100mm lenses. Accurate polar alignment will present a bigger problem than this error."
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If it isn't quite perpendicular a 1 deg error shouldn't displace the thread by 1mm so it will be less than the error quoted above
Cheers
Joe