Jul 7, 2015
“The Mechanics of the Film Projector” by Steve Kranz and Bill Hammack for Engineer Guy
To me, the most beautiful aspect of the film projector is how all of the mechanisms are synced. The mechanisms are driven by a single rotating axle. The axle rotates the shutter and simultaneously turns the cam that advances the film. Behind the shuttle is a worm screw that drives two gears that are coaxial with the top and bottom sprockets. So this means that with every rotation of the axle, the shutter blocks and flashes light three times, the shuttle pulls down a single frame, and the worm screw rotates the gears and sprockets one fourteenth of revolution.
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