01 July 2013

A Lego escapement (and failed slow-motion)

I recently came across a post on the Makezine blog showing a video of a very pleasing mechanism, the MacDowall single-pin escapement. Zach and I recreated it as best we could, although we didn't go as good a job as the original when it came to a rigid support structure. Nevertheless, our copy worked:

[Youtube]

My other aim with this was to experiment with temporal aliasing, to create a slow-motion version of the mechanism. For this to work, I would make a video by taking, say, every 61st frame of the original video. Since the pendulum's period is very unlikely to be an exact multiple of the frame time, I would get a strobe effect and see the mechanism in slow motion. Alas, the fates conspired against me, and my pendulum had a period indistinguishable from (58/29.97)″, as this composite image shows. It's the average of 154 images, each 58 frames apart from the next:

For contrast, here's the average of 154 images, each 57 frames apart from the next (left), and every 59 (right):

By the time I discovered this, I had dismantled the pendulum. Grr.

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