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A test run of part of the planetary-gear clock I'm designing.

In the upper left is a thumb wheel (it sticks out the edge of the wooden frame) that engages the big 10" scalloped gear in the back. The sole purpose of the big scalloped gear is to turn the small (1" diameter) sun gear in the center (hidden under the center of the wood frame. You can see the teeth sticking out), which engages the 5" planet gears, which engage the 11" ring gear at the edge. Everytime the 10" gear goes around once, the planet gears move 1/12 of a circle. This is the basic mechanism for linking minutes to hours.

I will have a two-gear set, one like this, and one with a different set of sun-and-planet gears, to link seconds to minutes. 12:1 is the largest reduction possible with planetary gears, so I'm doing a 12:1 and a 5:1 to get 60:1.

I suppose I could do 6:10, but if I want to use the same ring gear, I'd need some multiple of 495 teeth, which is considerably finer than the current 176.

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Are you going to skeletonize the gears?

I'm not that good of an artist. Instead of skeletons, I was thinking of something like Poincare Disk tessellations, or crossed spirals (like you find in flowers. Heck, even simple spokes would be OK.

Or, in other words, yes, especially for versions of this clock made of opaque materials, I'll skeletonize the gears so you can see all the workings of the clock. Even if I do it in, say, colored transparent acrylic sheet (which is a plan), I'd probably still skeletonize so there's interesting color contrast/overlap.

One set of prototype gears I've made, but not yet photographed, uses a Poincare-disk based seletonization.

Although one clear-acrylic idea I've toyed with is simply cutting plain gears, adding contrasting dots of colored acrylic for the ends of the "hands", and then filling the clock with a mineral oil of the same refractive index as the acrylic. The end result is that the edges of the gears optically disappear, and it looks like a solid block of acrylic with the hand markers floating in it.

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