Grinder Gears

Grinder Gears is a minimalistic gear transmission design. It has two outer gears, a green one with 27 teeth, and a red one with 26 teeth. Those two gears interact with the inner yellow gear. The yellow gear has 26 teeth inside the green gear and 25 teeth inside the red gear. The axis of the yellow hear is 1 mm offset to the axes of the green and red gears. When the yellow gear is turned, its center makes small 1-mm radius rotations, one rotation per tooth skip. This "tooth-skipping" type of action makes the red and green gears rotate with respect to each other because of their different teeth number. For each full rotation of the yellow gear, the red gear has moved one tooth step with respect to the green gear. This way a high reduction ratio is achieved.

The practical application of this gear transmission design is yet unknown. Benefits are its minimalistic near-coaxial design and its compactness. However, it also has a lot of friction and vibration, which may make it unsuited for a powertrain.

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Please order a 3D-printed do-it-yourself puzzle kit from Shapeways at this page (check with Oskar about screws and stickers), or contact Oskar directly if you are interested in obtaining a fully colored, stickered and assembled sample of this puzzling object.