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MkI The first completed prototype. In order to minimize friction we made the bearing using a triangluar card point sitting in a square pyramid cup. This solution had worked on a previous model with the rotor balancing on a single point - in this model we tried to make the rotor captive and, sad to say, it didn't work - it was to difficult to get the accuracy required. In the final event the point moved round the side walls of the cup creating both friction and wobble. |
 point and cup bearing |
| Mk II So - a simpler bearing. In the mark 2 the bearing is simply an oversize hole in the rotor and a 5mm shaft on the main body. The rotor is held in place with loose fitting washers. Surprisingly, this worked very well with only a slight tendency to wobble at high speeds. The rotor is on one side of the model, the bellows on the other, meaning the models can't be put down when in use so... |
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Mk III The latest version. Bellows and rotor on the same side of a 20x10mm section box tube Simplified rotor vanes and finally a simple animation printed on the vanes. Great! What now? Perhaps the subject of a future kit? The instructions for making the bellows should be fun to write! - Rob |
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