My six planet orrery was inspired by Hielke Rispens' laser cutable design, which was in turn inspired by MatthewS3's design. Rather than target a laser cutter or shopbot, I modeled the entire orrery in OpenSCAD with a goal of 3D printing the model. I tried to reduce the complexity of the outer planet reduction gear, but messed up the ratios for my first printing.
The gear ratios from the input drive on the second version are better, although Saturn is very slow:
| Planet | Gear ratios | Years | Days | Actual | Error |
|---|---|---|---|---|---|
| Mercury | 74:18 | 0.2432 years | 88.78 days | 87.97 days | 0.9% slow |
| Venus | 57:35 | 0.6140 years | 224.11 days | 224.70 days | 0.27% fast |
| Earth | 46:46 | 1.0000 years | 364.24 days | 364.24 days | exact |
| Mars | 32:60 | 1.8750 years | 684.38 days | 686.98 days | 0.38% fast |
| Jupiter | 16:32, 16:56, 36:61 | 11.8764 years | 4334.88 days | 4322.82 days | 0.27% slow |
| Saturn | 16:32, 16:56, 15:76 | 35.5871 years | 12989.29 days | 10,755.70 days | 20.76% slow |
Still todo is to add a month read-out to the moon ring and a year read-out to the Jupiter ring. It would also be nice to pose the configuration at a known date for printing so that the readouts accurately reflect the position in the orbits.
The orrery not printable on an FDM printer, so I'm trying it at Shapeways with the "Print it now!" option since their automated tests think there might be loose shells (pieces that have a risk of fusing together) as well as thin walls. This is my first involute gear designs, so I'm not sure how well it will turn out.