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We were provided with a much larger and more powerful brushed DC motor, but had avoided using it up to this point due to its size and weight. In order to minimize both of these parameters, we removed the drive's encoder, associated electronics, and all-metal gearbox. We then printed a set of reduction gears using spur gears from our gear generator to decrease speed and increase torque at the gearbox output. After several quick iterations, we found a reduction of 36.75:1 (8:24, 8:28, 8:28) produced approximately 15 RPM with more than adequate torque to drive our entire robot. 15 RPM results in one step every ~2 seconds, which is ideal our robot with its sliding counterweight.
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For our final machine, we purchased:
| Part | Source | Quantity |
|---|---|---|
| 3mm steel shaft | generic | ~50mm |
| 5mm steel shaft | generic | ~700mm |
| 5mm precision ground steel shaft | generic | 200mm |
| 3mm x 6mm x 2.5mm ball bearing | generic | 6 pieces |
| 5mm x 9mm x 3mm ball bearing | generic | ~50 pieces |
| M3 x 20mm cap screw | generic | 2 pieces |
| M3 x 30mm cap screw, fully threaded | generic | 1 piece |
| 2in OD cylindrical steel stock | generic | ~1in |
| 5mm x 7mm x 8mm slide bearing | McMaster | 2 pieces |
| 91MXL012 1/8in timing belt | McMaster | 2 pieces |
| 140MXL012 1/8in timing belt | McMaster | 1 piece |
| DC motor | Pololu | 1 piece |
| AA battery pack | Amazon | 1 piece |