Alvaro VillosladaOne of the things that I still had to do was to calculate the total cost of Dextra. As I say in the project description, Dextra is a low-cost robotic prosthesis, but how low?
| Component | Pcs | Unit price | Subtotal |
| Pololu Micro Metal
Gearmotor 1000:1 HP with extended motor shaft | 5 | $23,95 | $119,75 |
| DRV8838 Single Brushed DC Motor Driver Carrier | 5 | $2,99 | $14,95 |
| Pololu magnetic encoder for Micro Metal Germotors | 3x packs of two pcs | $8,95 | $26,85 |
| Turnigy TGY-EX5252MG Twin BB Digital Micro Servo | 1 | $9,73 | $9,73 |
| Teensy 3.1 | 1 | $19,80 | $19,80 |
| PLA or ABS filament spool | 750 g | $21,60 | $21,60 |
| Fishing line spool (0.6 mm diameter) | 1 | $8,90 | $8,90 |
| 1/8'' orthodontic elastic rubber bands | Bag of 100 | $5,49 | $5,49 |
| M3x14 bolt | Bag of 50 | $6,25 | $6,25 |
| M3x12 bolt | Bag of 50 | $7,53 | $7,53 |
| M3x8 bolt | Bag of 50 | $6,92 | $6,92 |
| M3x6 bolt | Bag of 50 | $5,42 | $5,42 |
| M3x12 spacer | 2 | $0,471 | $0,942 |
| M3 nut | Bag of 100 | $5,26 | $5,26 |
| Total cost | $259,392 |
So the total cost of building a Dextra hand is $260. Of course, the "per unit" cost is less than this price, because for some components you have to buy more than what is needed to assemble the hand. For example, the total amount of plastic to print the mechanical components of the hand is 142 g (with 20% infill in all the pieces), so the unit cost of the plastic would be a little more than $4. The same happens with the screws, that come in bags of 50 units. When calculating the cost for the unit prices of each component and for the necessary quantities of each one, the price of building a Dextra hand drops to $197.3342. Pretty affordable I think!
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