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Post by ggroce on Feb 11, 2017 17:08:34 GMT -7
Am I correct in assuming that with the data available in the github, I can build a dobot from scratch? I can machine the aluminum plate or 3d print some parts. The only caveat I see is sourcing the gearboxed stepper motors, which the Dobot team claims they had custom made? Would some generic gearboxed nema 17's off ebay get me in the ballpark? Anybody know what the gear ratio is on the Dobot gearbox?
Max: thanks for making all the data on the Dobot available in one place.
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Post by Max on Feb 11, 2017 17:27:49 GMT -7
I haven't tried to make one myself, but the parts are mostly in the files and, imho, it shouldn't be too hard to reproduce those parts from the files for a person familiar with machining stuff. I only looked at the files' contents, but I have no experience with machining, so take that with a grain of salt.
As to the gears and motors - they are widely available as gear box+motor and are almost physically identical to the ones they installed on dobot. The only problem you may face trying to find off-the-shelf pack for it would be the shaft diameter and the gear ratio. Shaft diameter isn't a show stopper for you, but gear ratio is somewhat a question. They installed 10:1 gear box (reduction), but if you find, say, 7:1 that wouldn't be a big deal - you just adjust some parameters in SDK and that's it. However, keep in mind that the lower the the ratio - the lower the accuracy and the lower the torque (proportionally). At the same time, the higher the ratio - the more accurate and the slower the arm and there is a limit to the stepping frequency, so if you install gears with too high ratio and try to drive if fast it'll simply fall on the ground as steppers at high stepping frequency have no torque whatsoever. You can find a post on this forum describing exactly that case.
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